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 // _filler_array_max_size is set to humongous object threshold
2223 // but temporarily change it to use CollectedHeap::fill_with_object().
2224 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2225
2226 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2227 // Let's use the existing mechanism for the allocation
2228 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2229 AllocationContext::system());
2230 if (dummy_obj != NULL) {
2231 MemRegion mr(dummy_obj, word_size);
2232 CollectedHeap::fill_with_object(mr);
2233 } else {
2234 // If we can't allocate once, we probably cannot allocate
2235 // again. Let's get out of the loop.
2236 break;
2237 }
2238 }
2239 }
2240 #endif // !PRODUCT
2241
2242 void G1CollectedHeap::increment_old_marking_cycles_started() {
2243 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2244 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2245 "Wrong marking cycle count (started: %d, completed: %d)",
2246 _old_marking_cycles_started, _old_marking_cycles_completed);
2247
2248 _old_marking_cycles_started++;
2249 }
2250
2251 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2252 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2253
2254 // We assume that if concurrent == true, then the caller is a
2255 // concurrent thread that was joined the Suspendible Thread
2256 // Set. If there's ever a cheap way to check this, we should add an
2257 // assert here.
2258
2259 // Given that this method is called at the end of a Full GC or of a
2260 // concurrent cycle, and those can be nested (i.e., a Full GC can
2261 // interrupt a concurrent cycle), the number of full collections
2262 // completed should be either one (in the case where there was no
2263 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2264 // behind the number of full collections started.
2265
2266 // This is the case for the inner caller, i.e. a Full GC.
2267 assert(concurrent ||
2268 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2269 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2270 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2271 "is inconsistent with _old_marking_cycles_completed = %u",
2272 _old_marking_cycles_started, _old_marking_cycles_completed);
2273
2274 // This is the case for the outer caller, i.e. the concurrent cycle.
2275 assert(!concurrent ||
2276 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2277 "for outer caller (concurrent cycle): "
2278 "_old_marking_cycles_started = %u "
2279 "is inconsistent with _old_marking_cycles_completed = %u",
2280 _old_marking_cycles_started, _old_marking_cycles_completed);
2281
2282 _old_marking_cycles_completed += 1;
2283
2284 // We need to clear the "in_progress" flag in the CM thread before
2285 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2286 // is set) so that if a waiter requests another System.gc() it doesn't
2287 // incorrectly see that a marking cycle is still in progress.
2288 if (concurrent) {
2289 _cmThread->set_idle();
2290 }
2291
2292 // This notify_all() will ensure that a thread that called
2293 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2294 // and it's waiting for a full GC to finish will be woken up. It is
2295 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2296 FullGCCount_lock->notify_all();
2297 }
2298
2299 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2300 GCIdMarkAndRestore conc_gc_id_mark;
2301 collector_state()->set_concurrent_cycle_started(true);
2302 _gc_timer_cm->register_gc_start(start_time);
2303
2304 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2305 trace_heap_before_gc(_gc_tracer_cm);
2306 _cmThread->set_gc_id(GCId::current());
2307 }
2308
2309 void G1CollectedHeap::register_concurrent_cycle_end() {
2310 if (collector_state()->concurrent_cycle_started()) {
2311 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2312 if (_cm->has_aborted()) {
2313 _gc_tracer_cm->report_concurrent_mode_failure();
2314 }
2315
2316 _gc_timer_cm->register_gc_end();
2317 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2318
2319 // Clear state variables to prepare for the next concurrent cycle.
2320 collector_state()->set_concurrent_cycle_started(false);
2321 _heap_summary_sent = false;
2322 }
2323 }
2324
2325 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2326 if (collector_state()->concurrent_cycle_started()) {
2327 // This function can be called when:
2328 // the cleanup pause is run
2329 // the concurrent cycle is aborted before the cleanup pause.
2330 // the concurrent cycle is aborted after the cleanup pause,
2331 // but before the concurrent cycle end has been registered.
2332 // Make sure that we only send the heap information once.
2333 if (!_heap_summary_sent) {
2334 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2335 trace_heap_after_gc(_gc_tracer_cm);
2336 _heap_summary_sent = true;
2337 }
2338 }
2339 }
2340
2341 void G1CollectedHeap::collect(GCCause::Cause cause) {
2342 assert_heap_not_locked();
2343
2344 uint gc_count_before;
2345 uint old_marking_count_before;
2346 uint full_gc_count_before;
2347 bool retry_gc;
2348
2349 do {
2350 retry_gc = false;
2351
2352 {
2353 MutexLocker ml(Heap_lock);
2354
2355 // Read the GC count while holding the Heap_lock
2356 gc_count_before = total_collections();
2357 full_gc_count_before = total_full_collections();
2358 old_marking_count_before = _old_marking_cycles_started;
2359 }
2360
2361 if (should_do_concurrent_full_gc(cause)) {
2362 // Schedule an initial-mark evacuation pause that will start a
2363 // concurrent cycle. We're setting word_size to 0 which means that
2364 // we are not requesting a post-GC allocation.
2365 VM_G1IncCollectionPause op(gc_count_before,
2366 0, /* word_size */
2367 true, /* should_initiate_conc_mark */
2368 g1_policy()->max_pause_time_ms(),
2369 cause);
2370 op.set_allocation_context(AllocationContext::current());
2371
2372 VMThread::execute(&op);
2373 if (!op.pause_succeeded()) {
2374 if (old_marking_count_before == _old_marking_cycles_started) {
2375 retry_gc = op.should_retry_gc();
2376 } else {
2377 // A Full GC happened while we were trying to schedule the
2378 // initial-mark GC. No point in starting a new cycle given
2379 // that the whole heap was collected anyway.
2380 }
2381
2382 if (retry_gc) {
2383 if (GC_locker::is_active_and_needs_gc()) {
2384 GC_locker::stall_until_clear();
2385 }
2386 }
2387 }
2388 } else {
2389 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2390 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2391
2392 // Schedule a standard evacuation pause. We're setting word_size
2393 // to 0 which means that we are not requesting a post-GC allocation.
2394 VM_G1IncCollectionPause op(gc_count_before,
2395 0, /* word_size */
2396 false, /* should_initiate_conc_mark */
2397 g1_policy()->max_pause_time_ms(),
2398 cause);
2399 VMThread::execute(&op);
2400 } else {
2401 // Schedule a Full GC.
2402 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2403 VMThread::execute(&op);
2404 }
2405 }
2406 } while (retry_gc);
2407 }
2408
2409 bool G1CollectedHeap::is_in(const void* p) const {
2410 if (_hrm.reserved().contains(p)) {
2411 // Given that we know that p is in the reserved space,
2412 // heap_region_containing() should successfully
2413 // return the containing region.
2414 HeapRegion* hr = heap_region_containing(p);
2415 return hr->is_in(p);
2416 } else {
2417 return false;
2418 }
2419 }
2420
2421 #ifdef ASSERT
2422 bool G1CollectedHeap::is_in_exact(const void* p) const {
2423 bool contains = reserved_region().contains(p);
2424 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2425 if (contains && available) {
2426 return true;
2427 } else {
2428 return false;
2429 }
2430 }
2431 #endif
2432
2433 bool G1CollectedHeap::obj_in_cs(oop obj) {
2434 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2435 return r != NULL && r->in_collection_set();
2436 }
2437
2438 // Iteration functions.
2439
2440 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2441
2442 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2443 ExtendedOopClosure* _cl;
2444 public:
2445 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2446 bool doHeapRegion(HeapRegion* r) {
2447 if (!r->is_continues_humongous()) {
2448 r->oop_iterate(_cl);
2449 }
2450 return false;
2451 }
2452 };
2453
2454 // Iterates an ObjectClosure over all objects within a HeapRegion.
2455
2456 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2457 ObjectClosure* _cl;
2458 public:
2459 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2460 bool doHeapRegion(HeapRegion* r) {
2461 if (!r->is_continues_humongous()) {
2462 r->object_iterate(_cl);
2463 }
2464 return false;
2465 }
2466 };
2467
2468 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2469 IterateObjectClosureRegionClosure blk(cl);
2470 heap_region_iterate(&blk);
2471 }
2472
2473 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2474 _hrm.iterate(cl);
2475 }
2476
2477 void
2478 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2479 uint worker_id,
2480 HeapRegionClaimer *hrclaimer,
2481 bool concurrent) const {
2482 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2483 }
2484
2485 // Clear the cached CSet starting regions and (more importantly)
2486 // the time stamps. Called when we reset the GC time stamp.
2487 void G1CollectedHeap::clear_cset_start_regions() {
2488 assert(_worker_cset_start_region != NULL, "sanity");
2489 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2490
2491 for (uint i = 0; i < ParallelGCThreads; i++) {
2492 _worker_cset_start_region[i] = NULL;
2493 _worker_cset_start_region_time_stamp[i] = 0;
2494 }
2495 }
2496
2497 // Given the id of a worker, obtain or calculate a suitable
2498 // starting region for iterating over the current collection set.
2499 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2500 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2501
2502 HeapRegion* result = NULL;
2503 unsigned gc_time_stamp = get_gc_time_stamp();
2504
2505 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2506 // Cached starting region for current worker was set
2507 // during the current pause - so it's valid.
2508 // Note: the cached starting heap region may be NULL
2509 // (when the collection set is empty).
2510 result = _worker_cset_start_region[worker_i];
2511 assert(result == NULL || result->in_collection_set(), "sanity");
2512 return result;
2513 }
2514
2515 // The cached entry was not valid so let's calculate
2516 // a suitable starting heap region for this worker.
2517
2518 // We want the parallel threads to start their collection
2519 // set iteration at different collection set regions to
2520 // avoid contention.
2521 // If we have:
2522 // n collection set regions
2523 // p threads
2524 // Then thread t will start at region floor ((t * n) / p)
2525
2526 result = g1_policy()->collection_set();
2527 uint cs_size = g1_policy()->cset_region_length();
2528 uint active_workers = workers()->active_workers();
2529
2530 uint end_ind = (cs_size * worker_i) / active_workers;
2531 uint start_ind = 0;
2532
2533 if (worker_i > 0 &&
2534 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2535 // Previous workers starting region is valid
2536 // so let's iterate from there
2537 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2538 result = _worker_cset_start_region[worker_i - 1];
2539 }
2540
2541 for (uint i = start_ind; i < end_ind; i++) {
2542 result = result->next_in_collection_set();
2543 }
2544
2545 // Note: the calculated starting heap region may be NULL
2546 // (when the collection set is empty).
2547 assert(result == NULL || result->in_collection_set(), "sanity");
2548 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2549 "should be updated only once per pause");
2550 _worker_cset_start_region[worker_i] = result;
2551 OrderAccess::storestore();
2552 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2553 return result;
2554 }
2555
2556 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2557 HeapRegion* r = g1_policy()->collection_set();
2558 while (r != NULL) {
2559 HeapRegion* next = r->next_in_collection_set();
2560 if (cl->doHeapRegion(r)) {
2561 cl->incomplete();
2562 return;
2563 }
2564 r = next;
2565 }
2566 }
2567
2568 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2569 HeapRegionClosure *cl) {
2570 if (r == NULL) {
2571 // The CSet is empty so there's nothing to do.
2572 return;
2573 }
2574
2575 assert(r->in_collection_set(),
2576 "Start region must be a member of the collection set.");
2577 HeapRegion* cur = r;
2578 while (cur != NULL) {
2579 HeapRegion* next = cur->next_in_collection_set();
2580 if (cl->doHeapRegion(cur) && false) {
2581 cl->incomplete();
2582 return;
2583 }
2584 cur = next;
2585 }
2586 cur = g1_policy()->collection_set();
2587 while (cur != r) {
2588 HeapRegion* next = cur->next_in_collection_set();
2589 if (cl->doHeapRegion(cur) && false) {
2590 cl->incomplete();
2591 return;
2592 }
2593 cur = next;
2594 }
2595 }
2596
2597 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2598 HeapRegion* result = _hrm.next_region_in_heap(from);
2599 while (result != NULL && result->is_pinned()) {
2600 result = _hrm.next_region_in_heap(result);
2601 }
2602 return result;
2603 }
2604
2605 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2606 HeapRegion* hr = heap_region_containing(addr);
2607 return hr->block_start(addr);
2608 }
2609
2610 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2611 HeapRegion* hr = heap_region_containing(addr);
2612 return hr->block_size(addr);
2613 }
2614
2615 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2616 HeapRegion* hr = heap_region_containing(addr);
2617 return hr->block_is_obj(addr);
2618 }
2619
2620 bool G1CollectedHeap::supports_tlab_allocation() const {
2621 return true;
2622 }
2623
2624 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2625 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2626 }
2627
2628 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2629 return young_list()->eden_used_bytes();
2630 }
2631
2632 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2633 // must be equal to the humongous object limit.
2634 size_t G1CollectedHeap::max_tlab_size() const {
2635 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2636 }
2637
2638 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2639 AllocationContext_t context = AllocationContext::current();
2640 return _allocator->unsafe_max_tlab_alloc(context);
2641 }
2642
2643 size_t G1CollectedHeap::max_capacity() const {
2644 return _hrm.reserved().byte_size();
2645 }
2646
2647 jlong G1CollectedHeap::millis_since_last_gc() {
2648 // assert(false, "NYI");
2649 return 0;
2650 }
2651
2652 void G1CollectedHeap::prepare_for_verify() {
2653 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2654 ensure_parsability(false);
2655 }
2656 g1_rem_set()->prepare_for_verify();
2657 }
2658
2659 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2660 VerifyOption vo) {
2661 switch (vo) {
2662 case VerifyOption_G1UsePrevMarking:
2663 return hr->obj_allocated_since_prev_marking(obj);
2664 case VerifyOption_G1UseNextMarking:
2665 return hr->obj_allocated_since_next_marking(obj);
2666 case VerifyOption_G1UseMarkWord:
2667 return false;
2668 default:
2669 ShouldNotReachHere();
2670 }
2671 return false; // keep some compilers happy
2672 }
2673
2674 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2675 switch (vo) {
2676 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2677 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2678 case VerifyOption_G1UseMarkWord: return NULL;
2679 default: ShouldNotReachHere();
2680 }
2681 return NULL; // keep some compilers happy
2682 }
2683
2684 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2685 switch (vo) {
2686 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2687 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2688 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2689 default: ShouldNotReachHere();
2690 }
2691 return false; // keep some compilers happy
2692 }
2693
2694 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2695 switch (vo) {
2696 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2697 case VerifyOption_G1UseNextMarking: return "NTAMS";
2698 case VerifyOption_G1UseMarkWord: return "NONE";
2699 default: ShouldNotReachHere();
2700 }
2701 return NULL; // keep some compilers happy
2702 }
2703
2704 class VerifyRootsClosure: public OopClosure {
2705 private:
2706 G1CollectedHeap* _g1h;
2707 VerifyOption _vo;
2708 bool _failures;
2709 public:
2710 // _vo == UsePrevMarking -> use "prev" marking information,
2711 // _vo == UseNextMarking -> use "next" marking information,
2712 // _vo == UseMarkWord -> use mark word from object header.
