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/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1Log.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_processed;
117
118 public:
119 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 *card_ptr = CardTableModRefBS::dirty_card_val();
123 _num_processed++;
124 return true;
125 }
126
127 size_t num_processed() const { return _num_processed; }
128 };
129
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
142 {
143 // Claim the right to put the region on the dirty cards region list
144 // by installing a self pointer.
145 HeapRegion* next = hr->get_next_dirty_cards_region();
146 if (next == NULL) {
147 HeapRegion* res = (HeapRegion*)
148 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
149 NULL);
150 if (res == NULL) {
151 HeapRegion* head;
152 do {
153 // Put the region to the dirty cards region list.
154 head = _dirty_cards_region_list;
155 next = (HeapRegion*)
156 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
157 if (next == head) {
158 assert(hr->get_next_dirty_cards_region() == hr,
159 "hr->get_next_dirty_cards_region() != hr");
160 if (next == NULL) {
161 // The last region in the list points to itself.
162 hr->set_next_dirty_cards_region(hr);
163 } else {
164 hr->set_next_dirty_cards_region(next);
165 }
166 }
167 } while (next != head);
168 }
169 }
170 }
171
172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
173 {
174 HeapRegion* head;
175 HeapRegion* hr;
176 do {
177 head = _dirty_cards_region_list;
178 if (head == NULL) {
179 return NULL;
180 }
181 HeapRegion* new_head = head->get_next_dirty_cards_region();
182 if (head == new_head) {
183 // The last region.
184 new_head = NULL;
185 }
186 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
187 head);
188 } while (hr != head);
189 assert(hr != NULL, "invariant");
190 hr->set_next_dirty_cards_region(NULL);
191 return hr;
192 }
193
194 // Returns true if the reference points to an object that
195 // can move in an incremental collection.
196 bool G1CollectedHeap::is_scavengable(const void* p) {
197 HeapRegion* hr = heap_region_containing(p);
198 return !hr->is_pinned();
199 }
200
201 // Private methods.
202
203 HeapRegion*
204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
205 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
206 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
207 if (!_secondary_free_list.is_empty()) {
208 if (G1ConcRegionFreeingVerbose) {
209 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
210 "secondary_free_list has %u entries",
211 _secondary_free_list.length());
212 }
213 // It looks as if there are free regions available on the
214 // secondary_free_list. Let's move them to the free_list and try
215 // again to allocate from it.
216 append_secondary_free_list();
217
218 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
219 "empty we should have moved at least one entry to the free_list");
220 HeapRegion* res = _hrm.allocate_free_region(is_old);
221 if (G1ConcRegionFreeingVerbose) {
222 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
223 "allocated " HR_FORMAT " from secondary_free_list",
224 HR_FORMAT_PARAMS(res));
225 }
226 return res;
227 }
228
229 // Wait here until we get notified either when (a) there are no
230 // more free regions coming or (b) some regions have been moved on
231 // the secondary_free_list.
232 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
233 }
234
235 if (G1ConcRegionFreeingVerbose) {
236 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
237 "could not allocate from secondary_free_list");
238 }
239 return NULL;
240 }
241
242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
243 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
244 "the only time we use this to allocate a humongous region is "
245 "when we are allocating a single humongous region");
246
247 HeapRegion* res;
248 if (G1StressConcRegionFreeing) {
249 if (!_secondary_free_list.is_empty()) {
250 if (G1ConcRegionFreeingVerbose) {
251 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
252 "forced to look at the secondary_free_list");
253 }
254 res = new_region_try_secondary_free_list(is_old);
255 if (res != NULL) {
256 return res;
257 }
258 }
259 }
260
261 res = _hrm.allocate_free_region(is_old);
262
263 if (res == NULL) {
264 if (G1ConcRegionFreeingVerbose) {
265 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
266 "res == NULL, trying the secondary_free_list");
267 }
268 res = new_region_try_secondary_free_list(is_old);
269 }
270 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
271 // Currently, only attempts to allocate GC alloc regions set
272 // do_expand to true. So, we should only reach here during a
273 // safepoint. If this assumption changes we might have to
274 // reconsider the use of _expand_heap_after_alloc_failure.
275 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
276
277 ergo_verbose1(ErgoHeapSizing,
278 "attempt heap expansion",
279 ergo_format_reason("region allocation request failed")
280 ergo_format_byte("allocation request"),
281 word_size * HeapWordSize);
282 if (expand(word_size * HeapWordSize)) {
283 // Given that expand() succeeded in expanding the heap, and we
284 // always expand the heap by an amount aligned to the heap
285 // region size, the free list should in theory not be empty.
286 // In either case allocate_free_region() will check for NULL.
287 res = _hrm.allocate_free_region(is_old);
288 } else {
289 _expand_heap_after_alloc_failure = false;
290 }
291 }
292 return res;
293 }
294
295 HeapWord*
296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
297 uint num_regions,
298 size_t word_size,
299 AllocationContext_t context) {
300 assert(first != G1_NO_HRM_INDEX, "pre-condition");
301 assert(is_humongous(word_size), "word_size should be humongous");
302 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
303
304 // Index of last region in the series + 1.
305 uint last = first + num_regions;
306
307 // We need to initialize the region(s) we just discovered. This is
308 // a bit tricky given that it can happen concurrently with
309 // refinement threads refining cards on these regions and
310 // potentially wanting to refine the BOT as they are scanning
311 // those cards (this can happen shortly after a cleanup; see CR
312 // 6991377). So we have to set up the region(s) carefully and in
313 // a specific order.
314
315 // The word size sum of all the regions we will allocate.
316 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
317 assert(word_size <= word_size_sum, "sanity");
318
319 // This will be the "starts humongous" region.
320 HeapRegion* first_hr = region_at(first);
321 // The header of the new object will be placed at the bottom of
322 // the first region.
323 HeapWord* new_obj = first_hr->bottom();
324 // This will be the new top of the new object.
325 HeapWord* obj_top = new_obj + word_size;
326
327 // First, we need to zero the header of the space that we will be
328 // allocating. When we update top further down, some refinement
329 // threads might try to scan the region. By zeroing the header we
330 // ensure that any thread that will try to scan the region will
331 // come across the zero klass word and bail out.
332 //
333 // NOTE: It would not have been correct to have used
334 // CollectedHeap::fill_with_object() and make the space look like
335 // an int array. The thread that is doing the allocation will
336 // later update the object header to a potentially different array
337 // type and, for a very short period of time, the klass and length
338 // fields will be inconsistent. This could cause a refinement
339 // thread to calculate the object size incorrectly.
340 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
341
342 // We will set up the first region as "starts humongous". This
343 // will also update the BOT covering all the regions to reflect
344 // that there is a single object that starts at the bottom of the
345 // first region.
346 first_hr->set_starts_humongous(obj_top);
347 first_hr->set_allocation_context(context);
348 // Then, if there are any, we will set up the "continues
349 // humongous" regions.
350 HeapRegion* hr = NULL;
351 for (uint i = first + 1; i < last; ++i) {
352 hr = region_at(i);
353 hr->set_continues_humongous(first_hr);
354 hr->set_allocation_context(context);
355 }
356
357 // Up to this point no concurrent thread would have been able to
358 // do any scanning on any region in this series. All the top
359 // fields still point to bottom, so the intersection between
360 // [bottom,top] and [card_start,card_end] will be empty. Before we
361 // update the top fields, we'll do a storestore to make sure that
362 // no thread sees the update to top before the zeroing of the
363 // object header and the BOT initialization.
364 OrderAccess::storestore();
365
366 // Now that the BOT and the object header have been initialized,
367 // we can update top of the "starts humongous" region.
368 first_hr->set_top(MIN2(first_hr->end(), obj_top));
369 if (_hr_printer.is_active()) {
370 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
371 }
372
373 // Now, we will update the top fields of the "continues humongous"
374 // regions.
375 hr = NULL;
376 for (uint i = first + 1; i < last; ++i) {
377 hr = region_at(i);
378 if ((i + 1) == last) {
379 // last continues humongous region
380 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
381 "new_top should fall on this region");
382 hr->set_top(obj_top);
383 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
384 } else {
385 // not last one
386 assert(obj_top > hr->end(), "obj_top should be above this region");
387 hr->set_top(hr->end());
388 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
389 }
390 }
391 // If we have continues humongous regions (hr != NULL), its top should
392 // match obj_top.
393 assert(hr == NULL || (hr->top() == obj_top), "sanity");
394 check_bitmaps("Humongous Region Allocation", first_hr);
395
396 increase_used(word_size * HeapWordSize);
397
398 for (uint i = first; i < last; ++i) {
399 _humongous_set.add(region_at(i));
400 }
401
402 return new_obj;
403 }
404
405 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
406 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
407 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
408 }
409
410 // If could fit into free regions w/o expansion, try.
411 // Otherwise, if can expand, do so.
412 // Otherwise, if using ex regions might help, try with ex given back.
413 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
414 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
415
416 verify_region_sets_optional();
417
418 uint first = G1_NO_HRM_INDEX;
419 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
420
421 if (obj_regions == 1) {
422 // Only one region to allocate, try to use a fast path by directly allocating
423 // from the free lists. Do not try to expand here, we will potentially do that
424 // later.
425 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
426 if (hr != NULL) {
427 first = hr->hrm_index();
428 }
429 } else {
430 // We can't allocate humongous regions spanning more than one region while
431 // cleanupComplete() is running, since some of the regions we find to be
432 // empty might not yet be added to the free list. It is not straightforward
433 // to know in which list they are on so that we can remove them. We only
434 // need to do this if we need to allocate more than one region to satisfy the
435 // current humongous allocation request. If we are only allocating one region
436 // we use the one-region region allocation code (see above), that already
437 // potentially waits for regions from the secondary free list.
438 wait_while_free_regions_coming();
439 append_secondary_free_list_if_not_empty_with_lock();
440
441 // Policy: Try only empty regions (i.e. already committed first). Maybe we
442 // are lucky enough to find some.
443 first = _hrm.find_contiguous_only_empty(obj_regions);
444 if (first != G1_NO_HRM_INDEX) {
445 _hrm.allocate_free_regions_starting_at(first, obj_regions);
446 }
447 }
448
449 if (first == G1_NO_HRM_INDEX) {
450 // Policy: We could not find enough regions for the humongous object in the
451 // free list. Look through the heap to find a mix of free and uncommitted regions.
452 // If so, try expansion.
453 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
454 if (first != G1_NO_HRM_INDEX) {
455 // We found something. Make sure these regions are committed, i.e. expand
456 // the heap. Alternatively we could do a defragmentation GC.
457 ergo_verbose1(ErgoHeapSizing,
458 "attempt heap expansion",
459 ergo_format_reason("humongous allocation request failed")
460 ergo_format_byte("allocation request"),
461 word_size * HeapWordSize);
462
463 _hrm.expand_at(first, obj_regions);
464 g1_policy()->record_new_heap_size(num_regions());
465
466 #ifdef ASSERT
467 for (uint i = first; i < first + obj_regions; ++i) {
468 HeapRegion* hr = region_at(i);
469 assert(hr->is_free(), "sanity");
470 assert(hr->is_empty(), "sanity");
471 assert(is_on_master_free_list(hr), "sanity");
472 }
473 #endif
474 _hrm.allocate_free_regions_starting_at(first, obj_regions);
475 } else {
476 // Policy: Potentially trigger a defragmentation GC.
477 }
478 }
479
480 HeapWord* result = NULL;
481 if (first != G1_NO_HRM_INDEX) {
482 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
483 word_size, context);
484 assert(result != NULL, "it should always return a valid result");
485
486 // A successful humongous object allocation changes the used space
487 // information of the old generation so we need to recalculate the
488 // sizes and update the jstat counters here.
489 g1mm()->update_sizes();
490 }
491
492 verify_region_sets_optional();
493
494 return result;
495 }
496
497 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
498 assert_heap_not_locked_and_not_at_safepoint();
499 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
500
501 uint dummy_gc_count_before;
502 uint dummy_gclocker_retry_count = 0;
503 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
504 }
505
506 HeapWord*
507 G1CollectedHeap::mem_allocate(size_t word_size,
508 bool* gc_overhead_limit_was_exceeded) {
509 assert_heap_not_locked_and_not_at_safepoint();
510
511 // Loop until the allocation is satisfied, or unsatisfied after GC.
512 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
513 uint gc_count_before;
514
515 HeapWord* result = NULL;
516 if (!is_humongous(word_size)) {
517 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
518 } else {
519 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
520 }
521 if (result != NULL) {
522 return result;
523 }
524
525 // Create the garbage collection operation...
526 VM_G1CollectForAllocation op(gc_count_before, word_size);
527 op.set_allocation_context(AllocationContext::current());
528
529 // ...and get the VM thread to execute it.
530 VMThread::execute(&op);
531
532 if (op.prologue_succeeded() && op.pause_succeeded()) {
533 // If the operation was successful we'll return the result even
534 // if it is NULL. If the allocation attempt failed immediately
535 // after a Full GC, it's unlikely we'll be able to allocate now.
536 HeapWord* result = op.result();
537 if (result != NULL && !is_humongous(word_size)) {
538 // Allocations that take place on VM operations do not do any
539 // card dirtying and we have to do it here. We only have to do
540 // this for non-humongous allocations, though.
541 dirty_young_block(result, word_size);
542 }
543 return result;
544 } else {
545 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
546 return NULL;
547 }
548 assert(op.result() == NULL,
549 "the result should be NULL if the VM op did not succeed");
550 }
551
552 // Give a warning if we seem to be looping forever.
553 if ((QueuedAllocationWarningCount > 0) &&
554 (try_count % QueuedAllocationWarningCount == 0)) {
555 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
556 }
557 }
558
559 ShouldNotReachHere();
560 return NULL;
561 }
562
563 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
564 AllocationContext_t context,
565 uint* gc_count_before_ret,
566 uint* gclocker_retry_count_ret) {
567 // Make sure you read the note in attempt_allocation_humongous().
568
569 assert_heap_not_locked_and_not_at_safepoint();
570 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
571 "be called for humongous allocation requests");
572
573 // We should only get here after the first-level allocation attempt
574 // (attempt_allocation()) failed to allocate.
575
576 // We will loop until a) we manage to successfully perform the
577 // allocation or b) we successfully schedule a collection which
578 // fails to perform the allocation. b) is the only case when we'll
579 // return NULL.