2713 VerifyRootsClosure(VerifyOption vo) :
2714 _g1h(G1CollectedHeap::heap()),
2715 _vo(vo),
2716 _failures(false) { }
2717
2718 bool failures() { return _failures; }
2719
2720 template <class T> void do_oop_nv(T* p) {
2721 T heap_oop = oopDesc::load_heap_oop(p);
2722 if (!oopDesc::is_null(heap_oop)) {
2723 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2724 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2725 LogHandle(gc, verify) log;
2726 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2727 if (_vo == VerifyOption_G1UseMarkWord) {
2728 log.info(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2729 }
2730 ResourceMark rm;
2731 obj->print_on(log.info_stream());
2732 _failures = true;
2733 }
2734 }
2735 }
2736
2737 void do_oop(oop* p) { do_oop_nv(p); }
2738 void do_oop(narrowOop* p) { do_oop_nv(p); }
2739 };
2740
2741 class G1VerifyCodeRootOopClosure: public OopClosure {
2742 G1CollectedHeap* _g1h;
2743 OopClosure* _root_cl;
2744 nmethod* _nm;
2745 VerifyOption _vo;
2746 bool _failures;
2747
2748 template <class T> void do_oop_work(T* p) {
2749 // First verify that this root is live
2750 _root_cl->do_oop(p);
2751
2752 if (!G1VerifyHeapRegionCodeRoots) {
2753 // We're not verifying the code roots attached to heap region.
2754 return;
2755 }
2756
2757 // Don't check the code roots during marking verification in a full GC
2758 if (_vo == VerifyOption_G1UseMarkWord) {
2759 return;
2760 }
2761
2762 // Now verify that the current nmethod (which contains p) is
2763 // in the code root list of the heap region containing the
2764 // object referenced by p.
2765
2766 T heap_oop = oopDesc::load_heap_oop(p);
2767 if (!oopDesc::is_null(heap_oop)) {
2768 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2769
2770 // Now fetch the region containing the object
2771 HeapRegion* hr = _g1h->heap_region_containing(obj);
2772 HeapRegionRemSet* hrrs = hr->rem_set();
2773 // Verify that the strong code root list for this region
2774 // contains the nmethod
2775 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2776 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2777 "from nmethod " PTR_FORMAT " not in strong "
2778 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2779 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2780 _failures = true;
2781 }
2782 }
2783 }
2784
2785 public:
2786 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2787 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2788
2789 void do_oop(oop* p) { do_oop_work(p); }
2790 void do_oop(narrowOop* p) { do_oop_work(p); }
2791
2792 void set_nmethod(nmethod* nm) { _nm = nm; }
2793 bool failures() { return _failures; }
2794 };
2795
2796 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2797 G1VerifyCodeRootOopClosure* _oop_cl;
2798
2799 public:
2800 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2801 _oop_cl(oop_cl) {}
2802
2803 void do_code_blob(CodeBlob* cb) {
2804 nmethod* nm = cb->as_nmethod_or_null();
2805 if (nm != NULL) {
2806 _oop_cl->set_nmethod(nm);
2807 nm->oops_do(_oop_cl);
2808 }
2809 }
2810 };
2811
2812 class YoungRefCounterClosure : public OopClosure {
2813 G1CollectedHeap* _g1h;
2814 int _count;
2815 public:
2816 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2817 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2818 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2819
2820 int count() { return _count; }
2821 void reset_count() { _count = 0; };
2822 };
2823
2824 class VerifyKlassClosure: public KlassClosure {
2825 YoungRefCounterClosure _young_ref_counter_closure;
2826 OopClosure *_oop_closure;
2827 public:
2828 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2829 void do_klass(Klass* k) {
2830 k->oops_do(_oop_closure);
2831
2832 _young_ref_counter_closure.reset_count();
2833 k->oops_do(&_young_ref_counter_closure);
2834 if (_young_ref_counter_closure.count() > 0) {
2835 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2836 }
2837 }
2838 };
2839
2840 class VerifyLivenessOopClosure: public OopClosure {
2841 G1CollectedHeap* _g1h;
2842 VerifyOption _vo;
2843 public:
2844 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2845 _g1h(g1h), _vo(vo)
2846 { }
2847 void do_oop(narrowOop *p) { do_oop_work(p); }
2848 void do_oop( oop *p) { do_oop_work(p); }
2849
2850 template <class T> void do_oop_work(T *p) {
2851 oop obj = oopDesc::load_decode_heap_oop(p);
2852 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2853 "Dead object referenced by a not dead object");
2854 }
2855 };
2856
2857 class VerifyObjsInRegionClosure: public ObjectClosure {
2858 private:
2859 G1CollectedHeap* _g1h;
2860 size_t _live_bytes;
2861 HeapRegion *_hr;
2862 VerifyOption _vo;
2863 public:
2864 // _vo == UsePrevMarking -> use "prev" marking information,
2865 // _vo == UseNextMarking -> use "next" marking information,
2866 // _vo == UseMarkWord -> use mark word from object header.
2867 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2868 : _live_bytes(0), _hr(hr), _vo(vo) {
2869 _g1h = G1CollectedHeap::heap();
2870 }
2871 void do_object(oop o) {
2872 VerifyLivenessOopClosure isLive(_g1h, _vo);
2873 assert(o != NULL, "Huh?");
2874 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2875 // If the object is alive according to the mark word,
2876 // then verify that the marking information agrees.
2877 // Note we can't verify the contra-positive of the
2878 // above: if the object is dead (according to the mark
2879 // word), it may not be marked, or may have been marked
2880 // but has since became dead, or may have been allocated
2881 // since the last marking.
2882 if (_vo == VerifyOption_G1UseMarkWord) {
2883 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2884 }
2885
2886 o->oop_iterate_no_header(&isLive);
2887 if (!_hr->obj_allocated_since_prev_marking(o)) {
2888 size_t obj_size = o->size(); // Make sure we don't overflow
2889 _live_bytes += (obj_size * HeapWordSize);
2890 }
2891 }
2892 }
2893 size_t live_bytes() { return _live_bytes; }
2894 };
2895
2896 class VerifyArchiveOopClosure: public OopClosure {
2897 public:
2898 VerifyArchiveOopClosure(HeapRegion *hr) { }
2899 void do_oop(narrowOop *p) { do_oop_work(p); }
2900 void do_oop( oop *p) { do_oop_work(p); }
2901
2902 template <class T> void do_oop_work(T *p) {
2903 oop obj = oopDesc::load_decode_heap_oop(p);
2904 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2905 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2906 p2i(p), p2i(obj));
2907 }
2908 };
2909
2910 class VerifyArchiveRegionClosure: public ObjectClosure {
2911 public:
2912 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2913 // Verify that all object pointers are to archive regions.
2914 void do_object(oop o) {
2915 VerifyArchiveOopClosure checkOop(NULL);
2916 assert(o != NULL, "Should not be here for NULL oops");
2917 o->oop_iterate_no_header(&checkOop);
2918 }
2919 };
2920
2921 class VerifyRegionClosure: public HeapRegionClosure {
2922 private:
2923 bool _par;
2924 VerifyOption _vo;
2925 bool _failures;
2926 public:
2927 // _vo == UsePrevMarking -> use "prev" marking information,
2928 // _vo == UseNextMarking -> use "next" marking information,
2929 // _vo == UseMarkWord -> use mark word from object header.
2930 VerifyRegionClosure(bool par, VerifyOption vo)
2931 : _par(par),
2932 _vo(vo),
2933 _failures(false) {}
2934
2935 bool failures() {
2936 return _failures;
2937 }
2938
2939 bool doHeapRegion(HeapRegion* r) {
2940 // For archive regions, verify there are no heap pointers to
2941 // non-pinned regions. For all others, verify liveness info.
2942 if (r->is_archive()) {
2943 VerifyArchiveRegionClosure verify_oop_pointers(r);
2944 r->object_iterate(&verify_oop_pointers);
2945 return true;
2946 }
2947 if (!r->is_continues_humongous()) {
2948 bool failures = false;
2949 r->verify(_vo, &failures);
2950 if (failures) {
2951 _failures = true;
2952 } else if (!r->is_starts_humongous()) {
2953 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2954 r->object_iterate(¬_dead_yet_cl);
2955 if (_vo != VerifyOption_G1UseNextMarking) {
2956 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2957 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2958 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2959 _failures = true;
2960 }
2961 } else {
2962 // When vo == UseNextMarking we cannot currently do a sanity
2963 // check on the live bytes as the calculation has not been
2964 // finalized yet.
2965 }
2966 }
2967 }
2968 return false; // stop the region iteration if we hit a failure
2969 }
2970 };
2971
2972 // This is the task used for parallel verification of the heap regions
2973
2974 class G1ParVerifyTask: public AbstractGangTask {
2975 private:
2976 G1CollectedHeap* _g1h;
2977 VerifyOption _vo;
2978 bool _failures;
2979 HeapRegionClaimer _hrclaimer;
2980
2981 public:
2982 // _vo == UsePrevMarking -> use "prev" marking information,
2983 // _vo == UseNextMarking -> use "next" marking information,
2984 // _vo == UseMarkWord -> use mark word from object header.
2985 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
2986 AbstractGangTask("Parallel verify task"),
2987 _g1h(g1h),
2988 _vo(vo),
2989 _failures(false),
2990 _hrclaimer(g1h->workers()->active_workers()) {}
2991
2992 bool failures() {
2993 return _failures;
2994 }
2995
2996 void work(uint worker_id) {
2997 HandleMark hm;
2998 VerifyRegionClosure blk(true, _vo);
2999 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3000 if (blk.failures()) {
3001 _failures = true;
3002 }
3003 }
3004 };
3005
3006 void G1CollectedHeap::verify(VerifyOption vo) {
3007 if (!SafepointSynchronize::is_at_safepoint()) {
3008 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3009 }
3010
3011 assert(Thread::current()->is_VM_thread(),
3012 "Expected to be executed serially by the VM thread at this point");
3013
3014 log_debug(gc, verify)("Roots");
3015 VerifyRootsClosure rootsCl(vo);
3016 VerifyKlassClosure klassCl(this, &rootsCl);
3017 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3018
3019 // We apply the relevant closures to all the oops in the
3020 // system dictionary, class loader data graph, the string table
3021 // and the nmethods in the code cache.
3022 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3023 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3024
3025 {
3026 G1RootProcessor root_processor(this, 1);
3027 root_processor.process_all_roots(&rootsCl,
3028 &cldCl,
3029 &blobsCl);
3030 }
3031
3032 bool failures = rootsCl.failures() || codeRootsCl.failures();
3033
3034 if (vo != VerifyOption_G1UseMarkWord) {
3035 // If we're verifying during a full GC then the region sets
3036 // will have been torn down at the start of the GC. Therefore
3037 // verifying the region sets will fail. So we only verify
3038 // the region sets when not in a full GC.
3039 log_debug(gc, verify)("HeapRegionSets");
3040 verify_region_sets();
3041 }
3042
3043 log_debug(gc, verify)("HeapRegions");
3044 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3045
3046 G1ParVerifyTask task(this, vo);
3047 workers()->run_task(&task);
3048 if (task.failures()) {
3049 failures = true;
3050 }
3051
3052 } else {
3053 VerifyRegionClosure blk(false, vo);
3054 heap_region_iterate(&blk);
3055 if (blk.failures()) {
3056 failures = true;
3057 }
3058 }
3059
3060 if (G1StringDedup::is_enabled()) {
3061 log_debug(gc, verify)("StrDedup");
3062 G1StringDedup::verify();
3063 }
3064
3065 if (failures) {
3066 log_info(gc, verify)("Heap after failed verification:");
3067 // It helps to have the per-region information in the output to
3068 // help us track down what went wrong. This is why we call
3069 // print_extended_on() instead of print_on().
3070 LogHandle(gc, verify) log;
3071 ResourceMark rm;
3072 print_extended_on(log.info_stream());
3073 }
3074 guarantee(!failures, "there should not have been any failures");
3075 }
3076
3077 double G1CollectedHeap::verify(bool guard, const char* msg) {
3078 double verify_time_ms = 0.0;
3079
3080 if (guard && total_collections() >= VerifyGCStartAt) {
3081 double verify_start = os::elapsedTime();
3082 HandleMark hm; // Discard invalid handles created during verification
3083 prepare_for_verify();
3084 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3085 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3086 }
3087
3088 return verify_time_ms;
3089 }
3090
3091 void G1CollectedHeap::verify_before_gc() {
3092 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3093 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3094 }
3095
3096 void G1CollectedHeap::verify_after_gc() {
3097 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3098 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3099 }
3100
3101 class PrintRegionClosure: public HeapRegionClosure {
3102 outputStream* _st;
3103 public:
3104 PrintRegionClosure(outputStream* st) : _st(st) {}
3105 bool doHeapRegion(HeapRegion* r) {
3106 r->print_on(_st);
3107 return false;
3108 }
3109 };
3110
3111 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3112 const HeapRegion* hr,
3113 const VerifyOption vo) const {
3114 switch (vo) {
3115 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3116 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3117 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3118 default: ShouldNotReachHere();
3119 }
3120 return false; // keep some compilers happy
3121 }
3122
3123 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3124 const VerifyOption vo) const {
3125 switch (vo) {
3126 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3127 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3128 case VerifyOption_G1UseMarkWord: {
3129 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3130 return !obj->is_gc_marked() && !hr->is_archive();
3131 }
3132 default: ShouldNotReachHere();
3133 }
3134 return false; // keep some compilers happy
3135 }
3136
3137 void G1CollectedHeap::print_on(outputStream* st) const {
3138 st->print(" %-20s", "garbage-first heap");
3139 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3140 capacity()/K, used_unlocked()/K);
3141 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3142 p2i(_hrm.reserved().start()),
3143 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3144 p2i(_hrm.reserved().end()));
3145 st->cr();
3146 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3147 uint young_regions = _young_list->length();
3148 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3149 (size_t) young_regions * HeapRegion::GrainBytes / K);
3150 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3151 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3152 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3153 st->cr();
3154 MetaspaceAux::print_on(st);
3155 }
3156
3157 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3158 print_on(st);
3159
3160 // Print the per-region information.
3161 st->cr();
3162 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3163 "HS=humongous(starts), HC=humongous(continues), "
3164 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3165 "PTAMS=previous top-at-mark-start, "
3166 "NTAMS=next top-at-mark-start)");
3167 PrintRegionClosure blk(st);
3168 heap_region_iterate(&blk);
3169 }
3170
3171 void G1CollectedHeap::print_on_error(outputStream* st) const {
3172 this->CollectedHeap::print_on_error(st);
3173
3174 if (_cm != NULL) {
3175 st->cr();
3176 _cm->print_on_error(st);
3177 }
3178 }
3179
3180 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3181 workers()->print_worker_threads_on(st);
3182 _cmThread->print_on(st);
3183 st->cr();
3184 _cm->print_worker_threads_on(st);
3185 _cg1r->print_worker_threads_on(st);
3186 if (G1StringDedup::is_enabled()) {
3187 G1StringDedup::print_worker_threads_on(st);
3188 }
3189 }
3190
3191 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3192 workers()->threads_do(tc);
3193 tc->do_thread(_cmThread);
3194 _cg1r->threads_do(tc);
3195 if (G1StringDedup::is_enabled()) {
3196 G1StringDedup::threads_do(tc);
3197 }
3198 }
3199
3200 void G1CollectedHeap::print_tracing_info() const {
3201 // We'll overload this to mean "trace GC pause statistics."
3202 if (TraceYoungGenTime || TraceOldGenTime) {
3203 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3204 // to that.
3205 g1_policy()->print_tracing_info();
3206 }
3207 g1_rem_set()->print_summary_info();
3208 concurrent_mark()->print_summary_info();
3209 g1_policy()->print_yg_surv_rate_info();
3210 }
3211
3212 #ifndef PRODUCT
3213 // Helpful for debugging RSet issues.
3214
3215 class PrintRSetsClosure : public HeapRegionClosure {
3216 private:
3217 const char* _msg;
3218 size_t _occupied_sum;
3219
3220 public:
3221 bool doHeapRegion(HeapRegion* r) {
3222 HeapRegionRemSet* hrrs = r->rem_set();
3223 size_t occupied = hrrs->occupied();
3224 _occupied_sum += occupied;
3225
3226 tty->print_cr("Printing RSet for region " HR_FORMAT,
3227 HR_FORMAT_PARAMS(r));
3228 if (occupied == 0) {
3229 tty->print_cr(" RSet is empty");
3230 } else {
3231 hrrs->print();
3232 }
3233 tty->print_cr("----------");
3234 return false;
3235 }
3236
3237 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3238 tty->cr();
3239 tty->print_cr("========================================");
3240 tty->print_cr("%s", msg);
3241 tty->cr();
3242 }
3243
3244 ~PrintRSetsClosure() {
3245 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3246 tty->print_cr("========================================");
3247 tty->cr();
3248 }
3249 };
3250
3251 void G1CollectedHeap::print_cset_rsets() {
3252 PrintRSetsClosure cl("Printing CSet RSets");
3253 collection_set_iterate(&cl);
3254 }
3255
3256 void G1CollectedHeap::print_all_rsets() {
3257 PrintRSetsClosure cl("Printing All RSets");;
3258 heap_region_iterate(&cl);
3259 }
3260 #endif // PRODUCT
3261
3262 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3263 YoungList* young_list = heap()->young_list();
3264
3265 size_t eden_used_bytes = young_list->eden_used_bytes();
3266 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3267
3268 size_t eden_capacity_bytes =
3269 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3270
3271 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3272 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3273 }
3274
3275 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3276 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3277 stats->unused(), stats->used(), stats->region_end_waste(),
3278 stats->regions_filled(), stats->direct_allocated(),
3279 stats->failure_used(), stats->failure_waste());
3280 }
3281
3282 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3283 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3284 gc_tracer->report_gc_heap_summary(when, heap_summary);
3285
3286 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3287 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3288 }
3289
3290
3291 G1CollectedHeap* G1CollectedHeap::heap() {
3292 CollectedHeap* heap = Universe::heap();
3293 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3294 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3295 return (G1CollectedHeap*)heap;
3296 }
3297
3298 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3299 // always_do_update_barrier = false;
3300 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3301 // Fill TLAB's and such
3302 accumulate_statistics_all_tlabs();
3303 ensure_parsability(true);
3304
3305 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3306 }
3307
3308 void G1CollectedHeap::gc_epilogue(bool full) {
3309 // we are at the end of the GC. Total collections has already been increased.
3310 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3311
3312 // FIXME: what is this about?
3313 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3314 // is set.
3315 #if defined(COMPILER2) || INCLUDE_JVMCI
3316 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3317 #endif
3318 // always_do_update_barrier = true;
3319
3320 resize_all_tlabs();
3321 allocation_context_stats().update(full);
3322
3323 // We have just completed a GC. Update the soft reference
3324 // policy with the new heap occupancy
3325 Universe::update_heap_info_at_gc();
3326 }
3327
3328 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3329 uint gc_count_before,
3330 bool* succeeded,
3331 GCCause::Cause gc_cause) {
3332 assert_heap_not_locked_and_not_at_safepoint();
3333 g1_policy()->record_stop_world_start();
3334 VM_G1IncCollectionPause op(gc_count_before,
3335 word_size,
3336 false, /* should_initiate_conc_mark */
3337 g1_policy()->max_pause_time_ms(),
3338 gc_cause);
3339
3340 op.set_allocation_context(AllocationContext::current());
3341 VMThread::execute(&op);
3342
3343 HeapWord* result = op.result();
3344 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3345 assert(result == NULL || ret_succeeded,
3346 "the result should be NULL if the VM did not succeed");
3347 *succeeded = ret_succeeded;
3348
3349 assert_heap_not_locked();
3350 return result;
3351 }
3352
3353 void
3354 G1CollectedHeap::doConcurrentMark() {
3355 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3356 if (!_cmThread->in_progress()) {
3357 _cmThread->set_started();
3358 CGC_lock->notify();
3359 }
3360 }
3361
3362 size_t G1CollectedHeap::pending_card_num() {
3363 size_t extra_cards = 0;
3364 JavaThread *curr = Threads::first();
3365 while (curr != NULL) {
3366 DirtyCardQueue& dcq = curr->dirty_card_queue();
3367 extra_cards += dcq.size();
3368 curr = curr->next();
3369 }
3370 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3371 size_t buffer_size = dcqs.buffer_size();
3372 size_t buffer_num = dcqs.completed_buffers_num();
3373
3374 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3375 // in bytes - not the number of 'entries'. We need to convert
3376 // into a number of cards.
3377 return (buffer_size * buffer_num + extra_cards) / oopSize;
3378 }
3379
3380 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3381 private:
3382 size_t _total_humongous;
3383 size_t _candidate_humongous;
3384
3385 DirtyCardQueue _dcq;
3386
3387 // We don't nominate objects with many remembered set entries, on
3388 // the assumption that such objects are likely still live.
3389 bool is_remset_small(HeapRegion* region) const {
3390 HeapRegionRemSet* const rset = region->rem_set();
3391 return G1EagerReclaimHumongousObjectsWithStaleRefs
3392 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3393 : rset->is_empty();
3394 }
3395
3396 bool is_typeArray_region(HeapRegion* region) const {
3397 return oop(region->bottom())->is_typeArray();
3398 }
3399
3400 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3401 assert(region->is_starts_humongous(), "Must start a humongous object");
3402
3403 // Candidate selection must satisfy the following constraints
3404 // while concurrent marking is in progress:
3405 //
3406 // * In order to maintain SATB invariants, an object must not be
3407 // reclaimed if it was allocated before the start of marking and
3408 // has not had its references scanned. Such an object must have
3409 // its references (including type metadata) scanned to ensure no
3410 // live objects are missed by the marking process. Objects
3411 // allocated after the start of concurrent marking don't need to
3412 // be scanned.
3413 //
3414 // * An object must not be reclaimed if it is on the concurrent
3415 // mark stack. Objects allocated after the start of concurrent
3416 // marking are never pushed on the mark stack.
3417 //
3418 // Nominating only objects allocated after the start of concurrent
3419 // marking is sufficient to meet both constraints. This may miss
3420 // some objects that satisfy the constraints, but the marking data
3421 // structures don't support efficiently performing the needed
3422 // additional tests or scrubbing of the mark stack.
3423 //
3424 // However, we presently only nominate is_typeArray() objects.
3425 // A humongous object containing references induces remembered
3426 // set entries on other regions. In order to reclaim such an
3427 // object, those remembered sets would need to be cleaned up.
3428 //
3429 // We also treat is_typeArray() objects specially, allowing them
3430 // to be reclaimed even if allocated before the start of
3431 // concurrent mark. For this we rely on mark stack insertion to
3432 // exclude is_typeArray() objects, preventing reclaiming an object
3433 // that is in the mark stack. We also rely on the metadata for
3434 // such objects to be built-in and so ensured to be kept live.
3435 // Frequent allocation and drop of large binary blobs is an
3436 // important use case for eager reclaim, and this special handling
3437 // may reduce needed headroom.
3438
3439 return is_typeArray_region(region) && is_remset_small(region);
3440 }
3441
3442 public:
3443 RegisterHumongousWithInCSetFastTestClosure()
3444 : _total_humongous(0),
3445 _candidate_humongous(0),
3446 _dcq(&JavaThread::dirty_card_queue_set()) {
3447 }
3448
3449 virtual bool doHeapRegion(HeapRegion* r) {
3450 if (!r->is_starts_humongous()) {
3451 return false;
3452 }
3453 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3454
3455 bool is_candidate = humongous_region_is_candidate(g1h, r);
3456 uint rindex = r->hrm_index();
3457 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3458 if (is_candidate) {
3459 _candidate_humongous++;
3460 g1h->register_humongous_region_with_cset(rindex);
3461 // Is_candidate already filters out humongous object with large remembered sets.
3462 // If we have a humongous object with a few remembered sets, we simply flush these
3463 // remembered set entries into the DCQS. That will result in automatic
3464 // re-evaluation of their remembered set entries during the following evacuation
3465 // phase.
3466 if (!r->rem_set()->is_empty()) {
3467 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3468 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3469 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3470 HeapRegionRemSetIterator hrrs(r->rem_set());
3471 size_t card_index;
3472 while (hrrs.has_next(card_index)) {
3473 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3474 // The remembered set might contain references to already freed
3475 // regions. Filter out such entries to avoid failing card table
3476 // verification.
3477 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3478 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3479 *card_ptr = CardTableModRefBS::dirty_card_val();
3480 _dcq.enqueue(card_ptr);
3481 }
3482 }
3483 }
3484 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3485 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3486 hrrs.n_yielded(), r->rem_set()->occupied());
3487 r->rem_set()->clear_locked();
3488 }
3489 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3490 }
3491 _total_humongous++;
3492
3493 return false;
3494 }
3495
3496 size_t total_humongous() const { return _total_humongous; }
3497 size_t candidate_humongous() const { return _candidate_humongous; }
3498
3499 void flush_rem_set_entries() { _dcq.flush(); }
3500 };
3501
3502 void G1CollectedHeap::register_humongous_regions_with_cset() {
3503 if (!G1EagerReclaimHumongousObjects) {
3504 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3505 return;
3506 }
3507 double time = os::elapsed_counter();
3508
3509 // Collect reclaim candidate information and register candidates with cset.
3510 RegisterHumongousWithInCSetFastTestClosure cl;
3511 heap_region_iterate(&cl);
3512
3513 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3514 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3515 cl.total_humongous(),
3516 cl.candidate_humongous());
3517 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3518
3519 // Finally flush all remembered set entries to re-check into the global DCQS.
3520 cl.flush_rem_set_entries();
3521 }
3522
3523 #ifdef ASSERT
3524 class VerifyCSetClosure: public HeapRegionClosure {
3525 public:
3526 bool doHeapRegion(HeapRegion* hr) {
3527 // Here we check that the CSet region's RSet is ready for parallel
3528 // iteration. The fields that we'll verify are only manipulated
3529 // when the region is part of a CSet and is collected. Afterwards,
3530 // we reset these fields when we clear the region's RSet (when the
3531 // region is freed) so they are ready when the region is
3532 // re-allocated. The only exception to this is if there's an
3533 // evacuation failure and instead of freeing the region we leave
3534 // it in the heap. In that case, we reset these fields during
3535 // evacuation failure handling.
3536 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3537
3538 // Here's a good place to add any other checks we'd like to
3539 // perform on CSet regions.
3540 return false;
3541 }
3542 };
3543 #endif // ASSERT
3544
3545 uint G1CollectedHeap::num_task_queues() const {
3546 return _task_queues->size();
3547 }
3548
3549 #if TASKQUEUE_STATS
3550 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3551 st->print_raw_cr("GC Task Stats");
3552 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3553 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3554 }
3555
3556 void G1CollectedHeap::print_taskqueue_stats() const {
3557 LogHandle(gc, task, stats) log;
3558 if (!log.is_develop()) {
3559 return;
3560 }
3561 ResourceMark rm;
3562 outputStream* st = log.develop_stream();
3563
3564 print_taskqueue_stats_hdr(st);
3565
3566 TaskQueueStats totals;
3567 const uint n = num_task_queues();
3568 for (uint i = 0; i < n; ++i) {
3569 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3570 totals += task_queue(i)->stats;
3571 }
3572 st->print_raw("tot "); totals.print(st); st->cr();
3573
3574 DEBUG_ONLY(totals.verify());
3575 }
3576
3577 void G1CollectedHeap::reset_taskqueue_stats() {
3578 const uint n = num_task_queues();
3579 for (uint i = 0; i < n; ++i) {
3580 task_queue(i)->stats.reset();
3581 }
3582 }
3583 #endif // TASKQUEUE_STATS
3584
3585 void G1CollectedHeap::log_gc_footer(double pause_time_counter) {
3586 if (evacuation_failed()) {
3587 log_info(gc)("To-space exhausted");
3588 }
3589
3590 double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
3591 g1_policy()->print_phases(pause_time_sec);
3592
3593 g1_policy()->print_detailed_heap_transition();
3594 }
3595
3596
3597 void G1CollectedHeap::wait_for_root_region_scanning() {
3598 double scan_wait_start = os::elapsedTime();
3599 // We have to wait until the CM threads finish scanning the
3600 // root regions as it's the only way to ensure that all the
3601 // objects on them have been correctly scanned before we start
3602 // moving them during the GC.
3603 bool waited = _cm->root_regions()->wait_until_scan_finished();
3604 double wait_time_ms = 0.0;
3605 if (waited) {
3606 double scan_wait_end = os::elapsedTime();
3607 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3608 }
3609 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3610 }
3611
3612 bool
3613 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3614 assert_at_safepoint(true /* should_be_vm_thread */);
3615 guarantee(!is_gc_active(), "collection is not reentrant");
3616
3617 if (GC_locker::check_active_before_gc()) {
3618 return false;
3619 }
3620
3621 _gc_timer_stw->register_gc_start();
3622
3623 GCIdMark gc_id_mark;
3624 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3625
3626 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3627 ResourceMark rm;
3628
3629 wait_for_root_region_scanning();
3630
3631 print_heap_before_gc();
3632 trace_heap_before_gc(_gc_tracer_stw);
3633
3634 verify_region_sets_optional();
3635 verify_dirty_young_regions();
3636
3637 // This call will decide whether this pause is an initial-mark
3638 // pause. If it is, during_initial_mark_pause() will return true
3639 // for the duration of this pause.
3640 g1_policy()->decide_on_conc_mark_initiation();
3641
3642 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3643 assert(!collector_state()->during_initial_mark_pause() ||
3644 collector_state()->gcs_are_young(), "sanity");
3645
3646 // We also do not allow mixed GCs during marking.
3647 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3648
3649 // Record whether this pause is an initial mark. When the current
3650 // thread has completed its logging output and it's safe to signal
3651 // the CM thread, the flag's value in the policy has been reset.
3652 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3653
3654 // Inner scope for scope based logging, timers, and stats collection
3655 {
3656 EvacuationInfo evacuation_info;
3657
3658 if (collector_state()->during_initial_mark_pause()) {
3659 // We are about to start a marking cycle, so we increment the
3660 // full collection counter.
3661 increment_old_marking_cycles_started();
3662 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3663 }
3664
3665 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3666
3667 GCTraceCPUTime tcpu;
3668
3669 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3670 workers()->active_workers(),
3671 Threads::number_of_non_daemon_threads());
3672 workers()->set_active_workers(active_workers);
3673 FormatBuffer<> gc_string("Pause ");
3674 if (collector_state()->during_initial_mark_pause()) {
3675 gc_string.append("Initial Mark");
3676 } else if (collector_state()->gcs_are_young()) {
3677 gc_string.append("Young");
3678 } else {
3679 gc_string.append("Mixed");
3680 }
3681 GCTraceTime(Info, gc) tm5(gc_string, NULL, gc_cause(), true);
3682
3683
3684 double pause_start_sec = os::elapsedTime();
3685 double pause_start_counter = os::elapsed_counter();
3686 g1_policy()->note_gc_start(active_workers);
3687
3688 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3689 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3690
3691 // If the secondary_free_list is not empty, append it to the
3692 // free_list. No need to wait for the cleanup operation to finish;
3693 // the region allocation code will check the secondary_free_list
3694 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3695 // set, skip this step so that the region allocation code has to
3696 // get entries from the secondary_free_list.