580 HeapWord* result = NULL;
581 for (int try_count = 1; /* we'll return */; try_count += 1) {
582 bool should_try_gc;
583 uint gc_count_before;
584
585 {
586 MutexLockerEx x(Heap_lock);
587 result = _allocator->attempt_allocation_locked(word_size, context);
588 if (result != NULL) {
589 return result;
590 }
591
592 if (GC_locker::is_active_and_needs_gc()) {
593 if (g1_policy()->can_expand_young_list()) {
594 // No need for an ergo verbose message here,
595 // can_expand_young_list() does this when it returns true.
596 result = _allocator->attempt_allocation_force(word_size, context);
597 if (result != NULL) {
598 return result;
599 }
600 }
601 should_try_gc = false;
602 } else {
603 // The GCLocker may not be active but the GCLocker initiated
604 // GC may not yet have been performed (GCLocker::needs_gc()
605 // returns true). In this case we do not try this GC and
606 // wait until the GCLocker initiated GC is performed, and
607 // then retry the allocation.
608 if (GC_locker::needs_gc()) {
609 should_try_gc = false;
610 } else {
611 // Read the GC count while still holding the Heap_lock.
612 gc_count_before = total_collections();
613 should_try_gc = true;
614 }
615 }
616 }
617
618 if (should_try_gc) {
619 bool succeeded;
620 result = do_collection_pause(word_size, gc_count_before, &succeeded,
621 GCCause::_g1_inc_collection_pause);
622 if (result != NULL) {
623 assert(succeeded, "only way to get back a non-NULL result");
624 return result;
625 }
626
627 if (succeeded) {
628 // If we get here we successfully scheduled a collection which
629 // failed to allocate. No point in trying to allocate
630 // further. We'll just return NULL.
631 MutexLockerEx x(Heap_lock);
632 *gc_count_before_ret = total_collections();
633 return NULL;
634 }
635 } else {
636 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
637 MutexLockerEx x(Heap_lock);
638 *gc_count_before_ret = total_collections();
639 return NULL;
640 }
641 // The GCLocker is either active or the GCLocker initiated
642 // GC has not yet been performed. Stall until it is and
643 // then retry the allocation.
644 GC_locker::stall_until_clear();
645 (*gclocker_retry_count_ret) += 1;
646 }
647
648 // We can reach here if we were unsuccessful in scheduling a
649 // collection (because another thread beat us to it) or if we were
650 // stalled due to the GC locker. In either can we should retry the
651 // allocation attempt in case another thread successfully
652 // performed a collection and reclaimed enough space. We do the
653 // first attempt (without holding the Heap_lock) here and the
654 // follow-on attempt will be at the start of the next loop
655 // iteration (after taking the Heap_lock).
656 result = _allocator->attempt_allocation(word_size, context);
657 if (result != NULL) {
658 return result;
659 }
660
661 // Give a warning if we seem to be looping forever.
662 if ((QueuedAllocationWarningCount > 0) &&
663 (try_count % QueuedAllocationWarningCount == 0)) {
664 warning("G1CollectedHeap::attempt_allocation_slow() "
665 "retries %d times", try_count);
666 }
667 }
668
669 ShouldNotReachHere();
670 return NULL;
671 }
672
673 void G1CollectedHeap::begin_archive_alloc_range() {
674 assert_at_safepoint(true /* should_be_vm_thread */);
675 if (_archive_allocator == NULL) {
676 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
677 }
678 }
679
680 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
681 // Allocations in archive regions cannot be of a size that would be considered
682 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
683 // may be different at archive-restore time.
684 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
685 }
686
687 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
688 assert_at_safepoint(true /* should_be_vm_thread */);
689 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
690 if (is_archive_alloc_too_large(word_size)) {
691 return NULL;
692 }
693 return _archive_allocator->archive_mem_allocate(word_size);
694 }
695
696 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
697 size_t end_alignment_in_bytes) {
698 assert_at_safepoint(true /* should_be_vm_thread */);
699 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
700
701 // Call complete_archive to do the real work, filling in the MemRegion
702 // array with the archive regions.
703 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
704 delete _archive_allocator;
705 _archive_allocator = NULL;
706 }
707
708 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
709 assert(ranges != NULL, "MemRegion array NULL");
710 assert(count != 0, "No MemRegions provided");
711 MemRegion reserved = _hrm.reserved();
712 for (size_t i = 0; i < count; i++) {
713 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
714 return false;
715 }
716 }
717 return true;
718 }
719
720 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
721 assert(!is_init_completed(), "Expect to be called at JVM init time");
722 assert(ranges != NULL, "MemRegion array NULL");
723 assert(count != 0, "No MemRegions provided");
724 MutexLockerEx x(Heap_lock);
725
726 MemRegion reserved = _hrm.reserved();
727 HeapWord* prev_last_addr = NULL;
728 HeapRegion* prev_last_region = NULL;
729
730 // Temporarily disable pretouching of heap pages. This interface is used
731 // when mmap'ing archived heap data in, so pre-touching is wasted.
732 FlagSetting fs(AlwaysPreTouch, false);
733
734 // Enable archive object checking in G1MarkSweep. We have to let it know
735 // about each archive range, so that objects in those ranges aren't marked.
736 G1MarkSweep::enable_archive_object_check();
737
738 // For each specified MemRegion range, allocate the corresponding G1
739 // regions and mark them as archive regions. We expect the ranges in
740 // ascending starting address order, without overlap.
741 for (size_t i = 0; i < count; i++) {
742 MemRegion curr_range = ranges[i];
743 HeapWord* start_address = curr_range.start();
744 size_t word_size = curr_range.word_size();
745 HeapWord* last_address = curr_range.last();
746 size_t commits = 0;
747
748 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
749 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
750 p2i(start_address), p2i(last_address));
751 guarantee(start_address > prev_last_addr,
752 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
753 p2i(start_address), p2i(prev_last_addr));
754 prev_last_addr = last_address;
755
756 // Check for ranges that start in the same G1 region in which the previous
757 // range ended, and adjust the start address so we don't try to allocate
758 // the same region again. If the current range is entirely within that
759 // region, skip it, just adjusting the recorded top.
760 HeapRegion* start_region = _hrm.addr_to_region(start_address);
761 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
762 start_address = start_region->end();
763 if (start_address > last_address) {
764 increase_used(word_size * HeapWordSize);
765 start_region->set_top(last_address + 1);
766 continue;
767 }
768 start_region->set_top(start_address);
769 curr_range = MemRegion(start_address, last_address + 1);
770 start_region = _hrm.addr_to_region(start_address);
771 }
772
773 // Perform the actual region allocation, exiting if it fails.
774 // Then note how much new space we have allocated.
775 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
776 return false;
777 }
778 increase_used(word_size * HeapWordSize);
779 if (commits != 0) {
780 ergo_verbose1(ErgoHeapSizing,
781 "attempt heap expansion",
782 ergo_format_reason("allocate archive regions")
783 ergo_format_byte("total size"),
784 HeapRegion::GrainWords * HeapWordSize * commits);
785 }
786
787 // Mark each G1 region touched by the range as archive, add it to the old set,
788 // and set the allocation context and top.
789 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
790 HeapRegion* last_region = _hrm.addr_to_region(last_address);
791 prev_last_region = last_region;
792
793 while (curr_region != NULL) {
794 assert(curr_region->is_empty() && !curr_region->is_pinned(),
795 "Region already in use (index %u)", curr_region->hrm_index());
796 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
797 curr_region->set_allocation_context(AllocationContext::system());
798 curr_region->set_archive();
799 _old_set.add(curr_region);
800 if (curr_region != last_region) {
801 curr_region->set_top(curr_region->end());
802 curr_region = _hrm.next_region_in_heap(curr_region);
803 } else {
804 curr_region->set_top(last_address + 1);
805 curr_region = NULL;
806 }
807 }
808
809 // Notify mark-sweep of the archive range.
810 G1MarkSweep::set_range_archive(curr_range, true);
811 }
812 return true;
813 }
814
815 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
816 assert(!is_init_completed(), "Expect to be called at JVM init time");
817 assert(ranges != NULL, "MemRegion array NULL");
818 assert(count != 0, "No MemRegions provided");
819 MemRegion reserved = _hrm.reserved();
820 HeapWord *prev_last_addr = NULL;
821 HeapRegion* prev_last_region = NULL;
822
823 // For each MemRegion, create filler objects, if needed, in the G1 regions
824 // that contain the address range. The address range actually within the
825 // MemRegion will not be modified. That is assumed to have been initialized
826 // elsewhere, probably via an mmap of archived heap data.
827 MutexLockerEx x(Heap_lock);
828 for (size_t i = 0; i < count; i++) {
829 HeapWord* start_address = ranges[i].start();
830 HeapWord* last_address = ranges[i].last();
831
832 assert(reserved.contains(start_address) && reserved.contains(last_address),
833 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
834 p2i(start_address), p2i(last_address));
835 assert(start_address > prev_last_addr,
836 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
837 p2i(start_address), p2i(prev_last_addr));
838
839 HeapRegion* start_region = _hrm.addr_to_region(start_address);
840 HeapRegion* last_region = _hrm.addr_to_region(last_address);
841 HeapWord* bottom_address = start_region->bottom();
842
843 // Check for a range beginning in the same region in which the
844 // previous one ended.
845 if (start_region == prev_last_region) {
846 bottom_address = prev_last_addr + 1;
847 }
848
849 // Verify that the regions were all marked as archive regions by
850 // alloc_archive_regions.
851 HeapRegion* curr_region = start_region;
852 while (curr_region != NULL) {
853 guarantee(curr_region->is_archive(),
854 "Expected archive region at index %u", curr_region->hrm_index());
855 if (curr_region != last_region) {
856 curr_region = _hrm.next_region_in_heap(curr_region);
857 } else {
858 curr_region = NULL;
859 }
860 }
861
862 prev_last_addr = last_address;
863 prev_last_region = last_region;
864
865 // Fill the memory below the allocated range with dummy object(s),
866 // if the region bottom does not match the range start, or if the previous
867 // range ended within the same G1 region, and there is a gap.
868 if (start_address != bottom_address) {
869 size_t fill_size = pointer_delta(start_address, bottom_address);
870 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
871 increase_used(fill_size * HeapWordSize);
872 }
873 }
874 }
875
876 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
877 uint* gc_count_before_ret,
878 uint* gclocker_retry_count_ret) {
879 assert_heap_not_locked_and_not_at_safepoint();
880 assert(!is_humongous(word_size), "attempt_allocation() should not "
881 "be called for humongous allocation requests");
882
883 AllocationContext_t context = AllocationContext::current();
884 HeapWord* result = _allocator->attempt_allocation(word_size, context);
885
886 if (result == NULL) {
887 result = attempt_allocation_slow(word_size,
888 context,
889 gc_count_before_ret,
890 gclocker_retry_count_ret);
891 }
892 assert_heap_not_locked();
893 if (result != NULL) {
894 dirty_young_block(result, word_size);
895 }
896 return result;
897 }
898
899 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
900 assert(!is_init_completed(), "Expect to be called at JVM init time");
901 assert(ranges != NULL, "MemRegion array NULL");
902 assert(count != 0, "No MemRegions provided");
903 MemRegion reserved = _hrm.reserved();
904 HeapWord* prev_last_addr = NULL;
905 HeapRegion* prev_last_region = NULL;
906 size_t size_used = 0;
907 size_t uncommitted_regions = 0;
908
909 // For each Memregion, free the G1 regions that constitute it, and
910 // notify mark-sweep that the range is no longer to be considered 'archive.'
911 MutexLockerEx x(Heap_lock);
912 for (size_t i = 0; i < count; i++) {
913 HeapWord* start_address = ranges[i].start();
914 HeapWord* last_address = ranges[i].last();
915
916 assert(reserved.contains(start_address) && reserved.contains(last_address),
917 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
918 p2i(start_address), p2i(last_address));
919 assert(start_address > prev_last_addr,
920 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
921 p2i(start_address), p2i(prev_last_addr));
922 size_used += ranges[i].byte_size();
923 prev_last_addr = last_address;
924
925 HeapRegion* start_region = _hrm.addr_to_region(start_address);
926 HeapRegion* last_region = _hrm.addr_to_region(last_address);
927
928 // Check for ranges that start in the same G1 region in which the previous
929 // range ended, and adjust the start address so we don't try to free
930 // the same region again. If the current range is entirely within that
931 // region, skip it.
932 if (start_region == prev_last_region) {
933 start_address = start_region->end();
934 if (start_address > last_address) {
935 continue;
936 }
937 start_region = _hrm.addr_to_region(start_address);
938 }
939 prev_last_region = last_region;
940
941 // After verifying that each region was marked as an archive region by
942 // alloc_archive_regions, set it free and empty and uncommit it.
943 HeapRegion* curr_region = start_region;
944 while (curr_region != NULL) {
945 guarantee(curr_region->is_archive(),
946 "Expected archive region at index %u", curr_region->hrm_index());
947 uint curr_index = curr_region->hrm_index();
948 _old_set.remove(curr_region);
949 curr_region->set_free();
950 curr_region->set_top(curr_region->bottom());
951 if (curr_region != last_region) {
952 curr_region = _hrm.next_region_in_heap(curr_region);
953 } else {
954 curr_region = NULL;
955 }
956 _hrm.shrink_at(curr_index, 1);
957 uncommitted_regions++;
958 }
959
960 // Notify mark-sweep that this is no longer an archive range.
961 G1MarkSweep::set_range_archive(ranges[i], false);
962 }
963
964 if (uncommitted_regions != 0) {
965 ergo_verbose1(ErgoHeapSizing,
966 "attempt heap shrinking",
967 ergo_format_reason("uncommitted archive regions")
968 ergo_format_byte("total size"),
969 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
970 }
971 decrease_used(size_used);
972 }
973
974 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
975 uint* gc_count_before_ret,
976 uint* gclocker_retry_count_ret) {
977 // The structure of this method has a lot of similarities to
978 // attempt_allocation_slow(). The reason these two were not merged
979 // into a single one is that such a method would require several "if
980 // allocation is not humongous do this, otherwise do that"
981 // conditional paths which would obscure its flow. In fact, an early
982 // version of this code did use a unified method which was harder to
983 // follow and, as a result, it had subtle bugs that were hard to
984 // track down. So keeping these two methods separate allows each to
985 // be more readable. It will be good to keep these two in sync as
986 // much as possible.