3697 if (!G1StressConcRegionFreeing) {
3698 append_secondary_free_list_if_not_empty_with_lock();
3699 }
3700
3701 assert(check_young_list_well_formed(), "young list should be well formed");
3702
3703 // Don't dynamically change the number of GC threads this early. A value of
3704 // 0 is used to indicate serial work. When parallel work is done,
3705 // it will be set.
3706
3707 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3708 IsGCActiveMark x;
3709
3710 gc_prologue(false);
3711 increment_total_collections(false /* full gc */);
3712 increment_gc_time_stamp();
3713
3714 verify_before_gc();
3715
3716 check_bitmaps("GC Start");
3717
3718 #if defined(COMPILER2) || INCLUDE_JVMCI
3719 DerivedPointerTable::clear();
3720 #endif
3721
3722 // Please see comment in g1CollectedHeap.hpp and
3723 // G1CollectedHeap::ref_processing_init() to see how
3724 // reference processing currently works in G1.
3725
3726 // Enable discovery in the STW reference processor
3727 ref_processor_stw()->enable_discovery();
3728
3729 {
3730 // We want to temporarily turn off discovery by the
3731 // CM ref processor, if necessary, and turn it back on
3732 // on again later if we do. Using a scoped
3733 // NoRefDiscovery object will do this.
3734 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3735
3736 // Forget the current alloc region (we might even choose it to be part
3737 // of the collection set!).
3738 _allocator->release_mutator_alloc_region();
3739
3740 // This timing is only used by the ergonomics to handle our pause target.
3741 // It is unclear why this should not include the full pause. We will
3742 // investigate this in CR 7178365.
3743 //
3744 // Preserving the old comment here if that helps the investigation:
3745 //
3746 // The elapsed time induced by the start time below deliberately elides
3747 // the possible verification above.
3748 double sample_start_time_sec = os::elapsedTime();
3749
3750 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3751
3752 if (collector_state()->during_initial_mark_pause()) {
3753 concurrent_mark()->checkpointRootsInitialPre();
3754 }
3755
3756 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3757 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3758
3759 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3760
3761 // Make sure the remembered sets are up to date. This needs to be
3762 // done before register_humongous_regions_with_cset(), because the
3763 // remembered sets are used there to choose eager reclaim candidates.
3764 // If the remembered sets are not up to date we might miss some
3765 // entries that need to be handled.
3766 g1_rem_set()->cleanupHRRS();
3767
3768 register_humongous_regions_with_cset();
3769
3770 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3771
3772 _cm->note_start_of_gc();
3773 // We call this after finalize_cset() to
3774 // ensure that the CSet has been finalized.
3775 _cm->verify_no_cset_oops();
3776
3777 if (_hr_printer.is_active()) {
3778 HeapRegion* hr = g1_policy()->collection_set();
3779 while (hr != NULL) {
3780 _hr_printer.cset(hr);
3781 hr = hr->next_in_collection_set();
3782 }
3783 }
3784
3785 #ifdef ASSERT
3786 VerifyCSetClosure cl;
3787 collection_set_iterate(&cl);
3788 #endif // ASSERT
3789
3790 // Initialize the GC alloc regions.
3791 _allocator->init_gc_alloc_regions(evacuation_info);
3792
3793 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3794 pre_evacuate_collection_set();
3795
3796 // Actually do the work...
3797 evacuate_collection_set(evacuation_info, &per_thread_states);
3798
3799 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3800
3801 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3802 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3803
3804 eagerly_reclaim_humongous_regions();
3805
3806 g1_policy()->clear_collection_set();
3807
3808 // Start a new incremental collection set for the next pause.
3809 g1_policy()->start_incremental_cset_building();
3810
3811 clear_cset_fast_test();
3812
3813 _young_list->reset_sampled_info();
3814
3815 // Don't check the whole heap at this point as the
3816 // GC alloc regions from this pause have been tagged
3817 // as survivors and moved on to the survivor list.
3818 // Survivor regions will fail the !is_young() check.
3819 assert(check_young_list_empty(false /* check_heap */),
3820 "young list should be empty");
3821
3822 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3823 _young_list->first_survivor_region(),
3824 _young_list->last_survivor_region());
3825
3826 _young_list->reset_auxilary_lists();
3827
3828 if (evacuation_failed()) {
3829 set_used(recalculate_used());
3830 if (_archive_allocator != NULL) {
3831 _archive_allocator->clear_used();
3832 }
3833 for (uint i = 0; i < ParallelGCThreads; i++) {
3834 if (_evacuation_failed_info_array[i].has_failed()) {
3835 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3836 }
3837 }
3838 } else {
3839 // The "used" of the the collection set have already been subtracted
3840 // when they were freed. Add in the bytes evacuated.
3841 increase_used(g1_policy()->bytes_copied_during_gc());
3842 }
3843
3844 if (collector_state()->during_initial_mark_pause()) {
3845 // We have to do this before we notify the CM threads that
3846 // they can start working to make sure that all the
3847 // appropriate initialization is done on the CM object.
3848 concurrent_mark()->checkpointRootsInitialPost();
3849 collector_state()->set_mark_in_progress(true);
3850 // Note that we don't actually trigger the CM thread at
3851 // this point. We do that later when we're sure that
3852 // the current thread has completed its logging output.
3853 }
3854
3855 allocate_dummy_regions();
3856
3857 _allocator->init_mutator_alloc_region();
3858
3859 {
3860 size_t expand_bytes = g1_policy()->expansion_amount();
3861 if (expand_bytes > 0) {
3862 size_t bytes_before = capacity();
3863 // No need for an ergo logging here,
3864 // expansion_amount() does this when it returns a value > 0.
3865 double expand_ms;
3866 if (!expand(expand_bytes, &expand_ms)) {
3867 // We failed to expand the heap. Cannot do anything about it.
3868 }
3869 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3870 }
3871 }
3872
3873 // We redo the verification but now wrt to the new CSet which
3874 // has just got initialized after the previous CSet was freed.
3875 _cm->verify_no_cset_oops();
3876 _cm->note_end_of_gc();
3877
3878 // This timing is only used by the ergonomics to handle our pause target.
3879 // It is unclear why this should not include the full pause. We will
3880 // investigate this in CR 7178365.
3881 double sample_end_time_sec = os::elapsedTime();
3882 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3883 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3884 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3885
3886 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3887 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3888
3889 MemoryService::track_memory_usage();
3890
3891 // In prepare_for_verify() below we'll need to scan the deferred
3892 // update buffers to bring the RSets up-to-date if
3893 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3894 // the update buffers we'll probably need to scan cards on the
3895 // regions we just allocated to (i.e., the GC alloc
3896 // regions). However, during the last GC we called
3897 // set_saved_mark() on all the GC alloc regions, so card
3898 // scanning might skip the [saved_mark_word()...top()] area of
3899 // those regions (i.e., the area we allocated objects into
3900 // during the last GC). But it shouldn't. Given that
3901 // saved_mark_word() is conditional on whether the GC time stamp
3902 // on the region is current or not, by incrementing the GC time
3903 // stamp here we invalidate all the GC time stamps on all the
3904 // regions and saved_mark_word() will simply return top() for
3905 // all the regions. This is a nicer way of ensuring this rather
3906 // than iterating over the regions and fixing them. In fact, the
3907 // GC time stamp increment here also ensures that
3908 // saved_mark_word() will return top() between pauses, i.e.,
3909 // during concurrent refinement. So we don't need the
3910 // is_gc_active() check to decided which top to use when
3911 // scanning cards (see CR 7039627).
3912 increment_gc_time_stamp();
3913
3914 verify_after_gc();
3915 check_bitmaps("GC End");
3916
3917 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3918 ref_processor_stw()->verify_no_references_recorded();
3919
3920 // CM reference discovery will be re-enabled if necessary.
3921 }
3922
3923 #ifdef TRACESPINNING
3924 ParallelTaskTerminator::print_termination_counts();
3925 #endif
3926
3927 gc_epilogue(false);
3928 }
3929
3930 // Print the remainder of the GC log output.
3931 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3932
3933 // It is not yet to safe to tell the concurrent mark to
3934 // start as we have some optional output below. We don't want the
3935 // output from the concurrent mark thread interfering with this
3936 // logging output either.
3937
3938 _hrm.verify_optional();
3939 verify_region_sets_optional();
3940
3941 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3942 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3943
3944 print_heap_after_gc();
3945 trace_heap_after_gc(_gc_tracer_stw);
3946
3947 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3948 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3949 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3950 // before any GC notifications are raised.
3951 g1mm()->update_sizes();
3952
3953 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3954 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3955 _gc_timer_stw->register_gc_end();
3956 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3957 }
3958 // It should now be safe to tell the concurrent mark thread to start
3959 // without its logging output interfering with the logging output
3960 // that came from the pause.
3961
3962 if (should_start_conc_mark) {
3963 // CAUTION: after the doConcurrentMark() call below,
3964 // the concurrent marking thread(s) could be running
3965 // concurrently with us. Make sure that anything after
3966 // this point does not assume that we are the only GC thread
3967 // running. Note: of course, the actual marking work will
3968 // not start until the safepoint itself is released in
3969 // SuspendibleThreadSet::desynchronize().
3970 doConcurrentMark();
3971 }
3972
3973 return true;
3974 }
3975
3976 void G1CollectedHeap::remove_self_forwarding_pointers() {
3977 double remove_self_forwards_start = os::elapsedTime();
3978
3979 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3980 workers()->run_task(&rsfp_task);
3981
3982 // Now restore saved marks, if any.
3983 for (uint i = 0; i < ParallelGCThreads; i++) {
3984 OopAndMarkOopStack& cur = _preserved_objs[i];
3985 while (!cur.is_empty()) {
3986 OopAndMarkOop elem = cur.pop();
3987 elem.set_mark();
3988 }
3989 cur.clear(true);
3990 }
3991
3992 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3993 }
3994
3995 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3996 if (!_evacuation_failed) {
3997 _evacuation_failed = true;
3998 }
3999
4000 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4001
4002 // We want to call the "for_promotion_failure" version only in the
4003 // case of a promotion failure.
4004 if (m->must_be_preserved_for_promotion_failure(obj)) {
4005 OopAndMarkOop elem(obj, m);
4006 _preserved_objs[worker_id].push(elem);
4007 }
4008 }
4009
4010 class G1ParEvacuateFollowersClosure : public VoidClosure {
4011 private:
4012 double _start_term;
4013 double _term_time;
4014 size_t _term_attempts;
4015
4016 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4017 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4018 protected:
4019 G1CollectedHeap* _g1h;
4020 G1ParScanThreadState* _par_scan_state;
4021 RefToScanQueueSet* _queues;
4022 ParallelTaskTerminator* _terminator;
4023
4024 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4025 RefToScanQueueSet* queues() { return _queues; }
4026 ParallelTaskTerminator* terminator() { return _terminator; }
4027
4028 public:
4029 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4030 G1ParScanThreadState* par_scan_state,
4031 RefToScanQueueSet* queues,
4032 ParallelTaskTerminator* terminator)
4033 : _g1h(g1h), _par_scan_state(par_scan_state),
4034 _queues(queues), _terminator(terminator),
4035 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4036
4037 void do_void();
4038
4039 double term_time() const { return _term_time; }
4040 size_t term_attempts() const { return _term_attempts; }
4041
4042 private:
4043 inline bool offer_termination();
4044 };
4045
4046 bool G1ParEvacuateFollowersClosure::offer_termination() {
4047 G1ParScanThreadState* const pss = par_scan_state();
4048 start_term_time();
4049 const bool res = terminator()->offer_termination();
4050 end_term_time();
4051 return res;
4052 }
4053
4054 void G1ParEvacuateFollowersClosure::do_void() {
4055 G1ParScanThreadState* const pss = par_scan_state();
4056 pss->trim_queue();
4057 do {
4058 pss->steal_and_trim_queue(queues());
4059 } while (!offer_termination());
4060 }
4061
4062 class G1ParTask : public AbstractGangTask {
4063 protected:
4064 G1CollectedHeap* _g1h;
4065 G1ParScanThreadStateSet* _pss;
4066 RefToScanQueueSet* _queues;
4067 G1RootProcessor* _root_processor;
4068 ParallelTaskTerminator _terminator;
4069 uint _n_workers;
4070
4071 public:
4072 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4073 : AbstractGangTask("G1 collection"),
4074 _g1h(g1h),
4075 _pss(per_thread_states),
4076 _queues(task_queues),
4077 _root_processor(root_processor),
4078 _terminator(n_workers, _queues),
4079 _n_workers(n_workers)
4080 {}
4081
4082 void work(uint worker_id) {
4083 if (worker_id >= _n_workers) return; // no work needed this round
4084
4085 double start_sec = os::elapsedTime();
4086 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4087
4088 {
4089 ResourceMark rm;
4090 HandleMark hm;
4091
4092 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4093
4094 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4095 pss->set_ref_processor(rp);
4096
4097 double start_strong_roots_sec = os::elapsedTime();
4098
4099 _root_processor->evacuate_roots(pss->closures(), worker_id);
4100
4101 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4102
4103 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4104 // treating the nmethods visited to act as roots for concurrent marking.
4105 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4106 // objects copied by the current evacuation.
4107 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4108 pss->closures()->weak_codeblobs(),
4109 worker_id);
4110
4111 _pss->add_cards_scanned(worker_id, cards_scanned);
4112
4113 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4114
4115 double term_sec = 0.0;
4116 size_t evac_term_attempts = 0;
4117 {
4118 double start = os::elapsedTime();
4119 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4120 evac.do_void();
4121
4122 evac_term_attempts = evac.term_attempts();
4123 term_sec = evac.term_time();
4124 double elapsed_sec = os::elapsedTime() - start;
4125 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4126 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4127 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4128 }
4129
4130 assert(pss->queue_is_empty(), "should be empty");
4131
4132 if (log_is_enabled(Debug, gc, task, stats)) {
4133 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4134 size_t lab_waste;
4135 size_t lab_undo_waste;
4136 pss->waste(lab_waste, lab_undo_waste);
4137 _g1h->print_termination_stats(worker_id,
4138 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4139 strong_roots_sec * 1000.0, /* strong roots time */
4140 term_sec * 1000.0, /* evac term time */
4141 evac_term_attempts, /* evac term attempts */
4142 lab_waste, /* alloc buffer waste */
4143 lab_undo_waste /* undo waste */
4144 );
4145 }
4146
4147 // Close the inner scope so that the ResourceMark and HandleMark
4148 // destructors are executed here and are included as part of the
4149 // "GC Worker Time".