987
988 assert_heap_not_locked_and_not_at_safepoint();
989 assert(is_humongous(word_size), "attempt_allocation_humongous() "
990 "should only be called for humongous allocations");
991
992 // Humongous objects can exhaust the heap quickly, so we should check if we
993 // need to start a marking cycle at each humongous object allocation. We do
994 // the check before we do the actual allocation. The reason for doing it
995 // before the allocation is that we avoid having to keep track of the newly
996 // allocated memory while we do a GC.
997 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
998 word_size)) {
999 collect(GCCause::_g1_humongous_allocation);
1000 }
1001
1002 // We will loop until a) we manage to successfully perform the
1003 // allocation or b) we successfully schedule a collection which
1004 // fails to perform the allocation. b) is the only case when we'll
1005 // return NULL.
1006 HeapWord* result = NULL;
1007 for (int try_count = 1; /* we'll return */; try_count += 1) {
1008 bool should_try_gc;
1009 uint gc_count_before;
1010
1011 {
1012 MutexLockerEx x(Heap_lock);
1013
1014 // Given that humongous objects are not allocated in young
1015 // regions, we'll first try to do the allocation without doing a
1016 // collection hoping that there's enough space in the heap.
1017 result = humongous_obj_allocate(word_size, AllocationContext::current());
1018 if (result != NULL) {
1019 g1_policy()->add_last_old_allocated_bytes(humongous_obj_size_in_regions(word_size) * HeapRegion::GrainBytes);
1020 return result;
1021 }
1022
1023 if (GC_locker::is_active_and_needs_gc()) {
1024 should_try_gc = false;
1025 } else {
1026 // The GCLocker may not be active but the GCLocker initiated
1027 // GC may not yet have been performed (GCLocker::needs_gc()
1028 // returns true). In this case we do not try this GC and
1029 // wait until the GCLocker initiated GC is performed, and
1030 // then retry the allocation.
1031 if (GC_locker::needs_gc()) {
1032 should_try_gc = false;
1033 } else {
1034 // Read the GC count while still holding the Heap_lock.
1035 gc_count_before = total_collections();
1036 should_try_gc = true;
1037 }
1038 }
1039 }
1040
1041 if (should_try_gc) {
1042 // If we failed to allocate the humongous object, we should try to
1043 // do a collection pause (if we're allowed) in case it reclaims
1044 // enough space for the allocation to succeed after the pause.
1045
1046 bool succeeded;
1047 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1048 GCCause::_g1_humongous_allocation);
1049 if (result != NULL) {
1050 assert(succeeded, "only way to get back a non-NULL result");
1051 return result;
1052 }
1053
1054 if (succeeded) {
1055 // If we get here we successfully scheduled a collection which
1056 // failed to allocate. No point in trying to allocate
1057 // further. We'll just return NULL.
1058 MutexLockerEx x(Heap_lock);
1059 *gc_count_before_ret = total_collections();
1060 return NULL;
1061 }
1062 } else {
1063 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1064 MutexLockerEx x(Heap_lock);
1065 *gc_count_before_ret = total_collections();
1066 return NULL;
1067 }
1068 // The GCLocker is either active or the GCLocker initiated
1069 // GC has not yet been performed. Stall until it is and
1070 // then retry the allocation.
1071 GC_locker::stall_until_clear();
1072 (*gclocker_retry_count_ret) += 1;
1073 }
1074
1075 // We can reach here if we were unsuccessful in scheduling a
1076 // collection (because another thread beat us to it) or if we were
1077 // stalled due to the GC locker. In either can we should retry the
1078 // allocation attempt in case another thread successfully
1079 // performed a collection and reclaimed enough space. Give a
1080 // warning if we seem to be looping forever.
1081
1082 if ((QueuedAllocationWarningCount > 0) &&
1083 (try_count % QueuedAllocationWarningCount == 0)) {
1084 warning("G1CollectedHeap::attempt_allocation_humongous() "
1085 "retries %d times", try_count);
1086 }
1087 }
1088
1089 ShouldNotReachHere();
1090 return NULL;
1091 }
1092
1093 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1094 AllocationContext_t context,
1095 bool expect_null_mutator_alloc_region) {
1096 assert_at_safepoint(true /* should_be_vm_thread */);
1097 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1098 "the current alloc region was unexpectedly found to be non-NULL");
1099
1100 if (!is_humongous(word_size)) {
1101 return _allocator->attempt_allocation_locked(word_size, context);
1102 } else {
1103 HeapWord* result = humongous_obj_allocate(word_size, context);
1104 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1105 collector_state()->set_initiate_conc_mark_if_possible(true);
1106 }
1107 return result;
1108 }
1109
1110 ShouldNotReachHere();
1111 }
1112
1113 class PostMCRemSetClearClosure: public HeapRegionClosure {
1114 G1CollectedHeap* _g1h;
1115 ModRefBarrierSet* _mr_bs;
1116 public:
1117 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1118 _g1h(g1h), _mr_bs(mr_bs) {}
1119
1120 bool doHeapRegion(HeapRegion* r) {
1121 HeapRegionRemSet* hrrs = r->rem_set();
1122
1123 _g1h->reset_gc_time_stamps(r);
1124
1125 if (r->is_continues_humongous()) {
1126 // We'll assert that the strong code root list and RSet is empty
1127 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1128 assert(hrrs->occupied() == 0, "RSet should be empty");
1129 } else {
1130 hrrs->clear();
1131 }
1132 // You might think here that we could clear just the cards
1133 // corresponding to the used region. But no: if we leave a dirty card
1134 // in a region we might allocate into, then it would prevent that card
1135 // from being enqueued, and cause it to be missed.
1136 // Re: the performance cost: we shouldn't be doing full GC anyway!
1137 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1138
1139 return false;
1140 }
1141 };
1142
1143 void G1CollectedHeap::clear_rsets_post_compaction() {
1144 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1145 heap_region_iterate(&rs_clear);
1146 }
1147
1148 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1149 G1CollectedHeap* _g1h;
1150 UpdateRSOopClosure _cl;
1151 public:
1152 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1153 _cl(g1->g1_rem_set(), worker_i),
1154 _g1h(g1)
1155 { }
1156
1157 bool doHeapRegion(HeapRegion* r) {
1158 if (!r->is_continues_humongous()) {
1159 _cl.set_from(r);
1160 r->oop_iterate(&_cl);
1161 }
1162 return false;
1163 }
1164 };
1165
1166 class ParRebuildRSTask: public AbstractGangTask {
1167 G1CollectedHeap* _g1;
1168 HeapRegionClaimer _hrclaimer;
1169
1170 public:
1171 ParRebuildRSTask(G1CollectedHeap* g1) :
1172 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1173
1174 void work(uint worker_id) {
1175 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1176 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1177 }
1178 };
1179
1180 class PostCompactionPrinterClosure: public HeapRegionClosure {
1181 private:
1182 G1HRPrinter* _hr_printer;
1183 public:
1184 bool doHeapRegion(HeapRegion* hr) {
1185 assert(!hr->is_young(), "not expecting to find young regions");
1186 if (hr->is_free()) {
1187 // We only generate output for non-empty regions.
1188 } else if (hr->is_starts_humongous()) {
1189 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1190 } else if (hr->is_continues_humongous()) {
1191 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1192 } else if (hr->is_archive()) {
1193 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1194 } else if (hr->is_old()) {
1195 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1196 } else {
1197 ShouldNotReachHere();
1198 }
1199 return false;
1200 }
1201
1202 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1203 : _hr_printer(hr_printer) { }
1204 };
1205
1206 void G1CollectedHeap::print_hrm_post_compaction() {
1207 PostCompactionPrinterClosure cl(hr_printer());
1208 heap_region_iterate(&cl);
1209 }
1210
1211 bool G1CollectedHeap::do_collection(bool explicit_gc,
1212 bool clear_all_soft_refs,
1213 size_t word_size) {
1214 assert_at_safepoint(true /* should_be_vm_thread */);
1215
1216 if (GC_locker::check_active_before_gc()) {
1217 return false;
1218 }
1219
1220 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1221 gc_timer->register_gc_start();
1222
1223 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1224 GCIdMark gc_id_mark;
1225 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1226
1227 SvcGCMarker sgcm(SvcGCMarker::FULL);
1228 ResourceMark rm;
1229
1230 G1Log::update_level();
1231 print_heap_before_gc();
1232 trace_heap_before_gc(gc_tracer);
1233
1234 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1235
1236 verify_region_sets_optional();
1237
1238 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1239 collector_policy()->should_clear_all_soft_refs();
1240
1241 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1242
1243 {
1244 IsGCActiveMark x;
1245
1246 // Timing
1247 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1248 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1249
1250 {
1251 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1252 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1253 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1254
1255 g1_policy()->record_full_collection_start();
1256
1257 // Note: When we have a more flexible GC logging framework that
1258 // allows us to add optional attributes to a GC log record we
1259 // could consider timing and reporting how long we wait in the
1260 // following two methods.
1261 wait_while_free_regions_coming();
1262 // If we start the compaction before the CM threads finish
1263 // scanning the root regions we might trip them over as we'll
1264 // be moving objects / updating references. So let's wait until
1265 // they are done. By telling them to abort, they should complete
1266 // early.
1267 _cm->root_regions()->abort();
1268 _cm->root_regions()->wait_until_scan_finished();
1269 append_secondary_free_list_if_not_empty_with_lock();
1270
1271 gc_prologue(true);
1272 increment_total_collections(true /* full gc */);
1273 increment_old_marking_cycles_started();
1274
1275 assert(used() == recalculate_used(), "Should be equal");
1276
1277 verify_before_gc();
1278
1279 check_bitmaps("Full GC Start");
1280 pre_full_gc_dump(gc_timer);
1281
1282 #if defined(COMPILER2) || INCLUDE_JVMCI
1283 DerivedPointerTable::clear();
1284 #endif
1285
1286 // Disable discovery and empty the discovered lists
1287 // for the CM ref processor.
1288 ref_processor_cm()->disable_discovery();
1289 ref_processor_cm()->abandon_partial_discovery();
1290 ref_processor_cm()->verify_no_references_recorded();
1291
1292 // Abandon current iterations of concurrent marking and concurrent
1293 // refinement, if any are in progress. We have to do this before
1294 // wait_until_scan_finished() below.
1295 concurrent_mark()->abort();
1296
1297 // Make sure we'll choose a new allocation region afterwards.
1298 _allocator->release_mutator_alloc_region();
1299 _allocator->abandon_gc_alloc_regions();
1300 g1_rem_set()->cleanupHRRS();
1301
1302 // We should call this after we retire any currently active alloc
1303 // regions so that all the ALLOC / RETIRE events are generated
1304 // before the start GC event.
1305 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1306
1307 // We may have added regions to the current incremental collection
1308 // set between the last GC or pause and now. We need to clear the
1309 // incremental collection set and then start rebuilding it afresh
1310 // after this full GC.
1311 abandon_collection_set(g1_policy()->inc_cset_head());
1312 g1_policy()->clear_incremental_cset();
1313 g1_policy()->stop_incremental_cset_building();
1314
1315 tear_down_region_sets(false /* free_list_only */);
1316 collector_state()->set_gcs_are_young(true);
1317
1318 // See the comments in g1CollectedHeap.hpp and
1319 // G1CollectedHeap::ref_processing_init() about
1320 // how reference processing currently works in G1.
1321
1322 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1323 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1324
1325 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1326 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1327
1328 ref_processor_stw()->enable_discovery();
1329 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1330
1331 // Do collection work
1332 {
1333 HandleMark hm; // Discard invalid handles created during gc
1334 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1335 }
1336
1337 assert(num_free_regions() == 0, "we should not have added any free regions");
1338 rebuild_region_sets(false /* free_list_only */);
1339
1340 // Enqueue any discovered reference objects that have
1341 // not been removed from the discovered lists.
1342 ref_processor_stw()->enqueue_discovered_references();
1343
1344 #if defined(COMPILER2) || INCLUDE_JVMCI
1345 DerivedPointerTable::update_pointers();
1346 #endif
1347
1348 MemoryService::track_memory_usage();
1349
1350 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1351 ref_processor_stw()->verify_no_references_recorded();
1352
1353 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1354 ClassLoaderDataGraph::purge();
1355 MetaspaceAux::verify_metrics();
1356
1357 // Note: since we've just done a full GC, concurrent
1358 // marking is no longer active. Therefore we need not
1359 // re-enable reference discovery for the CM ref processor.
1360 // That will be done at the start of the next marking cycle.
1361 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1362 ref_processor_cm()->verify_no_references_recorded();
1363
1364 reset_gc_time_stamp();
1365 // Since everything potentially moved, we will clear all remembered
1366 // sets, and clear all cards. Later we will rebuild remembered
1367 // sets. We will also reset the GC time stamps of the regions.
1368 clear_rsets_post_compaction();
1369 check_gc_time_stamps();
1370
1371 // Resize the heap if necessary.
1372 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1373
1374 if (_hr_printer.is_active()) {
1375 // We should do this after we potentially resize the heap so
1376 // that all the COMMIT / UNCOMMIT events are generated before
1377 // the end GC event.
1378
1379 print_hrm_post_compaction();
1380 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1381 }
1382
1383 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1384 if (hot_card_cache->use_cache()) {
1385 hot_card_cache->reset_card_counts();
1386 hot_card_cache->reset_hot_cache();
1387 }
1388
1389 // Rebuild remembered sets of all regions.
1390 uint n_workers =
1391 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1392 workers()->active_workers(),
1393 Threads::number_of_non_daemon_threads());
1394 workers()->set_active_workers(n_workers);
1395
1396 ParRebuildRSTask rebuild_rs_task(this);
1397 workers()->run_task(&rebuild_rs_task);
1398
1399 // Rebuild the strong code root lists for each region
1400 rebuild_strong_code_roots();
1401
1402 if (true) { // FIXME
1403 MetaspaceGC::compute_new_size();
1404 }
1405
1406 #ifdef TRACESPINNING
1407 ParallelTaskTerminator::print_termination_counts();
1408 #endif
1409
1410 // Discard all rset updates
1411 JavaThread::dirty_card_queue_set().abandon_logs();
1412 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1413
1414 _young_list->reset_sampled_info();
1415 // At this point there should be no regions in the
1416 // entire heap tagged as young.
1417 assert(check_young_list_empty(true /* check_heap */),
1418 "young list should be empty at this point");
1419
1420 // Update the number of full collections that have been completed.
1421 increment_old_marking_cycles_completed(false /* concurrent */);
1422
1423 _hrm.verify_optional();
1424 verify_region_sets_optional();
1425
1426 verify_after_gc();
1427
1428 // Clear the previous marking bitmap, if needed for bitmap verification.
1429 // Note we cannot do this when we clear the next marking bitmap in
1430 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1431 // objects marked during a full GC against the previous bitmap.
1432 // But we need to clear it before calling check_bitmaps below since
1433 // the full GC has compacted objects and updated TAMS but not updated
1434 // the prev bitmap.
1435 if (G1VerifyBitmaps) {
1436 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1437 }
1438 check_bitmaps("Full GC End");
1439
1440 // Start a new incremental collection set for the next pause
1441 assert(g1_policy()->collection_set() == NULL, "must be");
1442 g1_policy()->start_incremental_cset_building();
1443
1444 clear_cset_fast_test();
1445
1446 _allocator->init_mutator_alloc_region();
1447
1448 g1_policy()->record_full_collection_end();
1449
1450 if (G1Log::fine()) {
1451 g1_policy()->print_heap_transition();
1452 }
1453
1454 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1455 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1456 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1457 // before any GC notifications are raised.
1458 g1mm()->update_sizes();
1459
1460 gc_epilogue(true);
1461 }
1462
1463 if (G1Log::finer()) {
1464 g1_policy()->print_detailed_heap_transition(true /* full */);
1465 }
1466
1467 print_heap_after_gc();
1468 trace_heap_after_gc(gc_tracer);
1469
1470 post_full_gc_dump(gc_timer);
1471
1472 gc_timer->register_gc_end();
1473 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1474 }
1475
1476 return true;
1477 }
1478
1479 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1480 // do_collection() will return whether it succeeded in performing
1481 // the GC. Currently, there is no facility on the
1482 // do_full_collection() API to notify the caller than the collection
1483 // did not succeed (e.g., because it was locked out by the GC
1484 // locker). So, right now, we'll ignore the return value.
1485 bool dummy = do_collection(true, /* explicit_gc */
1486 clear_all_soft_refs,
1487 0 /* word_size */);
1488 }
1489
1490 // This code is mostly copied from TenuredGeneration.
1491 void
1492 G1CollectedHeap::
1493 resize_if_necessary_after_full_collection(size_t word_size) {
1494 // Include the current allocation, if any, and bytes that will be
1495 // pre-allocated to support collections, as "used".
1496 const size_t used_after_gc = used();
1497 const size_t capacity_after_gc = capacity();
1498 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1499
1500 // This is enforced in arguments.cpp.
1501 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1502 "otherwise the code below doesn't make sense");
1503
1504 // We don't have floating point command-line arguments
1505 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1506 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1507 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1508 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1509
1510 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1511 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1512
1513 // We have to be careful here as these two calculations can overflow
1514 // 32-bit size_t's.
1515 double used_after_gc_d = (double) used_after_gc;
1516 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1517 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1518
1519 // Let's make sure that they are both under the max heap size, which
1520 // by default will make them fit into a size_t.
1521 double desired_capacity_upper_bound = (double) max_heap_size;
1522 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1523 desired_capacity_upper_bound);
1524 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1525 desired_capacity_upper_bound);
1526
1527 // We can now safely turn them into size_t's.
1528 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1529 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1530
1531 // This assert only makes sense here, before we adjust them
1532 // with respect to the min and max heap size.
1533 assert(minimum_desired_capacity <= maximum_desired_capacity,
1534 "minimum_desired_capacity = " SIZE_FORMAT ", "
1535 "maximum_desired_capacity = " SIZE_FORMAT,
1536 minimum_desired_capacity, maximum_desired_capacity);
1537
1538 // Should not be greater than the heap max size. No need to adjust
1539 // it with respect to the heap min size as it's a lower bound (i.e.,
1540 // we'll try to make the capacity larger than it, not smaller).
1541 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1542 // Should not be less than the heap min size. No need to adjust it
1543 // with respect to the heap max size as it's an upper bound (i.e.,
1544 // we'll try to make the capacity smaller than it, not greater).
1545 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1546
1547 if (capacity_after_gc < minimum_desired_capacity) {
1548 // Don't expand unless it's significant
1549 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1550 ergo_verbose4(ErgoHeapSizing,
1551 "attempt heap expansion",
1552 ergo_format_reason("capacity lower than "
1553 "min desired capacity after Full GC")
1554 ergo_format_byte("capacity")
1555 ergo_format_byte("occupancy")
1556 ergo_format_byte_perc("min desired capacity"),
1557 capacity_after_gc, used_after_gc,
1558 minimum_desired_capacity, (double) MinHeapFreeRatio);
1559 expand(expand_bytes);
1560
1561 // No expansion, now see if we want to shrink
1562 } else if (capacity_after_gc > maximum_desired_capacity) {
1563 // Capacity too large, compute shrinking size
1564 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1565 ergo_verbose4(ErgoHeapSizing,
1566 "attempt heap shrinking",
1567 ergo_format_reason("capacity higher than "
1568 "max desired capacity after Full GC")
1569 ergo_format_byte("capacity")
1570 ergo_format_byte("occupancy")
1571 ergo_format_byte_perc("max desired capacity"),
1572 capacity_after_gc, used_after_gc,
1573 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1574 shrink(shrink_bytes);
1575 }
1576 }
1577
1578 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1579 AllocationContext_t context,
1580 bool do_gc,
1581 bool clear_all_soft_refs,
1582 bool expect_null_mutator_alloc_region,
1583 bool* gc_succeeded) {
1584 *gc_succeeded = true;
1585 // Let's attempt the allocation first.
1586 HeapWord* result =
1587 attempt_allocation_at_safepoint(word_size,
1588 context,
1589 expect_null_mutator_alloc_region);
1590 if (result != NULL) {
1591 assert(*gc_succeeded, "sanity");
1592 return result;
1593 }
1594
1595 // In a G1 heap, we're supposed to keep allocation from failing by
1596 // incremental pauses. Therefore, at least for now, we'll favor
1597 // expansion over collection. (This might change in the future if we can
1598 // do something smarter than full collection to satisfy a failed alloc.)
1599 result = expand_and_allocate(word_size, context);
1600 if (result != NULL) {
1601 assert(*gc_succeeded, "sanity");
1602 return result;
1603 }
1604
1605 if (do_gc) {
1606 // Expansion didn't work, we'll try to do a Full GC.
1607 *gc_succeeded = do_collection(false, /* explicit_gc */
1608 clear_all_soft_refs,
1609 word_size);
1610 }
1611
1612 return NULL;
1613 }
1614
1615 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1616 AllocationContext_t context,
1617 bool* succeeded) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 // Attempts to allocate followed by Full GC.
1621 HeapWord* result =
1622 satisfy_failed_allocation_helper(word_size,
1623 context,
1624 true, /* do_gc */
1625 false, /* clear_all_soft_refs */
1626 false, /* expect_null_mutator_alloc_region */
1627 succeeded);
1628
1629 if (result != NULL || !*succeeded) {
1630 return result;
1631 }
1632
1633 // Attempts to allocate followed by Full GC that will collect all soft references.
1634 result = satisfy_failed_allocation_helper(word_size,
1635 context,
1636 true, /* do_gc */
1637 true, /* clear_all_soft_refs */
1638 true, /* expect_null_mutator_alloc_region */
1639 succeeded);
1640
1641 if (result != NULL || !*succeeded) {
1642 return result;
1643 }
1644
1645 // Attempts to allocate, no GC
1646 result = satisfy_failed_allocation_helper(word_size,
1647 context,
1648 false, /* do_gc */
1649 false, /* clear_all_soft_refs */
1650 true, /* expect_null_mutator_alloc_region */
1651 succeeded);
1652
1653 if (result != NULL) {
1654 assert(*succeeded, "sanity");
1655 return result;
1656 }
1657
1658 assert(!collector_policy()->should_clear_all_soft_refs(),
1659 "Flag should have been handled and cleared prior to this point");
1660
1661 // What else? We might try synchronous finalization later. If the total
1662 // space available is large enough for the allocation, then a more
1663 // complete compaction phase than we've tried so far might be
1664 // appropriate.
1665 assert(*succeeded, "sanity");
1666 return NULL;
1667 }
1668
1669 // Attempting to expand the heap sufficiently
1670 // to support an allocation of the given "word_size". If
1671 // successful, perform the allocation and return the address of the
1672 // allocated block, or else "NULL".
1673
1674 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1675 assert_at_safepoint(true /* should_be_vm_thread */);
1676
1677 verify_region_sets_optional();
1678
1679 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1680 ergo_verbose1(ErgoHeapSizing,
1681 "attempt heap expansion",
1682 ergo_format_reason("allocation request failed")
1683 ergo_format_byte("allocation request"),
1684 word_size * HeapWordSize);
1685 if (expand(expand_bytes)) {
1686 _hrm.verify_optional();
1687 verify_region_sets_optional();
1688 return attempt_allocation_at_safepoint(word_size,
1689 context,
1690 false /* expect_null_mutator_alloc_region */);
1691 }
1692 return NULL;
1693 }
1694
1695 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1696 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1697 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1698 HeapRegion::GrainBytes);
1699 ergo_verbose2(ErgoHeapSizing,
1700 "expand the heap",
1701 ergo_format_byte("requested expansion amount")
1702 ergo_format_byte("attempted expansion amount"),
1703 expand_bytes, aligned_expand_bytes);
1704
1705 if (is_maximal_no_gc()) {
1706 ergo_verbose0(ErgoHeapSizing,
1707 "did not expand the heap",
1708 ergo_format_reason("heap already fully expanded"));
1709 return false;
1710 }
1711
1712 double expand_heap_start_time_sec = os::elapsedTime();
1713 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1714 assert(regions_to_expand > 0, "Must expand by at least one region");
1715
1716 uint expanded_by = _hrm.expand_by(regions_to_expand);
1717 if (expand_time_ms != NULL) {
1718 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1719 }
1720
1721 if (expanded_by > 0) {
1722 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1723 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1724 g1_policy()->record_new_heap_size(num_regions());
1725 } else {
1726 ergo_verbose0(ErgoHeapSizing,
1727 "did not expand the heap",
1728 ergo_format_reason("heap expansion operation failed"));
1729 // The expansion of the virtual storage space was unsuccessful.
1730 // Let's see if it was because we ran out of swap.
1731 if (G1ExitOnExpansionFailure &&
1732 _hrm.available() >= regions_to_expand) {
1733 // We had head room...
1734 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1735 }
1736 }
1737 return regions_to_expand > 0;
1738 }
1739
1740 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1741 size_t aligned_shrink_bytes =
1742 ReservedSpace::page_align_size_down(shrink_bytes);
1743 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1744 HeapRegion::GrainBytes);
1745 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1746
1747 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1748 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1749
1750 ergo_verbose3(ErgoHeapSizing,
1751 "shrink the heap",
1752 ergo_format_byte("requested shrinking amount")
1753 ergo_format_byte("aligned shrinking amount")
1754 ergo_format_byte("attempted shrinking amount"),
1755 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1756 if (num_regions_removed > 0) {
1757 g1_policy()->record_new_heap_size(num_regions());
1758 } else {
1759 ergo_verbose0(ErgoHeapSizing,
1760 "did not shrink the heap",
1761 ergo_format_reason("heap shrinking operation failed"));
1762 }
1763 }
1764
1765 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1766 verify_region_sets_optional();
1767
1768 // We should only reach here at the end of a Full GC which means we
1769 // should not not be holding to any GC alloc regions. The method
1770 // below will make sure of that and do any remaining clean up.
1771 _allocator->abandon_gc_alloc_regions();
1772
1773 // Instead of tearing down / rebuilding the free lists here, we
1774 // could instead use the remove_all_pending() method on free_list to
1775 // remove only the ones that we need to remove.
1776 tear_down_region_sets(true /* free_list_only */);
1777 shrink_helper(shrink_bytes);
1778 rebuild_region_sets(true /* free_list_only */);
1779
1780 _hrm.verify_optional();
1781 verify_region_sets_optional();
1782 }
1783
1784 // Public methods.
1785
1786 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1787 CollectedHeap(),
1788 _g1_policy(policy_),
1789 _dirty_card_queue_set(false),
1790 _is_alive_closure_cm(this),
1791 _is_alive_closure_stw(this),
1792 _ref_processor_cm(NULL),
1793 _ref_processor_stw(NULL),
1794 _bot_shared(NULL),
1795 _cg1r(NULL),
1796 _g1mm(NULL),
1797 _refine_cte_cl(NULL),
1798 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1799 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1800 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1801 _humongous_reclaim_candidates(),
1802 _has_humongous_reclaim_candidates(false),
1803 _archive_allocator(NULL),
1804 _free_regions_coming(false),
1805 _young_list(new YoungList(this)),
1806 _gc_time_stamp(0),
1807 _summary_bytes_used(0),
1808 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1809 _old_evac_stats(OldPLABSize, PLABWeight),
1810 _expand_heap_after_alloc_failure(true),
1811 _old_marking_cycles_started(0),
1812 _old_marking_cycles_completed(0),
1813 _heap_summary_sent(false),
1814 _in_cset_fast_test(),
1815 _dirty_cards_region_list(NULL),
1816 _worker_cset_start_region(NULL),
1817 _worker_cset_start_region_time_stamp(NULL),
1818 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1819 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1820 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1821 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1822
1823 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1824 /* are_GC_task_threads */true,
1825 /* are_ConcurrentGC_threads */false);
1826 _workers->initialize_workers();
1827
1828 _allocator = G1Allocator::create_allocator(this);
1829 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1830
1831 // Override the default _filler_array_max_size so that no humongous filler
1832 // objects are created.
1833 _filler_array_max_size = _humongous_object_threshold_in_words;
1834
1835 uint n_queues = ParallelGCThreads;
1836 _task_queues = new RefToScanQueueSet(n_queues);
1837
1838 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1839 assert(n_rem_sets > 0, "Invariant.");
1840
1841 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1842 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1843 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1844
1845 for (uint i = 0; i < n_queues; i++) {
1846 RefToScanQueue* q = new RefToScanQueue();
1847 q->initialize();
1848 _task_queues->register_queue(i, q);
1849 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1850 }
1851 clear_cset_start_regions();
1852
1853 // Initialize the G1EvacuationFailureALot counters and flags.
1854 NOT_PRODUCT(reset_evacuation_should_fail();)
1855
1856 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1857 }
1858
1859 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1860 size_t size,
1861 size_t translation_factor) {
1862 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1863 // Allocate a new reserved space, preferring to use large pages.