4150 }
4151 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4152 }
4153 };
4154
4155 void G1CollectedHeap::print_termination_stats_hdr() {
4156 LogHandle(gc, task, stats) log;
4157 if (!log.is_debug()) {
4158 return;
4159 }
4160 log.debug("GC Termination Stats");
4161 log.debug(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4162 log.debug("thr ms ms %% ms %% attempts total alloc undo");
4163 log.debug("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4164 }
4165
4166 void G1CollectedHeap::print_termination_stats(uint worker_id,
4167 double elapsed_ms,
4168 double strong_roots_ms,
4169 double term_ms,
4170 size_t term_attempts,
4171 size_t alloc_buffer_waste,
4172 size_t undo_waste) const {
4173 log_debug(gc, task, stats)
4174 ("%3d %9.2f %9.2f %6.2f "
4175 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4176 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4177 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4178 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4179 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4180 alloc_buffer_waste * HeapWordSize / K,
4181 undo_waste * HeapWordSize / K);
4182 }
4183
4184 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4185 private:
4186 BoolObjectClosure* _is_alive;
4187 int _initial_string_table_size;
4188 int _initial_symbol_table_size;
4189
4190 bool _process_strings;
4191 int _strings_processed;
4192 int _strings_removed;
4193
4194 bool _process_symbols;
4195 int _symbols_processed;
4196 int _symbols_removed;
4197
4198 public:
4199 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4200 AbstractGangTask("String/Symbol Unlinking"),
4201 _is_alive(is_alive),
4202 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4203 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4204
4205 _initial_string_table_size = StringTable::the_table()->table_size();
4206 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4207 if (process_strings) {
4208 StringTable::clear_parallel_claimed_index();
4209 }
4210 if (process_symbols) {
4211 SymbolTable::clear_parallel_claimed_index();
4212 }
4213 }
4214
4215 ~G1StringSymbolTableUnlinkTask() {
4216 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4217 "claim value %d after unlink less than initial string table size %d",
4218 StringTable::parallel_claimed_index(), _initial_string_table_size);
4219 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4220 "claim value %d after unlink less than initial symbol table size %d",
4221 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4222
4223 log_trace(gc, stringdedup)("Cleaned string and symbol table, "
4224 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4225 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4226 strings_processed(), strings_removed(),
4227 symbols_processed(), symbols_removed());
4228 }
4229
4230 void work(uint worker_id) {
4231 int strings_processed = 0;
4232 int strings_removed = 0;
4233 int symbols_processed = 0;
4234 int symbols_removed = 0;
4235 if (_process_strings) {
4236 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4237 Atomic::add(strings_processed, &_strings_processed);
4238 Atomic::add(strings_removed, &_strings_removed);
4239 }
4240 if (_process_symbols) {
4241 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4242 Atomic::add(symbols_processed, &_symbols_processed);
4243 Atomic::add(symbols_removed, &_symbols_removed);
4244 }
4245 }
4246
4247 size_t strings_processed() const { return (size_t)_strings_processed; }
4248 size_t strings_removed() const { return (size_t)_strings_removed; }
4249
4250 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4251 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4252 };
4253
4254 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4255 private:
4256 static Monitor* _lock;
4257
4258 BoolObjectClosure* const _is_alive;
4259 const bool _unloading_occurred;
4260 const uint _num_workers;
4261
4262 // Variables used to claim nmethods.
4263 nmethod* _first_nmethod;
4264 volatile nmethod* _claimed_nmethod;
4265
4266 // The list of nmethods that need to be processed by the second pass.
4267 volatile nmethod* _postponed_list;
4268 volatile uint _num_entered_barrier;
4269
4270 public:
4271 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4272 _is_alive(is_alive),
4273 _unloading_occurred(unloading_occurred),
4274 _num_workers(num_workers),
4275 _first_nmethod(NULL),
4276 _claimed_nmethod(NULL),
4277 _postponed_list(NULL),
4278 _num_entered_barrier(0)
4279 {
4280 nmethod::increase_unloading_clock();
4281 // Get first alive nmethod
4282 NMethodIterator iter = NMethodIterator();
4283 if(iter.next_alive()) {
4284 _first_nmethod = iter.method();
4285 }
4286 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4287 }
4288
4289 ~G1CodeCacheUnloadingTask() {
4290 CodeCache::verify_clean_inline_caches();
4291
4292 CodeCache::set_needs_cache_clean(false);
4293 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4294
4295 CodeCache::verify_icholder_relocations();
4296 }
4297
4298 private:
4299 void add_to_postponed_list(nmethod* nm) {
4300 nmethod* old;
4301 do {
4302 old = (nmethod*)_postponed_list;
4303 nm->set_unloading_next(old);
4304 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4305 }
4306
4307 void clean_nmethod(nmethod* nm) {
4308 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4309
4310 if (postponed) {
4311 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4312 add_to_postponed_list(nm);
4313 }
4314
4315 // Mark that this thread has been cleaned/unloaded.
4316 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4317 nm->set_unloading_clock(nmethod::global_unloading_clock());
4318 }
4319
4320 void clean_nmethod_postponed(nmethod* nm) {
4321 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4322 }
4323
4324 static const int MaxClaimNmethods = 16;
4325
4326 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4327 nmethod* first;
4328 NMethodIterator last;
4329
4330 do {
4331 *num_claimed_nmethods = 0;
4332
4333 first = (nmethod*)_claimed_nmethod;
4334 last = NMethodIterator(first);
4335
4336 if (first != NULL) {
4337
4338 for (int i = 0; i < MaxClaimNmethods; i++) {
4339 if (!last.next_alive()) {
4340 break;
4341 }
4342 claimed_nmethods[i] = last.method();
4343 (*num_claimed_nmethods)++;
4344 }
4345 }
4346
4347 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4348 }
4349
4350 nmethod* claim_postponed_nmethod() {
4351 nmethod* claim;
4352 nmethod* next;
4353
4354 do {
4355 claim = (nmethod*)_postponed_list;
4356 if (claim == NULL) {
4357 return NULL;
4358 }
4359
4360 next = claim->unloading_next();
4361
4362 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4363
4364 return claim;
4365 }
4366
4367 public:
4368 // Mark that we're done with the first pass of nmethod cleaning.
4369 void barrier_mark(uint worker_id) {
4370 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4371 _num_entered_barrier++;
4372 if (_num_entered_barrier == _num_workers) {
4373 ml.notify_all();
4374 }
4375 }
4376
4377 // See if we have to wait for the other workers to
4378 // finish their first-pass nmethod cleaning work.
4379 void barrier_wait(uint worker_id) {
4380 if (_num_entered_barrier < _num_workers) {
4381 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4382 while (_num_entered_barrier < _num_workers) {
4383 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4384 }
4385 }
4386 }
4387
4388 // Cleaning and unloading of nmethods. Some work has to be postponed
4389 // to the second pass, when we know which nmethods survive.
4390 void work_first_pass(uint worker_id) {
4391 // The first nmethods is claimed by the first worker.
4392 if (worker_id == 0 && _first_nmethod != NULL) {
4393 clean_nmethod(_first_nmethod);
4394 _first_nmethod = NULL;
4395 }
4396
4397 int num_claimed_nmethods;
4398 nmethod* claimed_nmethods[MaxClaimNmethods];
4399
4400 while (true) {
4401 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4402
4403 if (num_claimed_nmethods == 0) {
4404 break;
4405 }
4406
4407 for (int i = 0; i < num_claimed_nmethods; i++) {
4408 clean_nmethod(claimed_nmethods[i]);
4409 }
4410 }
4411 }
4412
4413 void work_second_pass(uint worker_id) {
4414 nmethod* nm;
4415 // Take care of postponed nmethods.
4416 while ((nm = claim_postponed_nmethod()) != NULL) {
4417 clean_nmethod_postponed(nm);
4418 }
4419 }
4420 };
4421
4422 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4423
4424 class G1KlassCleaningTask : public StackObj {
4425 BoolObjectClosure* _is_alive;
4426 volatile jint _clean_klass_tree_claimed;
4427 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4428
4429 public:
4430 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4431 _is_alive(is_alive),
4432 _clean_klass_tree_claimed(0),
4433 _klass_iterator() {
4434 }
4435
4436 private:
4437 bool claim_clean_klass_tree_task() {
4438 if (_clean_klass_tree_claimed) {
4439 return false;
4440 }
4441
4442 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4443 }
4444
4445 InstanceKlass* claim_next_klass() {
4446 Klass* klass;
4447 do {
4448 klass =_klass_iterator.next_klass();
4449 } while (klass != NULL && !klass->is_instance_klass());
4450
4451 // this can be null so don't call InstanceKlass::cast
4452 return static_cast<InstanceKlass*>(klass);
4453 }
4454
4455 public:
4456
4457 void clean_klass(InstanceKlass* ik) {
4458 ik->clean_weak_instanceklass_links(_is_alive);
4459 }
4460
4461 void work() {
4462 ResourceMark rm;
4463
4464 // One worker will clean the subklass/sibling klass tree.
4465 if (claim_clean_klass_tree_task()) {
4466 Klass::clean_subklass_tree(_is_alive);
4467 }
4468
4469 // All workers will help cleaning the classes,
4470 InstanceKlass* klass;
4471 while ((klass = claim_next_klass()) != NULL) {
4472 clean_klass(klass);
4473 }
4474 }
4475 };
4476
4477 // To minimize the remark pause times, the tasks below are done in parallel.
4478 class G1ParallelCleaningTask : public AbstractGangTask {
4479 private:
4480 G1StringSymbolTableUnlinkTask _string_symbol_task;
4481 G1CodeCacheUnloadingTask _code_cache_task;
4482 G1KlassCleaningTask _klass_cleaning_task;
4483
4484 public:
4485 // The constructor is run in the VMThread.
4486 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4487 AbstractGangTask("Parallel Cleaning"),
4488 _string_symbol_task(is_alive, process_strings, process_symbols),
4489 _code_cache_task(num_workers, is_alive, unloading_occurred),
4490 _klass_cleaning_task(is_alive) {
4491 }
4492
4493 // The parallel work done by all worker threads.
4494 void work(uint worker_id) {
4495 // Do first pass of code cache cleaning.
4496 _code_cache_task.work_first_pass(worker_id);
4497
4498 // Let the threads mark that the first pass is done.
4499 _code_cache_task.barrier_mark(worker_id);
4500
4501 // Clean the Strings and Symbols.
4502 _string_symbol_task.work(worker_id);
4503
4504 // Wait for all workers to finish the first code cache cleaning pass.
4505 _code_cache_task.barrier_wait(worker_id);
4506
4507 // Do the second code cache cleaning work, which realize on
4508 // the liveness information gathered during the first pass.
4509 _code_cache_task.work_second_pass(worker_id);
4510
4511 // Clean all klasses that were not unloaded.
4512 _klass_cleaning_task.work();
4513 }
4514 };
4515
4516
4517 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4518 bool process_strings,
4519 bool process_symbols,
4520 bool class_unloading_occurred) {
4521 uint n_workers = workers()->active_workers();
4522
4523 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4524 n_workers, class_unloading_occurred);
4525 workers()->run_task(&g1_unlink_task);
4526 }
4527
4528 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4529 bool process_strings, bool process_symbols) {
4530 {
4531 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4532 workers()->run_task(&g1_unlink_task);
4533 }
4534
4535 if (G1StringDedup::is_enabled()) {
4536 G1StringDedup::unlink(is_alive);
4537 }
4538 }
4539
4540 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4541 private:
4542 DirtyCardQueueSet* _queue;
4543 public:
4544 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4545
4546 virtual void work(uint worker_id) {
4547 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4548 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4549
4550 RedirtyLoggedCardTableEntryClosure cl;
4551 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4552
4553 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4554 }
4555 };
4556
4557 void G1CollectedHeap::redirty_logged_cards() {
4558 double redirty_logged_cards_start = os::elapsedTime();
4559
4560 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4561 dirty_card_queue_set().reset_for_par_iteration();
4562 workers()->run_task(&redirty_task);
4563
4564 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4565 dcq.merge_bufferlists(&dirty_card_queue_set());
4566 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4567
4568 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4569 }
4570
4571 // Weak Reference Processing support
4572
4573 // An always "is_alive" closure that is used to preserve referents.
4574 // If the object is non-null then it's alive. Used in the preservation
4575 // of referent objects that are pointed to by reference objects
4576 // discovered by the CM ref processor.
4577 class G1AlwaysAliveClosure: public BoolObjectClosure {
4578 G1CollectedHeap* _g1;
4579 public:
4580 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4581 bool do_object_b(oop p) {
4582 if (p != NULL) {
4583 return true;
4584 }
4585 return false;
4586 }
4587 };
4588
4589 bool G1STWIsAliveClosure::do_object_b(oop p) {
4590 // An object is reachable if it is outside the collection set,
4591 // or is inside and copied.
4592 return !_g1->is_in_cset(p) || p->is_forwarded();
4593 }
4594
4595 // Non Copying Keep Alive closure
4596 class G1KeepAliveClosure: public OopClosure {
4597 G1CollectedHeap* _g1;
4598 public:
4599 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4600 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4601 void do_oop(oop* p) {
4602 oop obj = *p;
4603 assert(obj != NULL, "the caller should have filtered out NULL values");
4604
4605 const InCSetState cset_state = _g1->in_cset_state(obj);
4606 if (!cset_state.is_in_cset_or_humongous()) {
4607 return;
4608 }
4609 if (cset_state.is_in_cset()) {
4610 assert( obj->is_forwarded(), "invariant" );
4611 *p = obj->forwardee();
4612 } else {
4613 assert(!obj->is_forwarded(), "invariant" );
4614 assert(cset_state.is_humongous(),
4615 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4616 _g1->set_humongous_is_live(obj);
4617 }
4618 }
4619 };
4620
4621 // Copying Keep Alive closure - can be called from both
4622 // serial and parallel code as long as different worker
4623 // threads utilize different G1ParScanThreadState instances
4624 // and different queues.
4625
4626 class G1CopyingKeepAliveClosure: public OopClosure {
4627 G1CollectedHeap* _g1h;
4628 OopClosure* _copy_non_heap_obj_cl;
4629 G1ParScanThreadState* _par_scan_state;
4630
4631 public:
4632 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4633 OopClosure* non_heap_obj_cl,
4634 G1ParScanThreadState* pss):
4635 _g1h(g1h),
4636 _copy_non_heap_obj_cl(non_heap_obj_cl),
4637 _par_scan_state(pss)
4638 {}
4639
4640 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4641 virtual void do_oop( oop* p) { do_oop_work(p); }
4642
4643 template <class T> void do_oop_work(T* p) {
4644 oop obj = oopDesc::load_decode_heap_oop(p);
4645
4646 if (_g1h->is_in_cset_or_humongous(obj)) {
4647 // If the referent object has been forwarded (either copied
4648 // to a new location or to itself in the event of an
4649 // evacuation failure) then we need to update the reference
4650 // field and, if both reference and referent are in the G1
4651 // heap, update the RSet for the referent.
4652 //
4653 // If the referent has not been forwarded then we have to keep
4654 // it alive by policy. Therefore we have copy the referent.
4655 //
4656 // If the reference field is in the G1 heap then we can push
4657 // on the PSS queue. When the queue is drained (after each
4658 // phase of reference processing) the object and it's followers
4659 // will be copied, the reference field set to point to the
4660 // new location, and the RSet updated. Otherwise we need to
4661 // use the the non-heap or metadata closures directly to copy
4662 // the referent object and update the pointer, while avoiding
4663 // updating the RSet.
4664
4665 if (_g1h->is_in_g1_reserved(p)) {
4666 _par_scan_state->push_on_queue(p);
4667 } else {
4668 assert(!Metaspace::contains((const void*)p),
4669 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4670 _copy_non_heap_obj_cl->do_oop(p);
4671 }
4672 }
4673 }
4674 };
4675
4676 // Serial drain queue closure. Called as the 'complete_gc'
4677 // closure for each discovered list in some of the
4678 // reference processing phases.
4679
4680 class G1STWDrainQueueClosure: public VoidClosure {
4681 protected:
4682 G1CollectedHeap* _g1h;
4683 G1ParScanThreadState* _par_scan_state;
4684
4685 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4686
4687 public:
4688 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4689 _g1h(g1h),
4690 _par_scan_state(pss)
4691 { }
4692
4693 void do_void() {
4694 G1ParScanThreadState* const pss = par_scan_state();
4695 pss->trim_queue();
4696 }
4697 };
4698
4699 // Parallel Reference Processing closures
4700
4701 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4702 // processing during G1 evacuation pauses.
4703
4704 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4705 private:
4706 G1CollectedHeap* _g1h;
4707 G1ParScanThreadStateSet* _pss;
4708 RefToScanQueueSet* _queues;
4709 WorkGang* _workers;
4710 uint _active_workers;
4711
4712 public:
4713 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4714 G1ParScanThreadStateSet* per_thread_states,
4715 WorkGang* workers,
4716 RefToScanQueueSet *task_queues,
4717 uint n_workers) :
4718 _g1h(g1h),
4719 _pss(per_thread_states),
4720 _queues(task_queues),
4721 _workers(workers),
4722 _active_workers(n_workers)
4723 {
4724 assert(n_workers > 0, "shouldn't call this otherwise");
4725 }
4726
4727 // Executes the given task using concurrent marking worker threads.
4728 virtual void execute(ProcessTask& task);
4729 virtual void execute(EnqueueTask& task);
4730 };
4731
4732 // Gang task for possibly parallel reference processing
4733
4734 class G1STWRefProcTaskProxy: public AbstractGangTask {
4735 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4736 ProcessTask& _proc_task;
4737 G1CollectedHeap* _g1h;
4738 G1ParScanThreadStateSet* _pss;
4739 RefToScanQueueSet* _task_queues;
4740 ParallelTaskTerminator* _terminator;
4741
4742 public:
4743 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4744 G1CollectedHeap* g1h,
4745 G1ParScanThreadStateSet* per_thread_states,
4746 RefToScanQueueSet *task_queues,
4747 ParallelTaskTerminator* terminator) :
4748 AbstractGangTask("Process reference objects in parallel"),
4749 _proc_task(proc_task),
4750 _g1h(g1h),
4751 _pss(per_thread_states),
4752 _task_queues(task_queues),
4753 _terminator(terminator)
4754 {}
4755
4756 virtual void work(uint worker_id) {
4757 // The reference processing task executed by a single worker.
4758 ResourceMark rm;
4759 HandleMark hm;
4760
4761 G1STWIsAliveClosure is_alive(_g1h);
4762
4763 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4764 pss->set_ref_processor(NULL);
4765
4766 // Keep alive closure.
4767 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4768
4769 // Complete GC closure
4770 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4771
4772 // Call the reference processing task's work routine.
4773 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4774
4775 // Note we cannot assert that the refs array is empty here as not all
4776 // of the processing tasks (specifically phase2 - pp2_work) execute
4777 // the complete_gc closure (which ordinarily would drain the queue) so
4778 // the queue may not be empty.
4779 }
4780 };
4781
4782 // Driver routine for parallel reference processing.
4783 // Creates an instance of the ref processing gang
4784 // task and has the worker threads execute it.
4785 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4786 assert(_workers != NULL, "Need parallel worker threads.");
4787
4788 ParallelTaskTerminator terminator(_active_workers, _queues);
4789 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4790
4791 _workers->run_task(&proc_task_proxy);
4792 }
4793
4794 // Gang task for parallel reference enqueueing.
4795
4796 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4797 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4798 EnqueueTask& _enq_task;
4799
4800 public:
4801 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4802 AbstractGangTask("Enqueue reference objects in parallel"),
4803 _enq_task(enq_task)
4804 { }
4805
4806 virtual void work(uint worker_id) {
4807 _enq_task.work(worker_id);
4808 }
4809 };
4810
4811 // Driver routine for parallel reference enqueueing.
4812 // Creates an instance of the ref enqueueing gang
4813 // task and has the worker threads execute it.
4814
4815 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4816 assert(_workers != NULL, "Need parallel worker threads.");
4817
4818 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4819
4820 _workers->run_task(&enq_task_proxy);
4821 }
4822
4823 // End of weak reference support closures
4824
4825 // Abstract task used to preserve (i.e. copy) any referent objects
4826 // that are in the collection set and are pointed to by reference
4827 // objects discovered by the CM ref processor.
4828
4829 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4830 protected:
4831 G1CollectedHeap* _g1h;
4832 G1ParScanThreadStateSet* _pss;
4833 RefToScanQueueSet* _queues;
4834 ParallelTaskTerminator _terminator;
4835 uint _n_workers;
4836
4837 public:
4838 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4839 AbstractGangTask("ParPreserveCMReferents"),
4840 _g1h(g1h),
4841 _pss(per_thread_states),
4842 _queues(task_queues),
4843 _terminator(workers, _queues),
4844 _n_workers(workers)
4845 { }
4846
4847 void work(uint worker_id) {
4848 ResourceMark rm;
4849 HandleMark hm;
4850
4851 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4852 pss->set_ref_processor(NULL);
4853 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4854
4855 // Is alive closure
4856 G1AlwaysAliveClosure always_alive(_g1h);
4857
4858 // Copying keep alive closure. Applied to referent objects that need
4859 // to be copied.
4860 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4861
4862 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4863
4864 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4865 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4866
4867 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4868 // So this must be true - but assert just in case someone decides to
4869 // change the worker ids.
4870 assert(worker_id < limit, "sanity");
4871 assert(!rp->discovery_is_atomic(), "check this code");
4872
4873 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4874 for (uint idx = worker_id; idx < limit; idx += stride) {
4875 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4876
4877 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4878 while (iter.has_next()) {
4879 // Since discovery is not atomic for the CM ref processor, we
4880 // can see some null referent objects.
4881 iter.load_ptrs(DEBUG_ONLY(true));
4882 oop ref = iter.obj();
4883
4884 // This will filter nulls.
4885 if (iter.is_referent_alive()) {
4886 iter.make_referent_alive();
4887 }
4888 iter.move_to_next();
4889 }
4890 }
4891
4892 // Drain the queue - which may cause stealing
4893 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4894 drain_queue.do_void();
4895 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4896 assert(pss->queue_is_empty(), "should be");
4897 }
4898 };
4899
4900 // Weak Reference processing during an evacuation pause (part 1).
4901 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4902 double ref_proc_start = os::elapsedTime();
4903
4904 ReferenceProcessor* rp = _ref_processor_stw;
4905 assert(rp->discovery_enabled(), "should have been enabled");
4906
4907 // Any reference objects, in the collection set, that were 'discovered'
4908 // by the CM ref processor should have already been copied (either by
4909 // applying the external root copy closure to the discovered lists, or
4910 // by following an RSet entry).
4911 //
4912 // But some of the referents, that are in the collection set, that these
4913 // reference objects point to may not have been copied: the STW ref
4914 // processor would have seen that the reference object had already
4915 // been 'discovered' and would have skipped discovering the reference,
4916 // but would not have treated the reference object as a regular oop.
4917 // As a result the copy closure would not have been applied to the
4918 // referent object.
4919 //
4920 // We need to explicitly copy these referent objects - the references
4921 // will be processed at the end of remarking.
4922 //
4923 // We also need to do this copying before we process the reference
4924 // objects discovered by the STW ref processor in case one of these
4925 // referents points to another object which is also referenced by an
4926 // object discovered by the STW ref processor.
4927
4928 uint no_of_gc_workers = workers()->active_workers();
4929
4930 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4931 per_thread_states,
4932 no_of_gc_workers,
4933 _task_queues);
4934
4935 workers()->run_task(&keep_cm_referents);
4936
4937 // Closure to test whether a referent is alive.
4938 G1STWIsAliveClosure is_alive(this);
4939
4940 // Even when parallel reference processing is enabled, the processing
4941 // of JNI refs is serial and performed serially by the current thread
4942 // rather than by a worker. The following PSS will be used for processing
4943 // JNI refs.
4944
4945 // Use only a single queue for this PSS.
4946 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4947 pss->set_ref_processor(NULL);
4948 assert(pss->queue_is_empty(), "pre-condition");
4949
4950 // Keep alive closure.
4951 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4952
4953 // Serial Complete GC closure
4954 G1STWDrainQueueClosure drain_queue(this, pss);
4955
4956 // Setup the soft refs policy...
4957 rp->setup_policy(false);
4958
4959 ReferenceProcessorStats stats;
4960 if (!rp->processing_is_mt()) {
4961 // Serial reference processing...
4962 stats = rp->process_discovered_references(&is_alive,
4963 &keep_alive,
4964 &drain_queue,
4965 NULL,
4966 _gc_timer_stw);
4967 } else {
4968 // Parallel reference processing
4969 assert(rp->num_q() == no_of_gc_workers, "sanity");
4970 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4971
4972 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4973 stats = rp->process_discovered_references(&is_alive,
4974 &keep_alive,
4975 &drain_queue,
4976 &par_task_executor,
4977 _gc_timer_stw);
4978 }
4979
4980 _gc_tracer_stw->report_gc_reference_stats(stats);
4981
4982 // We have completed copying any necessary live referent objects.
4983 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4984
4985 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4986 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4987 }
4988
4989 // Weak Reference processing during an evacuation pause (part 2).
4990 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4991 double ref_enq_start = os::elapsedTime();
4992
4993 ReferenceProcessor* rp = _ref_processor_stw;
4994 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4995
4996 // Now enqueue any remaining on the discovered lists on to
4997 // the pending list.
4998 if (!rp->processing_is_mt()) {
4999 // Serial reference processing...
5000 rp->enqueue_discovered_references();
5001 } else {
5002 // Parallel reference enqueueing
5003
5004 uint n_workers = workers()->active_workers();
5005
5006 assert(rp->num_q() == n_workers, "sanity");
5007 assert(n_workers <= rp->max_num_q(), "sanity");
5008
5009 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5010 rp->enqueue_discovered_references(&par_task_executor);
5011 }
5012
5013 rp->verify_no_references_recorded();
5014 assert(!rp->discovery_enabled(), "should have been disabled");
5015
5016 // FIXME
5017 // CM's reference processing also cleans up the string and symbol tables.
5018 // Should we do that here also? We could, but it is a serial operation
5019 // and could significantly increase the pause time.
5020
5021 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5022 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5023 }
5024
5025 void G1CollectedHeap::pre_evacuate_collection_set() {
5026 _expand_heap_after_alloc_failure = true;
5027 _evacuation_failed = false;
5028
5029 // Disable the hot card cache.
5030 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5031 hot_card_cache->reset_hot_cache_claimed_index();
5032 hot_card_cache->set_use_cache(false);
5033
5034 }
5035
5036 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5037 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5038
5039 // Should G1EvacuationFailureALot be in effect for this GC?
5040 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5041
5042 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5043 double start_par_time_sec = os::elapsedTime();
5044 double end_par_time_sec;
5045
5046 {
5047 const uint n_workers = workers()->active_workers();
5048 G1RootProcessor root_processor(this, n_workers);
5049 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5050 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5051 if (collector_state()->during_initial_mark_pause()) {
5052 ClassLoaderDataGraph::clear_claimed_marks();
5053 }
5054
5055 print_termination_stats_hdr();
5056
5057 workers()->run_task(&g1_par_task);
5058 end_par_time_sec = os::elapsedTime();
5059
5060 // Closing the inner scope will execute the destructor
5061 // for the G1RootProcessor object. We record the current
5062 // elapsed time before closing the scope so that time
5063 // taken for the destructor is NOT included in the
5064 // reported parallel time.
5065 }
5066
5067 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5068
5069 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5070 phase_times->record_par_time(par_time_ms);
5071
5072 double code_root_fixup_time_ms =
5073 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5074 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5075
5076 // Process any discovered reference objects - we have
5077 // to do this _before_ we retire the GC alloc regions
5078 // as we may have to copy some 'reachable' referent
5079 // objects (and their reachable sub-graphs) that were
5080 // not copied during the pause.
5081 process_discovered_references(per_thread_states);
5082
5083 if (G1StringDedup::is_enabled()) {
5084 double fixup_start = os::elapsedTime();
5085
5086 G1STWIsAliveClosure is_alive(this);
5087 G1KeepAliveClosure keep_alive(this);
5088 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5089
5090 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5091 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5092 }
5093
5094 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5095
5096 if (evacuation_failed()) {
5097 remove_self_forwarding_pointers();
5098
5099 // Reset the G1EvacuationFailureALot counters and flags
5100 // Note: the values are reset only when an actual
5101 // evacuation failure occurs.
5102 NOT_PRODUCT(reset_evacuation_should_fail();)
5103 }
5104
5105 // Enqueue any remaining references remaining on the STW
5106 // reference processor's discovered lists. We need to do
5107 // this after the card table is cleaned (and verified) as
5108 // the act of enqueueing entries on to the pending list
5109 // will log these updates (and dirty their associated
5110 // cards). We need these updates logged to update any
5111 // RSets.
5112 enqueue_discovered_references(per_thread_states);
5113 }
5114
5115 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5116 _allocator->release_gc_alloc_regions(evacuation_info);
5117
5118 per_thread_states->flush();
5119
5120 record_obj_copy_mem_stats();
5121
5122 _survivor_evac_stats.adjust_desired_plab_sz();
5123 _old_evac_stats.adjust_desired_plab_sz();
5124
5125 // Reset and re-enable the hot card cache.
5126 // Note the counts for the cards in the regions in the
5127 // collection set are reset when the collection set is freed.
5128 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5129 hot_card_cache->reset_hot_cache();
5130 hot_card_cache->set_use_cache(true);
5131
5132 purge_code_root_memory();
5133
5134 redirty_logged_cards();
5135 #if defined(COMPILER2) || INCLUDE_JVMCI
5136 DerivedPointerTable::update_pointers();
5137 #endif
5138 }
5139
5140 void G1CollectedHeap::record_obj_copy_mem_stats() {
5141 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5142 create_g1_evac_summary(&_old_evac_stats));
5143 }
5144
5145 void G1CollectedHeap::free_region(HeapRegion* hr,
5146 FreeRegionList* free_list,
5147 bool par,
5148 bool locked) {
5149 assert(!hr->is_free(), "the region should not be free");
5150 assert(!hr->is_empty(), "the region should not be empty");
5151 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5152 assert(free_list != NULL, "pre-condition");
5153
5154 if (G1VerifyBitmaps) {
5155 MemRegion mr(hr->bottom(), hr->end());
5156 concurrent_mark()->clearRangePrevBitmap(mr);
5157 }
5158
5159 // Clear the card counts for this region.
5160 // Note: we only need to do this if the region is not young
5161 // (since we don't refine cards in young regions).
5162 if (!hr->is_young()) {
5163 _cg1r->hot_card_cache()->reset_card_counts(hr);
5164 }
5165 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5166 free_list->add_ordered(hr);
5167 }
5168
5169 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5170 FreeRegionList* free_list,
5171 bool par) {
5172 assert(hr->is_humongous(), "this is only for humongous regions");
5173 assert(free_list != NULL, "pre-condition");
5174 hr->clear_humongous();
5175 free_region(hr, free_list, par);
5176 }
5177
5178 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5179 const HeapRegionSetCount& humongous_regions_removed) {
5180 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5181 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5182 _old_set.bulk_remove(old_regions_removed);
5183 _humongous_set.bulk_remove(humongous_regions_removed);
5184 }
5185
5186 }
5187
5188 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5189 assert(list != NULL, "list can't be null");
5190 if (!list->is_empty()) {
5191 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5192 _hrm.insert_list_into_free_list(list);
5193 }
5194 }
5195
5196 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5197 decrease_used(bytes);
5198 }
5199
5200 class G1ParCleanupCTTask : public AbstractGangTask {
5201 G1SATBCardTableModRefBS* _ct_bs;
5202 G1CollectedHeap* _g1h;
5203 HeapRegion* volatile _su_head;
5204 public:
5205 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5206 G1CollectedHeap* g1h) :
5207 AbstractGangTask("G1 Par Cleanup CT Task"),
5208 _ct_bs(ct_bs), _g1h(g1h) { }
5209
5210 void work(uint worker_id) {
5211 HeapRegion* r;
5212 while (r = _g1h->pop_dirty_cards_region()) {
5213 clear_cards(r);
5214 }
5215 }
5216
5217 void clear_cards(HeapRegion* r) {
5218 // Cards of the survivors should have already been dirtied.