1864 ReservedSpace rs(size, preferred_page_size);
1865 G1RegionToSpaceMapper* result =
1866 G1RegionToSpaceMapper::create_mapper(rs,
1867 size,
1868 rs.alignment(),
1869 HeapRegion::GrainBytes,
1870 translation_factor,
1871 mtGC);
1872 if (TracePageSizes) {
1873 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1874 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1875 }
1876 return result;
1877 }
1878
1879 jint G1CollectedHeap::initialize() {
1880 CollectedHeap::pre_initialize();
1881 os::enable_vtime();
1882
1883 G1Log::init();
1884
1885 // Necessary to satisfy locking discipline assertions.
1886
1887 MutexLocker x(Heap_lock);
1888
1889 // We have to initialize the printer before committing the heap, as
1890 // it will be used then.
1891 _hr_printer.set_active(G1PrintHeapRegions);
1892
1893 // While there are no constraints in the GC code that HeapWordSize
1894 // be any particular value, there are multiple other areas in the
1895 // system which believe this to be true (e.g. oop->object_size in some
1896 // cases incorrectly returns the size in wordSize units rather than
1897 // HeapWordSize).
1898 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1899
1900 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1901 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1902 size_t heap_alignment = collector_policy()->heap_alignment();
1903
1904 // Ensure that the sizes are properly aligned.
1905 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1906 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1907 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1908
1909 _refine_cte_cl = new RefineCardTableEntryClosure();
1910
1911 jint ecode = JNI_OK;
1912 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1913 if (_cg1r == NULL) {
1914 return ecode;
1915 }
1916
1917 // Reserve the maximum.
1918
1919 // When compressed oops are enabled, the preferred heap base
1920 // is calculated by subtracting the requested size from the
1921 // 32Gb boundary and using the result as the base address for
1922 // heap reservation. If the requested size is not aligned to
1923 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1924 // into the ReservedHeapSpace constructor) then the actual
1925 // base of the reserved heap may end up differing from the
1926 // address that was requested (i.e. the preferred heap base).
1927 // If this happens then we could end up using a non-optimal
1928 // compressed oops mode.
1929
1930 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1931 heap_alignment);
1932
1933 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1934
1935 // Create the barrier set for the entire reserved region.
1936 G1SATBCardTableLoggingModRefBS* bs
1937 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1938 bs->initialize();
1939 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1940 set_barrier_set(bs);
1941
1942 // Also create a G1 rem set.
1943 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1944
1945 // Carve out the G1 part of the heap.
1946
1947 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1948 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1949 G1RegionToSpaceMapper* heap_storage =
1950 G1RegionToSpaceMapper::create_mapper(g1_rs,
1951 g1_rs.size(),
1952 page_size,
1953 HeapRegion::GrainBytes,
1954 1,
1955 mtJavaHeap);
1956 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1957 max_byte_size, page_size,
1958 heap_rs.base(),
1959 heap_rs.size());
1960 heap_storage->set_mapping_changed_listener(&_listener);
1961
1962 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1963 G1RegionToSpaceMapper* bot_storage =
1964 create_aux_memory_mapper("Block offset table",
1965 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1966 G1BlockOffsetSharedArray::heap_map_factor());
1967
1968 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1969 G1RegionToSpaceMapper* cardtable_storage =
1970 create_aux_memory_mapper("Card table",
1971 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1972 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1973
1974 G1RegionToSpaceMapper* card_counts_storage =
1975 create_aux_memory_mapper("Card counts table",
1976 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1977 G1CardCounts::heap_map_factor());
1978
1979 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1980 G1RegionToSpaceMapper* prev_bitmap_storage =
1981 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1982 G1RegionToSpaceMapper* next_bitmap_storage =
1983 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1984
1985 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1986 g1_barrier_set()->initialize(cardtable_storage);
1987 // Do later initialization work for concurrent refinement.
1988 _cg1r->init(card_counts_storage);
1989
1990 // 6843694 - ensure that the maximum region index can fit
1991 // in the remembered set structures.
1992 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1993 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1994
1995 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1996 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1997 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1998 "too many cards per region");
1999
2000 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2001
2002 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2003
2004 {
2005 HeapWord* start = _hrm.reserved().start();
2006 HeapWord* end = _hrm.reserved().end();
2007 size_t granularity = HeapRegion::GrainBytes;
2008
2009 _in_cset_fast_test.initialize(start, end, granularity);
2010 _humongous_reclaim_candidates.initialize(start, end, granularity);
2011 }
2012
2013 // Create the ConcurrentMark data structure and thread.
2014 // (Must do this late, so that "max_regions" is defined.)
2015 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2016 if (_cm == NULL || !_cm->completed_initialization()) {
2017 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2018 return JNI_ENOMEM;
2019 }
2020 _cmThread = _cm->cmThread();
2021
2022 // Initialize the from_card cache structure of HeapRegionRemSet.
2023 HeapRegionRemSet::init_heap(max_regions());
2024
2025 // Now expand into the initial heap size.
2026 if (!expand(init_byte_size)) {
2027 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2028 return JNI_ENOMEM;
2029 }
2030
2031 // Perform any initialization actions delegated to the policy.
2032 g1_policy()->init();
2033
2034 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2035 SATB_Q_FL_lock,
2036 G1SATBProcessCompletedThreshold,
2037 Shared_SATB_Q_lock);
2038
2039 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2040 DirtyCardQ_CBL_mon,
2041 DirtyCardQ_FL_lock,
2042 concurrent_g1_refine()->yellow_zone(),
2043 concurrent_g1_refine()->red_zone(),
2044 Shared_DirtyCardQ_lock);
2045
2046 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2047 DirtyCardQ_CBL_mon,
2048 DirtyCardQ_FL_lock,
2049 -1, // never trigger processing
2050 -1, // no limit on length
2051 Shared_DirtyCardQ_lock,
2052 &JavaThread::dirty_card_queue_set());
2053
2054 // Here we allocate the dummy HeapRegion that is required by the
2055 // G1AllocRegion class.
2056 HeapRegion* dummy_region = _hrm.get_dummy_region();
2057
2058 // We'll re-use the same region whether the alloc region will
2059 // require BOT updates or not and, if it doesn't, then a non-young
2060 // region will complain that it cannot support allocations without
2061 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2062 dummy_region->set_eden();
2063 // Make sure it's full.
2064 dummy_region->set_top(dummy_region->end());
2065 G1AllocRegion::setup(this, dummy_region);
2066
2067 _allocator->init_mutator_alloc_region();
2068
2069 // Do create of the monitoring and management support so that
2070 // values in the heap have been properly initialized.
2071 _g1mm = new G1MonitoringSupport(this);
2072
2073 G1StringDedup::initialize();
2074
2075 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2076 for (uint i = 0; i < ParallelGCThreads; i++) {
2077 new (&_preserved_objs[i]) OopAndMarkOopStack();
2078 }
2079
2080 return JNI_OK;
2081 }
2082
2083 void G1CollectedHeap::stop() {
2084 // Stop all concurrent threads. We do this to make sure these threads
2085 // do not continue to execute and access resources (e.g. gclog_or_tty)
2086 // that are destroyed during shutdown.
2087 _cg1r->stop();
2088 _cmThread->stop();
2089 if (G1StringDedup::is_enabled()) {
2090 G1StringDedup::stop();
2091 }
2092 }
2093
2094 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2095 return HeapRegion::max_region_size();
2096 }
2097
2098 void G1CollectedHeap::post_initialize() {
2099 CollectedHeap::post_initialize();
2100 ref_processing_init();
2101 }
2102
2103 void G1CollectedHeap::ref_processing_init() {
2104 // Reference processing in G1 currently works as follows:
2105 //
2106 // * There are two reference processor instances. One is
2107 // used to record and process discovered references
2108 // during concurrent marking; the other is used to
2109 // record and process references during STW pauses
2110 // (both full and incremental).
2111 // * Both ref processors need to 'span' the entire heap as
2112 // the regions in the collection set may be dotted around.
2113 //
2114 // * For the concurrent marking ref processor:
2115 // * Reference discovery is enabled at initial marking.
2116 // * Reference discovery is disabled and the discovered
2117 // references processed etc during remarking.
2118 // * Reference discovery is MT (see below).
2119 // * Reference discovery requires a barrier (see below).
2120 // * Reference processing may or may not be MT
2121 // (depending on the value of ParallelRefProcEnabled
2122 // and ParallelGCThreads).
2123 // * A full GC disables reference discovery by the CM
2124 // ref processor and abandons any entries on it's
2125 // discovered lists.
2126 //
2127 // * For the STW processor:
2128 // * Non MT discovery is enabled at the start of a full GC.
2129 // * Processing and enqueueing during a full GC is non-MT.
2130 // * During a full GC, references are processed after marking.
2131 //
2132 // * Discovery (may or may not be MT) is enabled at the start
2133 // of an incremental evacuation pause.
2134 // * References are processed near the end of a STW evacuation pause.
2135 // * For both types of GC:
2136 // * Discovery is atomic - i.e. not concurrent.
2137 // * Reference discovery will not need a barrier.
2138
2139 MemRegion mr = reserved_region();
2140
2141 // Concurrent Mark ref processor
2142 _ref_processor_cm =
2143 new ReferenceProcessor(mr, // span
2144 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2145 // mt processing
2146 ParallelGCThreads,
2147 // degree of mt processing
2148 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2149 // mt discovery
2150 MAX2(ParallelGCThreads, ConcGCThreads),
2151 // degree of mt discovery
2152 false,
2153 // Reference discovery is not atomic
2154 &_is_alive_closure_cm);
2155 // is alive closure
2156 // (for efficiency/performance)
2157
2158 // STW ref processor
2159 _ref_processor_stw =
2160 new ReferenceProcessor(mr, // span
2161 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2162 // mt processing
2163 ParallelGCThreads,
2164 // degree of mt processing
2165 (ParallelGCThreads > 1),
2166 // mt discovery
2167 ParallelGCThreads,
2168 // degree of mt discovery
2169 true,
2170 // Reference discovery is atomic
2171 &_is_alive_closure_stw);
2172 // is alive closure
2173 // (for efficiency/performance)
2174 }
2175
2176 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2177 return g1_policy();
2178 }
2179
2180 size_t G1CollectedHeap::capacity() const {
2181 return _hrm.length() * HeapRegion::GrainBytes;
2182 }
2183
2184 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2185 hr->reset_gc_time_stamp();
2186 }
2187
2188 #ifndef PRODUCT
2189
2190 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2191 private:
2192 unsigned _gc_time_stamp;
2193 bool _failures;
2194
2195 public:
2196 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2197 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2198
2199 virtual bool doHeapRegion(HeapRegion* hr) {
2200 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2201 if (_gc_time_stamp != region_gc_time_stamp) {
2202 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2203 "expected %d", HR_FORMAT_PARAMS(hr),
2204 region_gc_time_stamp, _gc_time_stamp);
2205 _failures = true;
2206 }
2207 return false;
2208 }
2209
2210 bool failures() { return _failures; }
2211 };
2212
2213 void G1CollectedHeap::check_gc_time_stamps() {
2214 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2215 heap_region_iterate(&cl);
2216 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2217 }
2218 #endif // PRODUCT
2219
2220 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2221 _cg1r->hot_card_cache()->drain(cl, worker_i);
2222 }
2223
2224 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2225 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2226 size_t n_completed_buffers = 0;
2227 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2228 n_completed_buffers++;
2229 }
2230 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2231 dcqs.clear_n_completed_buffers();
2232 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2233 }
2234
2235 // Computes the sum of the storage used by the various regions.
2236 size_t G1CollectedHeap::used() const {
2237 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2238 if (_archive_allocator != NULL) {
2239 result += _archive_allocator->used();
2240 }
2241 return result;
2242 }
2243
2244 size_t G1CollectedHeap::used_unlocked() const {
2245 return _summary_bytes_used;
2246 }
2247
2248 class SumUsedClosure: public HeapRegionClosure {
2249 size_t _used;
2250 public:
2251 SumUsedClosure() : _used(0) {}
2252 bool doHeapRegion(HeapRegion* r) {
2253 _used += r->used();
2254 return false;
2255 }
2256 size_t result() { return _used; }
2257 };
2258
2259 size_t G1CollectedHeap::recalculate_used() const {
2260 double recalculate_used_start = os::elapsedTime();
2261
2262 SumUsedClosure blk;
2263 heap_region_iterate(&blk);
2264
2265 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2266 return blk.result();
2267 }
2268
2269 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2270 switch (cause) {
2271 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2272 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2273 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2274 case GCCause::_g1_humongous_allocation: return true;
2275 case GCCause::_update_allocation_context_stats_inc: return true;
2276 case GCCause::_wb_conc_mark: return true;
2277 default: return false;
2278 }
2279 }
2280
2281 #ifndef PRODUCT
2282 void G1CollectedHeap::allocate_dummy_regions() {
2283 // Let's fill up most of the region
2284 size_t word_size = HeapRegion::GrainWords - 1024;
2285 // And as a result the region we'll allocate will be humongous.
2286 guarantee(is_humongous(word_size), "sanity");
2287
2288 // _filler_array_max_size is set to humongous object threshold
2289 // but temporarily change it to use CollectedHeap::fill_with_object().
2290 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2291
2292 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2293 // Let's use the existing mechanism for the allocation
2294 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2295 AllocationContext::system());
2296 if (dummy_obj != NULL) {
2297 MemRegion mr(dummy_obj, word_size);
2298 CollectedHeap::fill_with_object(mr);
2299 } else {
2300 // If we can't allocate once, we probably cannot allocate
2301 // again. Let's get out of the loop.
2302 break;
2303 }
2304 }
2305 }
2306 #endif // !PRODUCT
2307
2308 void G1CollectedHeap::increment_old_marking_cycles_started() {
2309 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2310 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2311 "Wrong marking cycle count (started: %d, completed: %d)",
2312 _old_marking_cycles_started, _old_marking_cycles_completed);
2313
2314 _old_marking_cycles_started++;
2315 }
2316
2317 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2318 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2319
2320 // We assume that if concurrent == true, then the caller is a
2321 // concurrent thread that was joined the Suspendible Thread
2322 // Set. If there's ever a cheap way to check this, we should add an
2323 // assert here.
2324
2325 // Given that this method is called at the end of a Full GC or of a
2326 // concurrent cycle, and those can be nested (i.e., a Full GC can
2327 // interrupt a concurrent cycle), the number of full collections
2328 // completed should be either one (in the case where there was no
2329 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2330 // behind the number of full collections started.