5219 if (!r->is_survivor()) {
5220 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5221 }
5222 }
5223 };
5224
5225 #ifndef PRODUCT
5226 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5227 G1CollectedHeap* _g1h;
5228 G1SATBCardTableModRefBS* _ct_bs;
5229 public:
5230 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5231 : _g1h(g1h), _ct_bs(ct_bs) { }
5232 virtual bool doHeapRegion(HeapRegion* r) {
5233 if (r->is_survivor()) {
5234 _g1h->verify_dirty_region(r);
5235 } else {
5236 _g1h->verify_not_dirty_region(r);
5237 }
5238 return false;
5239 }
5240 };
5241
5242 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5243 // All of the region should be clean.
5244 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5245 MemRegion mr(hr->bottom(), hr->end());
5246 ct_bs->verify_not_dirty_region(mr);
5247 }
5248
5249 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5250 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5251 // dirty allocated blocks as they allocate them. The thread that
5252 // retires each region and replaces it with a new one will do a
5253 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5254 // not dirty that area (one less thing to have to do while holding
5255 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5256 // is dirty.
5257 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5258 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5259 if (hr->is_young()) {
5260 ct_bs->verify_g1_young_region(mr);
5261 } else {
5262 ct_bs->verify_dirty_region(mr);
5263 }
5264 }
5265
5266 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5267 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5268 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5269 verify_dirty_region(hr);
5270 }
5271 }
5272
5273 void G1CollectedHeap::verify_dirty_young_regions() {
5274 verify_dirty_young_list(_young_list->first_region());
5275 }
5276
5277 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5278 HeapWord* tams, HeapWord* end) {
5279 guarantee(tams <= end,
5280 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5281 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5282 if (result < end) {
5283 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5284 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5285 return false;
5286 }
5287 return true;
5288 }
5289
5290 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5291 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5292 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5293
5294 HeapWord* bottom = hr->bottom();
5295 HeapWord* ptams = hr->prev_top_at_mark_start();
5296 HeapWord* ntams = hr->next_top_at_mark_start();
5297 HeapWord* end = hr->end();
5298
5299 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5300
5301 bool res_n = true;
5302 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5303 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5304 // if we happen to be in that state.
5305 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5306 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5307 }
5308 if (!res_p || !res_n) {
5309 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5310 log_info(gc, verify)("#### Caller: %s", caller);
5311 return false;
5312 }
5313 return true;
5314 }
5315
5316 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5317 if (!G1VerifyBitmaps) return;
5318
5319 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5320 }
5321
5322 class G1VerifyBitmapClosure : public HeapRegionClosure {
5323 private:
5324 const char* _caller;
5325 G1CollectedHeap* _g1h;
5326 bool _failures;
5327
5328 public:
5329 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5330 _caller(caller), _g1h(g1h), _failures(false) { }
5331
5332 bool failures() { return _failures; }
5333
5334 virtual bool doHeapRegion(HeapRegion* hr) {
5335 bool result = _g1h->verify_bitmaps(_caller, hr);
5336 if (!result) {
5337 _failures = true;
5338 }
5339 return false;
5340 }
5341 };
5342
5343 void G1CollectedHeap::check_bitmaps(const char* caller) {
5344 if (!G1VerifyBitmaps) return;
5345
5346 G1VerifyBitmapClosure cl(caller, this);
5347 heap_region_iterate(&cl);
5348 guarantee(!cl.failures(), "bitmap verification");
5349 }
5350
5351 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5352 private:
5353 bool _failures;
5354 public:
5355 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5356
5357 virtual bool doHeapRegion(HeapRegion* hr) {
5358 uint i = hr->hrm_index();
5359 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5360 if (hr->is_humongous()) {
5361 if (hr->in_collection_set()) {
5362 log_info(gc, verify)("\n## humongous region %u in CSet", i);
5363 _failures = true;
5364 return true;
5365 }
5366 if (cset_state.is_in_cset()) {
5367 log_info(gc, verify)("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5368 _failures = true;
5369 return true;
5370 }
5371 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5372 log_info(gc, verify)("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5373 _failures = true;
5374 return true;
5375 }
5376 } else {
5377 if (cset_state.is_humongous()) {
5378 log_info(gc, verify)("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5379 _failures = true;
5380 return true;
5381 }
5382 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5383 log_info(gc, verify)("\n## in CSet %d / cset state %d inconsistency for region %u",
5384 hr->in_collection_set(), cset_state.value(), i);
5385 _failures = true;
5386 return true;
5387 }
5388 if (cset_state.is_in_cset()) {
5389 if (hr->is_young() != (cset_state.is_young())) {
5390 log_info(gc, verify)("\n## is_young %d / cset state %d inconsistency for region %u",
5391 hr->is_young(), cset_state.value(), i);
5392 _failures = true;
5393 return true;
5394 }
5395 if (hr->is_old() != (cset_state.is_old())) {
5396 log_info(gc, verify)("\n## is_old %d / cset state %d inconsistency for region %u",
5397 hr->is_old(), cset_state.value(), i);
5398 _failures = true;
5399 return true;
5400 }
5401 }
5402 }
5403 return false;
5404 }
5405
5406 bool failures() const { return _failures; }
5407 };
5408
5409 bool G1CollectedHeap::check_cset_fast_test() {
5410 G1CheckCSetFastTableClosure cl;
5411 _hrm.iterate(&cl);
5412 return !cl.failures();
5413 }
5414 #endif // PRODUCT
5415
5416 void G1CollectedHeap::cleanUpCardTable() {
5417 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5418 double start = os::elapsedTime();
5419
5420 {
5421 // Iterate over the dirty cards region list.
5422 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5423
5424 workers()->run_task(&cleanup_task);
5425 #ifndef PRODUCT
5426 if (G1VerifyCTCleanup || VerifyAfterGC) {
5427 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5428 heap_region_iterate(&cleanup_verifier);
5429 }
5430 #endif
5431 }
5432
5433 double elapsed = os::elapsedTime() - start;
5434 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5435 }
5436
5437 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5438 size_t pre_used = 0;
5439 FreeRegionList local_free_list("Local List for CSet Freeing");
5440
5441 double young_time_ms = 0.0;
5442 double non_young_time_ms = 0.0;
5443
5444 // Since the collection set is a superset of the the young list,
5445 // all we need to do to clear the young list is clear its
5446 // head and length, and unlink any young regions in the code below
5447 _young_list->clear();
5448
5449 G1CollectorPolicy* policy = g1_policy();
5450
5451 double start_sec = os::elapsedTime();
5452 bool non_young = true;
5453
5454 HeapRegion* cur = cs_head;
5455 int age_bound = -1;
5456 size_t rs_lengths = 0;
5457
5458 while (cur != NULL) {
5459 assert(!is_on_master_free_list(cur), "sanity");
5460 if (non_young) {
5461 if (cur->is_young()) {
5462 double end_sec = os::elapsedTime();
5463 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5464 non_young_time_ms += elapsed_ms;
5465
5466 start_sec = os::elapsedTime();
5467 non_young = false;
5468 }
5469 } else {
5470 if (!cur->is_young()) {
5471 double end_sec = os::elapsedTime();
5472 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5473 young_time_ms += elapsed_ms;
5474
5475 start_sec = os::elapsedTime();
5476 non_young = true;
5477 }
5478 }
5479
5480 rs_lengths += cur->rem_set()->occupied_locked();
5481
5482 HeapRegion* next = cur->next_in_collection_set();
5483 assert(cur->in_collection_set(), "bad CS");
5484 cur->set_next_in_collection_set(NULL);
5485 clear_in_cset(cur);
5486
5487 if (cur->is_young()) {
5488 int index = cur->young_index_in_cset();
5489 assert(index != -1, "invariant");
5490 assert((uint) index < policy->young_cset_region_length(), "invariant");
5491 size_t words_survived = surviving_young_words[index];
5492 cur->record_surv_words_in_group(words_survived);
5493
5494 // At this point the we have 'popped' cur from the collection set
5495 // (linked via next_in_collection_set()) but it is still in the
5496 // young list (linked via next_young_region()). Clear the
5497 // _next_young_region field.
5498 cur->set_next_young_region(NULL);
5499 } else {
5500 int index = cur->young_index_in_cset();
5501 assert(index == -1, "invariant");
5502 }
5503
5504 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5505 (!cur->is_young() && cur->young_index_in_cset() == -1),
5506 "invariant" );
5507
5508 if (!cur->evacuation_failed()) {
5509 MemRegion used_mr = cur->used_region();
5510
5511 // And the region is empty.
5512 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5513 pre_used += cur->used();
5514 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5515 } else {
5516 cur->uninstall_surv_rate_group();
5517 if (cur->is_young()) {
5518 cur->set_young_index_in_cset(-1);
5519 }
5520 cur->set_evacuation_failed(false);
5521 // The region is now considered to be old.
5522 cur->set_old();
5523 // Do some allocation statistics accounting. Regions that failed evacuation
5524 // are always made old, so there is no need to update anything in the young
5525 // gen statistics, but we need to update old gen statistics.
5526 size_t used_words = cur->marked_bytes() / HeapWordSize;
5527 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5528 _old_set.add(cur);
5529 evacuation_info.increment_collectionset_used_after(cur->used());
5530 }
5531 cur = next;
5532 }
5533
5534 evacuation_info.set_regions_freed(local_free_list.length());
5535 policy->record_max_rs_lengths(rs_lengths);
5536 policy->cset_regions_freed();
5537
5538 double end_sec = os::elapsedTime();
5539 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5540
5541 if (non_young) {
5542 non_young_time_ms += elapsed_ms;
5543 } else {
5544 young_time_ms += elapsed_ms;
5545 }
5546
5547 prepend_to_freelist(&local_free_list);
5548 decrement_summary_bytes(pre_used);
5549 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5550 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5551 }
5552
5553 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5554 private:
5555 FreeRegionList* _free_region_list;
5556 HeapRegionSet* _proxy_set;
5557 HeapRegionSetCount _humongous_regions_removed;
5558 size_t _freed_bytes;
5559 public:
5560
5561 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5562 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5563 }
5564
5565 virtual bool doHeapRegion(HeapRegion* r) {
5566 if (!r->is_starts_humongous()) {
5567 return false;
5568 }
5569
5570 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5571
5572 oop obj = (oop)r->bottom();
5573 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5574
5575 // The following checks whether the humongous object is live are sufficient.
5576 // The main additional check (in addition to having a reference from the roots
5577 // or the young gen) is whether the humongous object has a remembered set entry.
5578 //
5579 // A humongous object cannot be live if there is no remembered set for it
5580 // because:
5581 // - there can be no references from within humongous starts regions referencing
5582 // the object because we never allocate other objects into them.
5583 // (I.e. there are no intra-region references that may be missed by the
5584 // remembered set)
5585 // - as soon there is a remembered set entry to the humongous starts region
5586 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5587 // until the end of a concurrent mark.
5588 //
5589 // It is not required to check whether the object has been found dead by marking
5590 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5591 // all objects allocated during that time are considered live.
5592 // SATB marking is even more conservative than the remembered set.
5593 // So if at this point in the collection there is no remembered set entry,
5594 // nobody has a reference to it.
5595 // At the start of collection we flush all refinement logs, and remembered sets
5596 // are completely up-to-date wrt to references to the humongous object.
5597 //
5598 // Other implementation considerations:
5599 // - never consider object arrays at this time because they would pose
5600 // considerable effort for cleaning up the the remembered sets. This is
5601 // required because stale remembered sets might reference locations that
5602 // are currently allocated into.
5603 uint region_idx = r->hrm_index();
5604 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5605 !r->rem_set()->is_empty()) {
5606 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
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 return false;
5617 }
5618
5619 guarantee(obj->is_typeArray(),
5620 "Only eagerly reclaiming type arrays is supported, but the object "
5621 PTR_FORMAT " is not.", p2i(r->bottom()));
5622
5623 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5624 region_idx,
5625 (size_t)obj->size() * HeapWordSize,
5626 p2i(r->bottom()),
5627 r->rem_set()->occupied(),
5628 r->rem_set()->strong_code_roots_list_length(),
5629 next_bitmap->isMarked(r->bottom()),
5630 g1h->is_humongous_reclaim_candidate(region_idx),
5631 obj->is_typeArray()
5632 );
5633
5634 // Need to clear mark bit of the humongous object if already set.
5635 if (next_bitmap->isMarked(r->bottom())) {
5636 next_bitmap->clear(r->bottom());
5637 }
5638 do {
5639 HeapRegion* next = g1h->next_region_in_humongous(r);
5640 _freed_bytes += r->used();
5641 r->set_containing_set(NULL);
5642 _humongous_regions_removed.increment(1u, r->capacity());
5643 g1h->free_humongous_region(r, _free_region_list, false);
5644 r = next;
5645 } while (r != NULL);
5646
5647 return false;
5648 }
5649
5650 HeapRegionSetCount& humongous_free_count() {
5651 return _humongous_regions_removed;
5652 }
5653
5654 size_t bytes_freed() const {
5655 return _freed_bytes;
5656 }
5657
5658 size_t humongous_reclaimed() const {
5659 return _humongous_regions_removed.length();
5660 }
5661 };
5662
5663 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5664 assert_at_safepoint(true);
5665
5666 if (!G1EagerReclaimHumongousObjects ||
5667 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5668 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5669 return;
5670 }
5671
5672 double start_time = os::elapsedTime();
5673
5674 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5675
5676 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5677 heap_region_iterate(&cl);
5678
5679 HeapRegionSetCount empty_set;
5680 remove_from_old_sets(empty_set, cl.humongous_free_count());
5681
5682 G1HRPrinter* hrp = hr_printer();
5683 if (hrp->is_active()) {
5684 FreeRegionListIterator iter(&local_cleanup_list);
5685 while (iter.more_available()) {
5686 HeapRegion* hr = iter.get_next();
5687 hrp->cleanup(hr);
5688 }
5689 }
5690
5691 prepend_to_freelist(&local_cleanup_list);
5692 decrement_summary_bytes(cl.bytes_freed());
5693
5694 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5695 cl.humongous_reclaimed());
5696 }
5697
5698 // This routine is similar to the above but does not record
5699 // any policy statistics or update free lists; we are abandoning
5700 // the current incremental collection set in preparation of a
5701 // full collection. After the full GC we will start to build up
5702 // the incremental collection set again.
5703 // This is only called when we're doing a full collection
5704 // and is immediately followed by the tearing down of the young list.
5705
5706 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5707 HeapRegion* cur = cs_head;
5708
5709 while (cur != NULL) {
5710 HeapRegion* next = cur->next_in_collection_set();
5711 assert(cur->in_collection_set(), "bad CS");
5712 cur->set_next_in_collection_set(NULL);
5713 clear_in_cset(cur);
5714 cur->set_young_index_in_cset(-1);
5715 cur = next;
5716 }
5717 }
5718
5719 void G1CollectedHeap::set_free_regions_coming() {
5720 log_develop(gc, freelist)("G1ConcRegionFreeing [cm thread] : "
5721 "setting free regions coming");
5722
5723 assert(!free_regions_coming(), "pre-condition");
5724 _free_regions_coming = true;
5725 }
5726
5727 void G1CollectedHeap::reset_free_regions_coming() {
5728 assert(free_regions_coming(), "pre-condition");
5729
5730 {
5731 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5732 _free_regions_coming = false;
5733 SecondaryFreeList_lock->notify_all();
5734 }
5735
5736 log_develop(gc, freelist)("G1ConcRegionFreeing [cm thread] : "
5737 "reset free regions coming");
5738 }
5739
5740 void G1CollectedHeap::wait_while_free_regions_coming() {
5741 // Most of the time we won't have to wait, so let's do a quick test
5742 // first before we take the lock.