2331
2332 // This is the case for the inner caller, i.e. a Full GC.
2333 assert(concurrent ||
2334 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2335 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2336 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2337 "is inconsistent with _old_marking_cycles_completed = %u",
2338 _old_marking_cycles_started, _old_marking_cycles_completed);
2339
2340 // This is the case for the outer caller, i.e. the concurrent cycle.
2341 assert(!concurrent ||
2342 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2343 "for outer caller (concurrent cycle): "
2344 "_old_marking_cycles_started = %u "
2345 "is inconsistent with _old_marking_cycles_completed = %u",
2346 _old_marking_cycles_started, _old_marking_cycles_completed);
2347
2348 _old_marking_cycles_completed += 1;
2349
2350 // We need to clear the "in_progress" flag in the CM thread before
2351 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2352 // is set) so that if a waiter requests another System.gc() it doesn't
2353 // incorrectly see that a marking cycle is still in progress.
2354 if (concurrent) {
2355 _cmThread->set_idle();
2356 }
2357
2358 // This notify_all() will ensure that a thread that called
2359 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2360 // and it's waiting for a full GC to finish will be woken up. It is
2361 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2362 FullGCCount_lock->notify_all();
2363 }
2364
2365 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2366 GCIdMarkAndRestore conc_gc_id_mark;
2367 collector_state()->set_concurrent_cycle_started(true);
2368 _gc_timer_cm->register_gc_start(start_time);
2369
2370 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2371 trace_heap_before_gc(_gc_tracer_cm);
2372 _cmThread->set_gc_id(GCId::current());
2373 }
2374
2375 void G1CollectedHeap::register_concurrent_cycle_end() {
2376 if (collector_state()->concurrent_cycle_started()) {
2377 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2378 if (_cm->has_aborted()) {
2379 _gc_tracer_cm->report_concurrent_mode_failure();
2380 }
2381
2382 _gc_timer_cm->register_gc_end();
2383 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2384
2385 // Clear state variables to prepare for the next concurrent cycle.
2386 collector_state()->set_concurrent_cycle_started(false);
2387 _heap_summary_sent = false;
2388 }
2389 }
2390
2391 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2392 if (collector_state()->concurrent_cycle_started()) {
2393 // This function can be called when:
2394 // the cleanup pause is run
2395 // the concurrent cycle is aborted before the cleanup pause.
2396 // the concurrent cycle is aborted after the cleanup pause,
2397 // but before the concurrent cycle end has been registered.
2398 // Make sure that we only send the heap information once.
2399 if (!_heap_summary_sent) {
2400 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2401 trace_heap_after_gc(_gc_tracer_cm);
2402 _heap_summary_sent = true;
2403 }
2404 }
2405 }
2406
2407 void G1CollectedHeap::collect(GCCause::Cause cause) {
2408 assert_heap_not_locked();
2409
2410 uint gc_count_before;
2411 uint old_marking_count_before;
2412 uint full_gc_count_before;
2413 bool retry_gc;
2414
2415 do {
2416 retry_gc = false;
2417
2418 {
2419 MutexLocker ml(Heap_lock);
2420
2421 // Read the GC count while holding the Heap_lock
2422 gc_count_before = total_collections();
2423 full_gc_count_before = total_full_collections();
2424 old_marking_count_before = _old_marking_cycles_started;
2425 }
2426
2427 if (should_do_concurrent_full_gc(cause)) {
2428 // Schedule an initial-mark evacuation pause that will start a
2429 // concurrent cycle. We're setting word_size to 0 which means that
2430 // we are not requesting a post-GC allocation.
2431 VM_G1IncCollectionPause op(gc_count_before,
2432 0, /* word_size */
2433 true, /* should_initiate_conc_mark */
2434 g1_policy()->max_pause_time_ms(),
2435 cause);
2436 op.set_allocation_context(AllocationContext::current());
2437
2438 VMThread::execute(&op);
2439 if (!op.pause_succeeded()) {
2440 if (old_marking_count_before == _old_marking_cycles_started) {
2441 retry_gc = op.should_retry_gc();
2442 } else {
2443 // A Full GC happened while we were trying to schedule the
2444 // initial-mark GC. No point in starting a new cycle given
2445 // that the whole heap was collected anyway.
2446 }
2447
2448 if (retry_gc) {
2449 if (GC_locker::is_active_and_needs_gc()) {
2450 GC_locker::stall_until_clear();
2451 }
2452 }
2453 }
2454 } else {
2455 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2456 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2457
2458 // Schedule a standard evacuation pause. We're setting word_size
2459 // to 0 which means that we are not requesting a post-GC allocation.
2460 VM_G1IncCollectionPause op(gc_count_before,
2461 0, /* word_size */
2462 false, /* should_initiate_conc_mark */
2463 g1_policy()->max_pause_time_ms(),
2464 cause);
2465 VMThread::execute(&op);
2466 } else {
2467 // Schedule a Full GC.
2468 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2469 VMThread::execute(&op);
2470 }
2471 }
2472 } while (retry_gc);
2473 }
2474
2475 bool G1CollectedHeap::is_in(const void* p) const {
2476 if (_hrm.reserved().contains(p)) {
2477 // Given that we know that p is in the reserved space,
2478 // heap_region_containing() should successfully
2479 // return the containing region.
2480 HeapRegion* hr = heap_region_containing(p);
2481 return hr->is_in(p);
2482 } else {
2483 return false;
2484 }
2485 }
2486
2487 #ifdef ASSERT
2488 bool G1CollectedHeap::is_in_exact(const void* p) const {
2489 bool contains = reserved_region().contains(p);
2490 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2491 if (contains && available) {
2492 return true;
2493 } else {
2494 return false;
2495 }
2496 }
2497 #endif
2498
2499 bool G1CollectedHeap::obj_in_cs(oop obj) {
2500 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2501 return r != NULL && r->in_collection_set();
2502 }
2503
2504 // Iteration functions.
2505
2506 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2507
2508 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2509 ExtendedOopClosure* _cl;
2510 public:
2511 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2512 bool doHeapRegion(HeapRegion* r) {
2513 if (!r->is_continues_humongous()) {
2514 r->oop_iterate(_cl);
2515 }
2516 return false;
2517 }
2518 };
2519
2520 // Iterates an ObjectClosure over all objects within a HeapRegion.
2521
2522 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2523 ObjectClosure* _cl;
2524 public:
2525 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2526 bool doHeapRegion(HeapRegion* r) {
2527 if (!r->is_continues_humongous()) {
2528 r->object_iterate(_cl);
2529 }
2530 return false;
2531 }
2532 };
2533
2534 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2535 IterateObjectClosureRegionClosure blk(cl);
2536 heap_region_iterate(&blk);
2537 }
2538
2539 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2540 _hrm.iterate(cl);
2541 }
2542
2543 void
2544 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2545 uint worker_id,
2546 HeapRegionClaimer *hrclaimer,
2547 bool concurrent) const {
2548 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2549 }
2550
2551 // Clear the cached CSet starting regions and (more importantly)
2552 // the time stamps. Called when we reset the GC time stamp.
2553 void G1CollectedHeap::clear_cset_start_regions() {
2554 assert(_worker_cset_start_region != NULL, "sanity");
2555 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2556
2557 for (uint i = 0; i < ParallelGCThreads; i++) {
2558 _worker_cset_start_region[i] = NULL;
2559 _worker_cset_start_region_time_stamp[i] = 0;
2560 }
2561 }
2562
2563 // Given the id of a worker, obtain or calculate a suitable
2564 // starting region for iterating over the current collection set.
2565 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2566 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2567
2568 HeapRegion* result = NULL;
2569 unsigned gc_time_stamp = get_gc_time_stamp();
2570
2571 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2572 // Cached starting region for current worker was set
2573 // during the current pause - so it's valid.
2574 // Note: the cached starting heap region may be NULL
2575 // (when the collection set is empty).
2576 result = _worker_cset_start_region[worker_i];
2577 assert(result == NULL || result->in_collection_set(), "sanity");
2578 return result;
2579 }
2580
2581 // The cached entry was not valid so let's calculate
2582 // a suitable starting heap region for this worker.
2583
2584 // We want the parallel threads to start their collection
2585 // set iteration at different collection set regions to
2586 // avoid contention.
2587 // If we have:
2588 // n collection set regions
2589 // p threads
2590 // Then thread t will start at region floor ((t * n) / p)
2591
2592 result = g1_policy()->collection_set();
2593 uint cs_size = g1_policy()->cset_region_length();
2594 uint active_workers = workers()->active_workers();
2595
2596 uint end_ind = (cs_size * worker_i) / active_workers;
2597 uint start_ind = 0;
2598
2599 if (worker_i > 0 &&
2600 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2601 // Previous workers starting region is valid
2602 // so let's iterate from there
2603 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2604 result = _worker_cset_start_region[worker_i - 1];
2605 }
2606
2607 for (uint i = start_ind; i < end_ind; i++) {
2608 result = result->next_in_collection_set();
2609 }
2610
2611 // Note: the calculated starting heap region may be NULL
2612 // (when the collection set is empty).
2613 assert(result == NULL || result->in_collection_set(), "sanity");
2614 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2615 "should be updated only once per pause");
2616 _worker_cset_start_region[worker_i] = result;
2617 OrderAccess::storestore();
2618 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2619 return result;
2620 }
2621
2622 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2623 HeapRegion* r = g1_policy()->collection_set();
2624 while (r != NULL) {
2625 HeapRegion* next = r->next_in_collection_set();
2626 if (cl->doHeapRegion(r)) {
2627 cl->incomplete();
2628 return;
2629 }
2630 r = next;
2631 }
2632 }
2633
2634 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2635 HeapRegionClosure *cl) {
2636 if (r == NULL) {
2637 // The CSet is empty so there's nothing to do.
2638 return;
2639 }
2640
2641 assert(r->in_collection_set(),
2642 "Start region must be a member of the collection set.");
2643 HeapRegion* cur = r;
2644 while (cur != NULL) {
2645 HeapRegion* next = cur->next_in_collection_set();
2646 if (cl->doHeapRegion(cur) && false) {
2647 cl->incomplete();
2648 return;
2649 }
2650 cur = next;
2651 }
2652 cur = g1_policy()->collection_set();
2653 while (cur != r) {
2654 HeapRegion* next = cur->next_in_collection_set();
2655 if (cl->doHeapRegion(cur) && false) {
2656 cl->incomplete();
2657 return;
2658 }
2659 cur = next;
2660 }
2661 }
2662
2663 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2664 HeapRegion* result = _hrm.next_region_in_heap(from);
2665 while (result != NULL && result->is_pinned()) {
2666 result = _hrm.next_region_in_heap(result);
2667 }
2668 return result;
2669 }
2670
2671 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2672 HeapRegion* hr = heap_region_containing(addr);
2673 return hr->block_start(addr);
2674 }
2675
2676 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2677 HeapRegion* hr = heap_region_containing(addr);
2678 return hr->block_size(addr);
2679 }
2680
2681 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2682 HeapRegion* hr = heap_region_containing(addr);
2683 return hr->block_is_obj(addr);
2684 }
2685
2686 bool G1CollectedHeap::supports_tlab_allocation() const {
2687 return true;
2688 }
2689
2690 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2691 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2692 }
2693
2694 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2695 return young_list()->eden_used_bytes();
2696 }
2697
2698 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2699 // must be equal to the humongous object limit.
2700 size_t G1CollectedHeap::max_tlab_size() const {
2701 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2702 }
2703
2704 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2705 AllocationContext_t context = AllocationContext::current();
2706 return _allocator->unsafe_max_tlab_alloc(context);
2707 }
2708
2709 size_t G1CollectedHeap::max_capacity() const {
2710 return _hrm.reserved().byte_size();
2711 }
2712
2713 jlong G1CollectedHeap::millis_since_last_gc() {
2714 // assert(false, "NYI");
2715 return 0;
2716 }
2717
2718 void G1CollectedHeap::prepare_for_verify() {
2719 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2720 ensure_parsability(false);
2721 }
2722 g1_rem_set()->prepare_for_verify();
2723 }
2724
2725 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2726 VerifyOption vo) {
2727 switch (vo) {
2728 case VerifyOption_G1UsePrevMarking:
2729 return hr->obj_allocated_since_prev_marking(obj);
2730 case VerifyOption_G1UseNextMarking:
2731 return hr->obj_allocated_since_next_marking(obj);
2732 case VerifyOption_G1UseMarkWord:
2733 return false;
2734 default:
2735 ShouldNotReachHere();
2736 }
2737 return false; // keep some compilers happy
2738 }
2739
2740 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2741 switch (vo) {
2742 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2743 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2744 case VerifyOption_G1UseMarkWord: return NULL;
2745 default: ShouldNotReachHere();
2746 }
2747 return NULL; // keep some compilers happy
2748 }
2749
2750 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2751 switch (vo) {
2752 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2753 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2754 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2755 default: ShouldNotReachHere();
2756 }
2757 return false; // keep some compilers happy
2758 }
2759
2760 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2761 switch (vo) {
2762 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2763 case VerifyOption_G1UseNextMarking: return "NTAMS";
2764 case VerifyOption_G1UseMarkWord: return "NONE";
2765 default: ShouldNotReachHere();
2766 }
2767 return NULL; // keep some compilers happy
2768 }
2769
2770 class VerifyRootsClosure: public OopClosure {
2771 private:
2772 G1CollectedHeap* _g1h;
2773 VerifyOption _vo;
2774 bool _failures;
2775 public:
2776 // _vo == UsePrevMarking -> use "prev" marking information,
2777 // _vo == UseNextMarking -> use "next" marking information,
2778 // _vo == UseMarkWord -> use mark word from object header.
2779 VerifyRootsClosure(VerifyOption vo) :
2780 _g1h(G1CollectedHeap::heap()),
2781 _vo(vo),
2782 _failures(false) { }
2783
2784 bool failures() { return _failures; }
2785
2786 template <class T> void do_oop_nv(T* p) {
2787 T heap_oop = oopDesc::load_heap_oop(p);
2788 if (!oopDesc::is_null(heap_oop)) {
2789 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2790 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2791 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2792 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2793 if (_vo == VerifyOption_G1UseMarkWord) {
2794 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2795 }
2796 obj->print_on(gclog_or_tty);
2797 _failures = true;
2798 }
2799 }
2800 }
2801
2802 void do_oop(oop* p) { do_oop_nv(p); }
2803 void do_oop(narrowOop* p) { do_oop_nv(p); }
2804 };
2805
2806 class G1VerifyCodeRootOopClosure: public OopClosure {
2807 G1CollectedHeap* _g1h;
2808 OopClosure* _root_cl;
2809 nmethod* _nm;
2810 VerifyOption _vo;
2811 bool _failures;
2812
2813 template <class T> void do_oop_work(T* p) {
2814 // First verify that this root is live
2815 _root_cl->do_oop(p);
2816
2817 if (!G1VerifyHeapRegionCodeRoots) {
2818 // We're not verifying the code roots attached to heap region.