5743 if (!free_regions_coming()) {
5744 return;
5745 }
5746
5747 log_develop(gc, freelist)("G1ConcRegionFreeing [other] : "
5748 "waiting for free regions");
5749
5750 {
5751 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5752 while (free_regions_coming()) {
5753 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5754 }
5755 }
5756
5757 log_develop(gc, freelist)("G1ConcRegionFreeing [other] : "
5758 "done waiting for free regions");
5759 }
5760
5761 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5762 return _allocator->is_retained_old_region(hr);
5763 }
5764
5765 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5766 _young_list->push_region(hr);
5767 }
5768
5769 class NoYoungRegionsClosure: public HeapRegionClosure {
5770 private:
5771 bool _success;
5772 public:
5773 NoYoungRegionsClosure() : _success(true) { }
5774 bool doHeapRegion(HeapRegion* r) {
5775 if (r->is_young()) {
5776 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5777 p2i(r->bottom()), p2i(r->end()));
5778 _success = false;
5779 }
5780 return false;
5781 }
5782 bool success() { return _success; }
5783 };
5784
5785 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5786 bool ret = _young_list->check_list_empty(check_sample);
5787
5788 if (check_heap) {
5789 NoYoungRegionsClosure closure;
5790 heap_region_iterate(&closure);
5791 ret = ret && closure.success();
5792 }
5793
5794 return ret;
5795 }
5796
5797 class TearDownRegionSetsClosure : public HeapRegionClosure {
5798 private:
5799 HeapRegionSet *_old_set;
5800
5801 public:
5802 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5803
5804 bool doHeapRegion(HeapRegion* r) {
5805 if (r->is_old()) {
5806 _old_set->remove(r);
5807 } else {
5808 // We ignore free regions, we'll empty the free list afterwards.
5809 // We ignore young regions, we'll empty the young list afterwards.
5810 // We ignore humongous regions, we're not tearing down the
5811 // humongous regions set.
5812 assert(r->is_free() || r->is_young() || r->is_humongous(),
5813 "it cannot be another type");
5814 }
5815 return false;
5816 }
5817
5818 ~TearDownRegionSetsClosure() {
5819 assert(_old_set->is_empty(), "post-condition");
5820 }
5821 };
5822
5823 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5824 assert_at_safepoint(true /* should_be_vm_thread */);
5825
5826 if (!free_list_only) {
5827 TearDownRegionSetsClosure cl(&_old_set);
5828 heap_region_iterate(&cl);
5829
5830 // Note that emptying the _young_list is postponed and instead done as
5831 // the first step when rebuilding the regions sets again. The reason for
5832 // this is that during a full GC string deduplication needs to know if
5833 // a collected region was young or old when the full GC was initiated.
5834 }
5835 _hrm.remove_all_free_regions();
5836 }
5837
5838 void G1CollectedHeap::increase_used(size_t bytes) {
5839 _summary_bytes_used += bytes;
5840 }
5841
5842 void G1CollectedHeap::decrease_used(size_t bytes) {
5843 assert(_summary_bytes_used >= bytes,
5844 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5845 _summary_bytes_used, bytes);
5846 _summary_bytes_used -= bytes;
5847 }
5848
5849 void G1CollectedHeap::set_used(size_t bytes) {
5850 _summary_bytes_used = bytes;
5851 }
5852
5853 class RebuildRegionSetsClosure : public HeapRegionClosure {
5854 private:
5855 bool _free_list_only;
5856 HeapRegionSet* _old_set;
5857 HeapRegionManager* _hrm;
5858 size_t _total_used;
5859
5860 public:
5861 RebuildRegionSetsClosure(bool free_list_only,
5862 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5863 _free_list_only(free_list_only),
5864 _old_set(old_set), _hrm(hrm), _total_used(0) {
5865 assert(_hrm->num_free_regions() == 0, "pre-condition");
5866 if (!free_list_only) {
5867 assert(_old_set->is_empty(), "pre-condition");
5868 }
5869 }
5870
5871 bool doHeapRegion(HeapRegion* r) {
5872 if (r->is_empty()) {
5873 // Add free regions to the free list
5874 r->set_free();
5875 r->set_allocation_context(AllocationContext::system());
5876 _hrm->insert_into_free_list(r);
5877 } else if (!_free_list_only) {
5878 assert(!r->is_young(), "we should not come across young regions");
5879
5880 if (r->is_humongous()) {
5881 // We ignore humongous regions. We left the humongous set unchanged.
5882 } else {
5883 // Objects that were compacted would have ended up on regions
5884 // that were previously old or free. Archive regions (which are
5885 // old) will not have been touched.
5886 assert(r->is_free() || r->is_old(), "invariant");
5887 // We now consider them old, so register as such. Leave
5888 // archive regions set that way, however, while still adding
5889 // them to the old set.
5890 if (!r->is_archive()) {
5891 r->set_old();
5892 }
5893 _old_set->add(r);
5894 }
5895 _total_used += r->used();
5896 }
5897
5898 return false;
5899 }
5900
5901 size_t total_used() {
5902 return _total_used;
5903 }
5904 };
5905
5906 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5907 assert_at_safepoint(true /* should_be_vm_thread */);
5908
5909 if (!free_list_only) {
5910 _young_list->empty_list();
5911 }
5912
5913 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5914 heap_region_iterate(&cl);
5915
5916 if (!free_list_only) {
5917 set_used(cl.total_used());
5918 if (_archive_allocator != NULL) {
5919 _archive_allocator->clear_used();
5920 }
5921 }
5922 assert(used_unlocked() == recalculate_used(),
5923 "inconsistent used_unlocked(), "
5924 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5925 used_unlocked(), recalculate_used());
5926 }
5927
5928 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5929 _refine_cte_cl->set_concurrent(concurrent);
5930 }
5931
5932 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5933 HeapRegion* hr = heap_region_containing(p);
5934 return hr->is_in(p);
5935 }
5936
5937 // Methods for the mutator alloc region
5938
5939 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5940 bool force) {
5941 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5942 assert(!force || g1_policy()->can_expand_young_list(),
5943 "if force is true we should be able to expand the young list");
5944 bool young_list_full = g1_policy()->is_young_list_full();
5945 if (force || !young_list_full) {
5946 HeapRegion* new_alloc_region = new_region(word_size,
5947 false /* is_old */,
5948 false /* do_expand */);
5949 if (new_alloc_region != NULL) {
5950 set_region_short_lived_locked(new_alloc_region);
5951 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5952 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5953 return new_alloc_region;
5954 }
5955 }
5956 return NULL;
5957 }
5958
5959 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5960 size_t allocated_bytes) {
5961 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5962 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5963
5964 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5965 increase_used(allocated_bytes);
5966 _hr_printer.retire(alloc_region);
5967 // We update the eden sizes here, when the region is retired,
5968 // instead of when it's allocated, since this is the point that its
5969 // used space has been recored in _summary_bytes_used.
5970 g1mm()->update_eden_size();
5971 }
5972
5973 // Methods for the GC alloc regions
5974
5975 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5976 uint count,
5977 InCSetState dest) {
5978 assert(FreeList_lock->owned_by_self(), "pre-condition");
5979
5980 if (count < g1_policy()->max_regions(dest)) {
5981 const bool is_survivor = (dest.is_young());
5982 HeapRegion* new_alloc_region = new_region(word_size,
5983 !is_survivor,
5984 true /* do_expand */);
5985 if (new_alloc_region != NULL) {
5986 // We really only need to do this for old regions given that we
5987 // should never scan survivors. But it doesn't hurt to do it
5988 // for survivors too.
5989 new_alloc_region->record_timestamp();
5990 if (is_survivor) {
5991 new_alloc_region->set_survivor();
5992 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
5993 check_bitmaps("Survivor Region Allocation", new_alloc_region);
5994 } else {
5995 new_alloc_region->set_old();
5996 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
5997 check_bitmaps("Old Region Allocation", new_alloc_region);
5998 }
5999 bool during_im = collector_state()->during_initial_mark_pause();
6000 new_alloc_region->note_start_of_copying(during_im);
6001 return new_alloc_region;
6002 }
6003 }
6004 return NULL;
6005 }
6006
6007 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6008 size_t allocated_bytes,
6009 InCSetState dest) {
6010 bool during_im = collector_state()->during_initial_mark_pause();
6011 alloc_region->note_end_of_copying(during_im);
6012 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6013 if (dest.is_young()) {
6014 young_list()->add_survivor_region(alloc_region);
6015 } else {
6016 _old_set.add(alloc_region);
6017 }
6018 _hr_printer.retire(alloc_region);
6019 }
6020
6021 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6022 bool expanded = false;
6023 uint index = _hrm.find_highest_free(&expanded);
6024
6025 if (index != G1_NO_HRM_INDEX) {
6026 if (expanded) {
6027 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6028 HeapRegion::GrainWords * HeapWordSize);
6029 }
6030 _hrm.allocate_free_regions_starting_at(index, 1);
6031 return region_at(index);
6032 }
6033 return NULL;
6034 }
6035
6036 // Heap region set verification
6037
6038 class VerifyRegionListsClosure : public HeapRegionClosure {
6039 private:
6040 HeapRegionSet* _old_set;
6041 HeapRegionSet* _humongous_set;
6042 HeapRegionManager* _hrm;
6043
6044 public:
6045 HeapRegionSetCount _old_count;
6046 HeapRegionSetCount _humongous_count;
6047 HeapRegionSetCount _free_count;
6048
6049 VerifyRegionListsClosure(HeapRegionSet* old_set,
6050 HeapRegionSet* humongous_set,
6051 HeapRegionManager* hrm) :
6052 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6053 _old_count(), _humongous_count(), _free_count(){ }
6054
6055 bool doHeapRegion(HeapRegion* hr) {
6056 if (hr->is_young()) {
6057 // TODO
6058 } else if (hr->is_humongous()) {
6059 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6060 _humongous_count.increment(1u, hr->capacity());
6061 } else if (hr->is_empty()) {
6062 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6063 _free_count.increment(1u, hr->capacity());
6064 } else if (hr->is_old()) {
6065 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6066 _old_count.increment(1u, hr->capacity());
6067 } else {
6068 // There are no other valid region types. Check for one invalid
6069 // one we can identify: pinned without old or humongous set.
6070 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6071 ShouldNotReachHere();
6072 }
6073 return false;
6074 }
6075
6076 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6077 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6078 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6079 old_set->total_capacity_bytes(), _old_count.capacity());
6080
6081 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6082 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6083 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6084
6085 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());
6086 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6087 free_list->total_capacity_bytes(), _free_count.capacity());
6088 }
6089 };
6090
6091 void G1CollectedHeap::verify_region_sets() {
6092 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6093
6094 // First, check the explicit lists.
6095 _hrm.verify();
6096 {
6097 // Given that a concurrent operation might be adding regions to
6098 // the secondary free list we have to take the lock before
6099 // verifying it.
6100 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6101 _secondary_free_list.verify_list();
6102 }
6103
6104 // If a concurrent region freeing operation is in progress it will
6105 // be difficult to correctly attributed any free regions we come
6106 // across to the correct free list given that they might belong to
6107 // one of several (free_list, secondary_free_list, any local lists,
6108 // etc.). So, if that's the case we will skip the rest of the
6109 // verification operation. Alternatively, waiting for the concurrent
6110 // operation to complete will have a non-trivial effect on the GC's
6111 // operation (no concurrent operation will last longer than the
6112 // interval between two calls to verification) and it might hide
6113 // any issues that we would like to catch during testing.
6114 if (free_regions_coming()) {
6115 return;
6116 }
6117
6118 // Make sure we append the secondary_free_list on the free_list so
6119 // that all free regions we will come across can be safely
6120 // attributed to the free_list.
6121 append_secondary_free_list_if_not_empty_with_lock();
6122
6123 // Finally, make sure that the region accounting in the lists is
6124 // consistent with what we see in the heap.
6125
6126 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6127 heap_region_iterate(&cl);
6128 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6129 }
6130
6131 // Optimized nmethod scanning
6132
6133 class RegisterNMethodOopClosure: public OopClosure {
6134 G1CollectedHeap* _g1h;
6135 nmethod* _nm;
6136
6137 template <class T> void do_oop_work(T* p) {
6138 T heap_oop = oopDesc::load_heap_oop(p);
6139 if (!oopDesc::is_null(heap_oop)) {
6140 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6141 HeapRegion* hr = _g1h->heap_region_containing(obj);
6142 assert(!hr->is_continues_humongous(),
6143 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6144 " starting at " HR_FORMAT,
6145 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6146
6147 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6148 hr->add_strong_code_root_locked(_nm);
6149 }
6150 }
6151
6152 public:
6153 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6154 _g1h(g1h), _nm(nm) {}
6155
6156 void do_oop(oop* p) { do_oop_work(p); }
6157 void do_oop(narrowOop* p) { do_oop_work(p); }
6158 };
6159
6160 class UnregisterNMethodOopClosure: public OopClosure {
6161 G1CollectedHeap* _g1h;
6162 nmethod* _nm;
6163
6164 template <class T> void do_oop_work(T* p) {
6165 T heap_oop = oopDesc::load_heap_oop(p);
6166 if (!oopDesc::is_null(heap_oop)) {
6167 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6168 HeapRegion* hr = _g1h->heap_region_containing(obj);
6169 assert(!hr->is_continues_humongous(),
6170 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6171 " starting at " HR_FORMAT,
6172 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6173
6174 hr->remove_strong_code_root(_nm);
6175 }
6176 }
6177
6178 public:
6179 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6180 _g1h(g1h), _nm(nm) {}
6181
6182 void do_oop(oop* p) { do_oop_work(p); }
6183 void do_oop(narrowOop* p) { do_oop_work(p); }
6184 };
6185
6186 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6187 CollectedHeap::register_nmethod(nm);
6188
6189 guarantee(nm != NULL, "sanity");
6190 RegisterNMethodOopClosure reg_cl(this, nm);
6191 nm->oops_do(®_cl);
6192 }
6193
6194 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6195 CollectedHeap::unregister_nmethod(nm);
6196
6197 guarantee(nm != NULL, "sanity");
6198 UnregisterNMethodOopClosure reg_cl(this, nm);
6199 nm->oops_do(®_cl, true);
6200 }
6201
6202 void G1CollectedHeap::purge_code_root_memory() {
6203 double purge_start = os::elapsedTime();
6204 G1CodeRootSet::purge();
6205 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6206 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6207 }
6208
6209 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6210 G1CollectedHeap* _g1h;
6211
6212 public:
6213 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6214 _g1h(g1h) {}
6215
6216 void do_code_blob(CodeBlob* cb) {
6217 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6218 if (nm == NULL) {
6219 return;
6220 }
6221
6222 if (ScavengeRootsInCode) {
6223 _g1h->register_nmethod(nm);
6224 }
6225 }
6226 };
6227
6228 void G1CollectedHeap::rebuild_strong_code_roots() {
6229 RebuildStrongCodeRootClosure blob_cl(this);
6230 CodeCache::blobs_do(&blob_cl);
6231 }