2819 return;
2820 }
2821
2822 // Don't check the code roots during marking verification in a full GC
2823 if (_vo == VerifyOption_G1UseMarkWord) {
2824 return;
2825 }
2826
2827 // Now verify that the current nmethod (which contains p) is
2828 // in the code root list of the heap region containing the
2829 // object referenced by p.
2830
2831 T heap_oop = oopDesc::load_heap_oop(p);
2832 if (!oopDesc::is_null(heap_oop)) {
2833 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2834
2835 // Now fetch the region containing the object
2836 HeapRegion* hr = _g1h->heap_region_containing(obj);
2837 HeapRegionRemSet* hrrs = hr->rem_set();
2838 // Verify that the strong code root list for this region
2839 // contains the nmethod
2840 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2841 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2842 "from nmethod " PTR_FORMAT " not in strong "
2843 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2844 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2845 _failures = true;
2846 }
2847 }
2848 }
2849
2850 public:
2851 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2852 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2853
2854 void do_oop(oop* p) { do_oop_work(p); }
2855 void do_oop(narrowOop* p) { do_oop_work(p); }
2856
2857 void set_nmethod(nmethod* nm) { _nm = nm; }
2858 bool failures() { return _failures; }
2859 };
2860
2861 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2862 G1VerifyCodeRootOopClosure* _oop_cl;
2863
2864 public:
2865 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2866 _oop_cl(oop_cl) {}
2867
2868 void do_code_blob(CodeBlob* cb) {
2869 nmethod* nm = cb->as_nmethod_or_null();
2870 if (nm != NULL) {
2871 _oop_cl->set_nmethod(nm);
2872 nm->oops_do(_oop_cl);
2873 }
2874 }
2875 };
2876
2877 class YoungRefCounterClosure : public OopClosure {
2878 G1CollectedHeap* _g1h;
2879 int _count;
2880 public:
2881 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2882 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2883 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2884
2885 int count() { return _count; }
2886 void reset_count() { _count = 0; };
2887 };
2888
2889 class VerifyKlassClosure: public KlassClosure {
2890 YoungRefCounterClosure _young_ref_counter_closure;
2891 OopClosure *_oop_closure;
2892 public:
2893 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2894 void do_klass(Klass* k) {
2895 k->oops_do(_oop_closure);
2896
2897 _young_ref_counter_closure.reset_count();
2898 k->oops_do(&_young_ref_counter_closure);
2899 if (_young_ref_counter_closure.count() > 0) {
2900 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2901 }
2902 }
2903 };
2904
2905 class VerifyLivenessOopClosure: public OopClosure {
2906 G1CollectedHeap* _g1h;
2907 VerifyOption _vo;
2908 public:
2909 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2910 _g1h(g1h), _vo(vo)
2911 { }
2912 void do_oop(narrowOop *p) { do_oop_work(p); }
2913 void do_oop( oop *p) { do_oop_work(p); }
2914
2915 template <class T> void do_oop_work(T *p) {
2916 oop obj = oopDesc::load_decode_heap_oop(p);
2917 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2918 "Dead object referenced by a not dead object");
2919 }
2920 };
2921
2922 class VerifyObjsInRegionClosure: public ObjectClosure {
2923 private:
2924 G1CollectedHeap* _g1h;
2925 size_t _live_bytes;
2926 HeapRegion *_hr;
2927 VerifyOption _vo;
2928 public:
2929 // _vo == UsePrevMarking -> use "prev" marking information,
2930 // _vo == UseNextMarking -> use "next" marking information,
2931 // _vo == UseMarkWord -> use mark word from object header.
2932 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2933 : _live_bytes(0), _hr(hr), _vo(vo) {
2934 _g1h = G1CollectedHeap::heap();
2935 }
2936 void do_object(oop o) {
2937 VerifyLivenessOopClosure isLive(_g1h, _vo);
2938 assert(o != NULL, "Huh?");
2939 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2940 // If the object is alive according to the mark word,
2941 // then verify that the marking information agrees.
2942 // Note we can't verify the contra-positive of the
2943 // above: if the object is dead (according to the mark
2944 // word), it may not be marked, or may have been marked
2945 // but has since became dead, or may have been allocated
2946 // since the last marking.
2947 if (_vo == VerifyOption_G1UseMarkWord) {
2948 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2949 }
2950
2951 o->oop_iterate_no_header(&isLive);
2952 if (!_hr->obj_allocated_since_prev_marking(o)) {
2953 size_t obj_size = o->size(); // Make sure we don't overflow
2954 _live_bytes += (obj_size * HeapWordSize);
2955 }
2956 }
2957 }
2958 size_t live_bytes() { return _live_bytes; }
2959 };
2960
2961 class VerifyArchiveOopClosure: public OopClosure {
2962 public:
2963 VerifyArchiveOopClosure(HeapRegion *hr) { }
2964 void do_oop(narrowOop *p) { do_oop_work(p); }
2965 void do_oop( oop *p) { do_oop_work(p); }
2966
2967 template <class T> void do_oop_work(T *p) {
2968 oop obj = oopDesc::load_decode_heap_oop(p);
2969 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2970 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2971 p2i(p), p2i(obj));
2972 }
2973 };
2974
2975 class VerifyArchiveRegionClosure: public ObjectClosure {
2976 public:
2977 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2978 // Verify that all object pointers are to archive regions.
2979 void do_object(oop o) {
2980 VerifyArchiveOopClosure checkOop(NULL);
2981 assert(o != NULL, "Should not be here for NULL oops");
2982 o->oop_iterate_no_header(&checkOop);
2983 }
2984 };
2985
2986 class VerifyRegionClosure: public HeapRegionClosure {
2987 private:
2988 bool _par;
2989 VerifyOption _vo;
2990 bool _failures;
2991 public:
2992 // _vo == UsePrevMarking -> use "prev" marking information,
2993 // _vo == UseNextMarking -> use "next" marking information,
2994 // _vo == UseMarkWord -> use mark word from object header.
2995 VerifyRegionClosure(bool par, VerifyOption vo)
2996 : _par(par),
2997 _vo(vo),
2998 _failures(false) {}
2999
3000 bool failures() {
3001 return _failures;
3002 }
3003
3004 bool doHeapRegion(HeapRegion* r) {
3005 // For archive regions, verify there are no heap pointers to
3006 // non-pinned regions. For all others, verify liveness info.
3007 if (r->is_archive()) {
3008 VerifyArchiveRegionClosure verify_oop_pointers(r);
3009 r->object_iterate(&verify_oop_pointers);
3010 return true;
3011 }
3012 if (!r->is_continues_humongous()) {
3013 bool failures = false;
3014 r->verify(_vo, &failures);
3015 if (failures) {
3016 _failures = true;
3017 } else if (!r->is_starts_humongous()) {
3018 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3019 r->object_iterate(¬_dead_yet_cl);
3020 if (_vo != VerifyOption_G1UseNextMarking) {
3021 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3022 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3023 "max_live_bytes " SIZE_FORMAT " "
3024 "< calculated " SIZE_FORMAT,
3025 p2i(r->bottom()), p2i(r->end()),
3026 r->max_live_bytes(),
3027 not_dead_yet_cl.live_bytes());
3028 _failures = true;
3029 }
3030 } else {
3031 // When vo == UseNextMarking we cannot currently do a sanity
3032 // check on the live bytes as the calculation has not been
3033 // finalized yet.
3034 }
3035 }
3036 }
3037 return false; // stop the region iteration if we hit a failure
3038 }
3039 };
3040
3041 // This is the task used for parallel verification of the heap regions
3042
3043 class G1ParVerifyTask: public AbstractGangTask {
3044 private:
3045 G1CollectedHeap* _g1h;
3046 VerifyOption _vo;
3047 bool _failures;
3048 HeapRegionClaimer _hrclaimer;
3049
3050 public:
3051 // _vo == UsePrevMarking -> use "prev" marking information,
3052 // _vo == UseNextMarking -> use "next" marking information,
3053 // _vo == UseMarkWord -> use mark word from object header.
3054 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3055 AbstractGangTask("Parallel verify task"),
3056 _g1h(g1h),
3057 _vo(vo),
3058 _failures(false),
3059 _hrclaimer(g1h->workers()->active_workers()) {}
3060
3061 bool failures() {
3062 return _failures;
3063 }
3064
3065 void work(uint worker_id) {
3066 HandleMark hm;
3067 VerifyRegionClosure blk(true, _vo);
3068 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3069 if (blk.failures()) {
3070 _failures = true;
3071 }
3072 }
3073 };
3074
3075 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3076 if (SafepointSynchronize::is_at_safepoint()) {
3077 assert(Thread::current()->is_VM_thread(),
3078 "Expected to be executed serially by the VM thread at this point");
3079
3080 if (!silent) { gclog_or_tty->print("Roots "); }
3081 VerifyRootsClosure rootsCl(vo);
3082 VerifyKlassClosure klassCl(this, &rootsCl);
3083 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3084
3085 // We apply the relevant closures to all the oops in the
3086 // system dictionary, class loader data graph, the string table
3087 // and the nmethods in the code cache.
3088 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3089 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3090
3091 {
3092 G1RootProcessor root_processor(this, 1);
3093 root_processor.process_all_roots(&rootsCl,
3094 &cldCl,
3095 &blobsCl);
3096 }
3097
3098 bool failures = rootsCl.failures() || codeRootsCl.failures();
3099
3100 if (vo != VerifyOption_G1UseMarkWord) {
3101 // If we're verifying during a full GC then the region sets
3102 // will have been torn down at the start of the GC. Therefore
3103 // verifying the region sets will fail. So we only verify
3104 // the region sets when not in a full GC.
3105 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3106 verify_region_sets();
3107 }
3108
3109 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3110 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3111
3112 G1ParVerifyTask task(this, vo);
3113 workers()->run_task(&task);
3114 if (task.failures()) {
3115 failures = true;
3116 }
3117
3118 } else {
3119 VerifyRegionClosure blk(false, vo);
3120 heap_region_iterate(&blk);
3121 if (blk.failures()) {
3122 failures = true;
3123 }
3124 }
3125
3126 if (G1StringDedup::is_enabled()) {
3127 if (!silent) gclog_or_tty->print("StrDedup ");
3128 G1StringDedup::verify();
3129 }
3130
3131 if (failures) {
3132 gclog_or_tty->print_cr("Heap:");
3133 // It helps to have the per-region information in the output to
3134 // help us track down what went wrong. This is why we call
3135 // print_extended_on() instead of print_on().
3136 print_extended_on(gclog_or_tty);
3137 gclog_or_tty->cr();
3138 gclog_or_tty->flush();
3139 }
3140 guarantee(!failures, "there should not have been any failures");
3141 } else {
3142 if (!silent) {
3143 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3144 if (G1StringDedup::is_enabled()) {
3145 gclog_or_tty->print(", StrDedup");
3146 }
3147 gclog_or_tty->print(") ");
3148 }
3149 }
3150 }
3151
3152 void G1CollectedHeap::verify(bool silent) {
3153 verify(silent, VerifyOption_G1UsePrevMarking);
3154 }
3155
3156 double G1CollectedHeap::verify(bool guard, const char* msg) {
3157 double verify_time_ms = 0.0;
3158
3159 if (guard && total_collections() >= VerifyGCStartAt) {
3160 double verify_start = os::elapsedTime();
3161 HandleMark hm; // Discard invalid handles created during verification
3162 prepare_for_verify();
3163 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3164 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3165 }
3166
3167 return verify_time_ms;
3168 }
3169
3170 void G1CollectedHeap::verify_before_gc() {
3171 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3172 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3173 }
3174
3175 void G1CollectedHeap::verify_after_gc() {
3176 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3177 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3178 }
3179
3180 class PrintRegionClosure: public HeapRegionClosure {
3181 outputStream* _st;
3182 public:
3183 PrintRegionClosure(outputStream* st) : _st(st) {}
3184 bool doHeapRegion(HeapRegion* r) {
3185 r->print_on(_st);
3186 return false;
3187 }
3188 };
3189
3190 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3191 const HeapRegion* hr,
3192 const VerifyOption vo) const {
3193 switch (vo) {
3194 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3195 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3196 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3197 default: ShouldNotReachHere();
3198 }
3199 return false; // keep some compilers happy
3200 }
3201
3202 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3203 const VerifyOption vo) const {
3204 switch (vo) {
3205 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3206 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3207 case VerifyOption_G1UseMarkWord: {
3208 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3209 return !obj->is_gc_marked() && !hr->is_archive();
3210 }
3211 default: ShouldNotReachHere();
3212 }
3213 return false; // keep some compilers happy
3214 }
3215
3216 void G1CollectedHeap::print_on(outputStream* st) const {
3217 st->print(" %-20s", "garbage-first heap");
3218 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3219 capacity()/K, used_unlocked()/K);
3220 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3221 p2i(_hrm.reserved().start()),
3222 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3223 p2i(_hrm.reserved().end()));
3224 st->cr();
3225 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3226 uint young_regions = _young_list->length();
3227 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3228 (size_t) young_regions * HeapRegion::GrainBytes / K);
3229 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3230 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3231 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3232 st->cr();
3233 MetaspaceAux::print_on(st);
3234 }
3235
3236 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3237 print_on(st);
3238
3239 // Print the per-region information.
3240 st->cr();
3241 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3242 "HS=humongous(starts), HC=humongous(continues), "
3243 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3244 "PTAMS=previous top-at-mark-start, "
3245 "NTAMS=next top-at-mark-start)");
3246 PrintRegionClosure blk(st);
3247 heap_region_iterate(&blk);
3248 }
3249
3250 void G1CollectedHeap::print_on_error(outputStream* st) const {
3251 this->CollectedHeap::print_on_error(st);
3252
3253 if (_cm != NULL) {
3254 st->cr();
3255 _cm->print_on_error(st);
3256 }
3257 }
3258
3259 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3260 workers()->print_worker_threads_on(st);
3261 _cmThread->print_on(st);
3262 st->cr();
3263 _cm->print_worker_threads_on(st);
3264 _cg1r->print_worker_threads_on(st);
3265 if (G1StringDedup::is_enabled()) {
3266 G1StringDedup::print_worker_threads_on(st);
3267 }
3268 }
3269
3270 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3271 workers()->threads_do(tc);
3272 tc->do_thread(_cmThread);
3273 _cg1r->threads_do(tc);
3274 if (G1StringDedup::is_enabled()) {
3275 G1StringDedup::threads_do(tc);
3276 }
3277 }
3278
3279 void G1CollectedHeap::print_tracing_info() const {
3280 // We'll overload this to mean "trace GC pause statistics."
3281 if (TraceYoungGenTime || TraceOldGenTime) {
3282 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3283 // to that.
3284 g1_policy()->print_tracing_info();
3285 }
3286 if (G1SummarizeRSetStats) {
3287 g1_rem_set()->print_summary_info();
3288 }
3289 if (G1SummarizeConcMark) {
3290 concurrent_mark()->print_summary_info();
3291 }
3292 g1_policy()->print_yg_surv_rate_info();
3293 }
3294
3295 #ifndef PRODUCT
3296 // Helpful for debugging RSet issues.
3297
3298 class PrintRSetsClosure : public HeapRegionClosure {
3299 private:
3300 const char* _msg;
3301 size_t _occupied_sum;
3302
3303 public:
3304 bool doHeapRegion(HeapRegion* r) {
3305 HeapRegionRemSet* hrrs = r->rem_set();
3306 size_t occupied = hrrs->occupied();
3307 _occupied_sum += occupied;
3308
3309 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3310 HR_FORMAT_PARAMS(r));
3311 if (occupied == 0) {
3312 gclog_or_tty->print_cr(" RSet is empty");
3313 } else {
3314 hrrs->print();
3315 }
3316 gclog_or_tty->print_cr("----------");
3317 return false;
3318 }
3319
3320 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3321 gclog_or_tty->cr();
3322 gclog_or_tty->print_cr("========================================");
3323 gclog_or_tty->print_cr("%s", msg);
3324 gclog_or_tty->cr();
3325 }
3326
3327 ~PrintRSetsClosure() {
3328 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3329 gclog_or_tty->print_cr("========================================");
3330 gclog_or_tty->cr();
3331 }
3332 };
3333
3334 void G1CollectedHeap::print_cset_rsets() {
3335 PrintRSetsClosure cl("Printing CSet RSets");
3336 collection_set_iterate(&cl);
3337 }
3338
3339 void G1CollectedHeap::print_all_rsets() {
3340 PrintRSetsClosure cl("Printing All RSets");;
3341 heap_region_iterate(&cl);
3342 }
3343 #endif // PRODUCT
3344
3345 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3346 YoungList* young_list = heap()->young_list();
3347
3348 size_t eden_used_bytes = young_list->eden_used_bytes();
3349 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3350
3351 size_t eden_capacity_bytes =
3352 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3353
3354 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3355 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3356 }
3357
3358 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3359 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3360 stats->unused(), stats->used(), stats->region_end_waste(),
3361 stats->regions_filled(), stats->direct_allocated(),
3362 stats->failure_used(), stats->failure_waste());
3363 }
3364
3365 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3366 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3367 gc_tracer->report_gc_heap_summary(when, heap_summary);
3368
3369 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3370 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3371 }
3372
3373
3374 G1CollectedHeap* G1CollectedHeap::heap() {
3375 CollectedHeap* heap = Universe::heap();
3376 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3377 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3378 return (G1CollectedHeap*)heap;
3379 }
3380
3381 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3382 // always_do_update_barrier = false;
3383 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3384 // Fill TLAB's and such
3385 accumulate_statistics_all_tlabs();
3386 ensure_parsability(true);
3387
3388 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3389 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3390 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3391 }
3392 }
3393
3394 void G1CollectedHeap::gc_epilogue(bool full) {
3395
3396 if (G1SummarizeRSetStats &&
3397 (G1SummarizeRSetStatsPeriod > 0) &&
3398 // we are at the end of the GC. Total collections has already been increased.
3399 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3400 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3401 }
3402
3403 // FIXME: what is this about?
3404 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3405 // is set.
3406 #if defined(COMPILER2) || INCLUDE_JVMCI
3407 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3408 #endif
3409 // always_do_update_barrier = true;
3410
3411 resize_all_tlabs();
3412 allocation_context_stats().update(full);
3413
3414 // We have just completed a GC. Update the soft reference
3415 // policy with the new heap occupancy
3416 Universe::update_heap_info_at_gc();
3417 }
3418
3419 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3420 uint gc_count_before,
3421 bool* succeeded,
3422 GCCause::Cause gc_cause) {
3423 assert_heap_not_locked_and_not_at_safepoint();
3424 g1_policy()->record_stop_world_start();
3425 VM_G1IncCollectionPause op(gc_count_before,
3426 word_size,
3427 false, /* should_initiate_conc_mark */
3428 g1_policy()->max_pause_time_ms(),
3429 gc_cause);
3430
3431 op.set_allocation_context(AllocationContext::current());
3432 VMThread::execute(&op);
3433
3434 HeapWord* result = op.result();
3435 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3436 assert(result == NULL || ret_succeeded,
3437 "the result should be NULL if the VM did not succeed");
3438 *succeeded = ret_succeeded;
3439
3440 assert_heap_not_locked();
3441 return result;
3442 }
3443
3444 void
3445 G1CollectedHeap::doConcurrentMark() {
3446 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3447 if (!_cmThread->in_progress()) {
3448 _cmThread->set_started();
3449 CGC_lock->notify();
3450 }
3451 }
3452
3453 size_t G1CollectedHeap::pending_card_num() {
3454 size_t extra_cards = 0;
3455 JavaThread *curr = Threads::first();
3456 while (curr != NULL) {
3457 DirtyCardQueue& dcq = curr->dirty_card_queue();
3458 extra_cards += dcq.size();
3459 curr = curr->next();
3460 }
3461 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3462 size_t buffer_size = dcqs.buffer_size();
3463 size_t buffer_num = dcqs.completed_buffers_num();
3464
3465 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3466 // in bytes - not the number of 'entries'. We need to convert
3467 // into a number of cards.
3468 return (buffer_size * buffer_num + extra_cards) / oopSize;
3469 }
3470
3471 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3472 private:
3473 size_t _total_humongous;
3474 size_t _candidate_humongous;
3475
3476 DirtyCardQueue _dcq;
3477
3478 // We don't nominate objects with many remembered set entries, on
3479 // the assumption that such objects are likely still live.
3480 bool is_remset_small(HeapRegion* region) const {
3481 HeapRegionRemSet* const rset = region->rem_set();
3482 return G1EagerReclaimHumongousObjectsWithStaleRefs
3483 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3484 : rset->is_empty();
3485 }
3486
3487 bool is_typeArray_region(HeapRegion* region) const {
3488 return oop(region->bottom())->is_typeArray();
3489 }
3490
3491 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3492 assert(region->is_starts_humongous(), "Must start a humongous object");
3493
3494 // Candidate selection must satisfy the following constraints
3495 // while concurrent marking is in progress:
3496 //
3497 // * In order to maintain SATB invariants, an object must not be
3498 // reclaimed if it was allocated before the start of marking and
3499 // has not had its references scanned. Such an object must have
3500 // its references (including type metadata) scanned to ensure no
3501 // live objects are missed by the marking process. Objects
3502 // allocated after the start of concurrent marking don't need to
3503 // be scanned.
3504 //
3505 // * An object must not be reclaimed if it is on the concurrent
3506 // mark stack. Objects allocated after the start of concurrent
3507 // marking are never pushed on the mark stack.
3508 //
3509 // Nominating only objects allocated after the start of concurrent
3510 // marking is sufficient to meet both constraints. This may miss
3511 // some objects that satisfy the constraints, but the marking data
3512 // structures don't support efficiently performing the needed
3513 // additional tests or scrubbing of the mark stack.
3514 //
3515 // However, we presently only nominate is_typeArray() objects.
3516 // A humongous object containing references induces remembered
3517 // set entries on other regions. In order to reclaim such an
3518 // object, those remembered sets would need to be cleaned up.
3519 //
3520 // We also treat is_typeArray() objects specially, allowing them
3521 // to be reclaimed even if allocated before the start of
3522 // concurrent mark. For this we rely on mark stack insertion to
3523 // exclude is_typeArray() objects, preventing reclaiming an object
3524 // that is in the mark stack. We also rely on the metadata for
3525 // such objects to be built-in and so ensured to be kept live.
3526 // Frequent allocation and drop of large binary blobs is an
3527 // important use case for eager reclaim, and this special handling
3528 // may reduce needed headroom.
3529
3530 return is_typeArray_region(region) && is_remset_small(region);
3531 }
3532
3533 public:
3534 RegisterHumongousWithInCSetFastTestClosure()
3535 : _total_humongous(0),
3536 _candidate_humongous(0),
3537 _dcq(&JavaThread::dirty_card_queue_set()) {
3538 }
3539
3540 virtual bool doHeapRegion(HeapRegion* r) {
3541 if (!r->is_starts_humongous()) {
3542 return false;
3543 }
3544 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3545
3546 bool is_candidate = humongous_region_is_candidate(g1h, r);
3547 uint rindex = r->hrm_index();
3548 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3549 if (is_candidate) {
3550 _candidate_humongous++;
3551 g1h->register_humongous_region_with_cset(rindex);
3552 // Is_candidate already filters out humongous object with large remembered sets.
3553 // If we have a humongous object with a few remembered sets, we simply flush these
3554 // remembered set entries into the DCQS. That will result in automatic
3555 // re-evaluation of their remembered set entries during the following evacuation
3556 // phase.
3557 if (!r->rem_set()->is_empty()) {
3558 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3559 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3560 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3561 HeapRegionRemSetIterator hrrs(r->rem_set());
3562 size_t card_index;
3563 while (hrrs.has_next(card_index)) {
3564 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3565 // The remembered set might contain references to already freed
3566 // regions. Filter out such entries to avoid failing card table
3567 // verification.
3568 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3569 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3570 *card_ptr = CardTableModRefBS::dirty_card_val();
3571 _dcq.enqueue(card_ptr);
3572 }
3573 }
3574 }
3575 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3576 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3577 hrrs.n_yielded(), r->rem_set()->occupied());
3578 r->rem_set()->clear_locked();
3579 }
3580 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3581 }
3582 _total_humongous++;
3583
3584 return false;
3585 }
3586
3587 size_t total_humongous() const { return _total_humongous; }
3588 size_t candidate_humongous() const { return _candidate_humongous; }
3589
3590 void flush_rem_set_entries() { _dcq.flush(); }
3591 };
3592
3593 void G1CollectedHeap::register_humongous_regions_with_cset() {
3594 if (!G1EagerReclaimHumongousObjects) {
3595 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3596 return;
3597 }
3598 double time = os::elapsed_counter();
3599
3600 // Collect reclaim candidate information and register candidates with cset.
3601 RegisterHumongousWithInCSetFastTestClosure cl;
3602 heap_region_iterate(&cl);
3603
3604 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3605 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3606 cl.total_humongous(),
3607 cl.candidate_humongous());
3608 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3609
3610 // Finally flush all remembered set entries to re-check into the global DCQS.
3611 cl.flush_rem_set_entries();
3612 }
3613
3614 #ifdef ASSERT
3615 class VerifyCSetClosure: public HeapRegionClosure {
3616 public:
3617 bool doHeapRegion(HeapRegion* hr) {
3618 // Here we check that the CSet region's RSet is ready for parallel
3619 // iteration. The fields that we'll verify are only manipulated
3620 // when the region is part of a CSet and is collected. Afterwards,
3621 // we reset these fields when we clear the region's RSet (when the
3622 // region is freed) so they are ready when the region is
3623 // re-allocated. The only exception to this is if there's an
3624 // evacuation failure and instead of freeing the region we leave
3625 // it in the heap. In that case, we reset these fields during
3626 // evacuation failure handling.
3627 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3628
3629 // Here's a good place to add any other checks we'd like to
3630 // perform on CSet regions.
3631 return false;
3632 }
3633 };
3634 #endif // ASSERT
3635
3636 uint G1CollectedHeap::num_task_queues() const {
3637 return _task_queues->size();
3638 }
3639
3640 #if TASKQUEUE_STATS
3641 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3642 st->print_raw_cr("GC Task Stats");
3643 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3644 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3645 }
3646
3647 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3648 print_taskqueue_stats_hdr(st);
3649
3650 TaskQueueStats totals;
3651 const uint n = num_task_queues();
3652 for (uint i = 0; i < n; ++i) {
3653 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3654 totals += task_queue(i)->stats;
3655 }
3656 st->print_raw("tot "); totals.print(st); st->cr();
3657
3658 DEBUG_ONLY(totals.verify());
3659 }
3660
3661 void G1CollectedHeap::reset_taskqueue_stats() {
3662 const uint n = num_task_queues();
3663 for (uint i = 0; i < n; ++i) {
3664 task_queue(i)->stats.reset();
3665 }
3666 }
3667 #endif // TASKQUEUE_STATS
3668
3669 void G1CollectedHeap::log_gc_header() {
3670 if (!G1Log::fine()) {
3671 return;
3672 }
3673
3674 gclog_or_tty->gclog_stamp();
3675
3676 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3677 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3678 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3679
3680 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3681 }
3682
3683 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3684 if (!G1Log::fine()) {
3685 return;
3686 }
3687
3688 if (G1Log::finer()) {
3689 if (evacuation_failed()) {
3690 gclog_or_tty->print(" (to-space exhausted)");
3691 }
3692 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3693 g1_policy()->print_phases(pause_time_sec);
3694 g1_policy()->print_detailed_heap_transition();
3695 } else {
3696 if (evacuation_failed()) {
3697 gclog_or_tty->print("--");
3698 }
3699 g1_policy()->print_heap_transition();
3700 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3701 }
3702 gclog_or_tty->flush();
3703 }
3704
3705 void G1CollectedHeap::wait_for_root_region_scanning() {
3706 double scan_wait_start = os::elapsedTime();
3707 // We have to wait until the CM threads finish scanning the
3708 // root regions as it's the only way to ensure that all the
3709 // objects on them have been correctly scanned before we start
3710 // moving them during the GC.
3711 bool waited = _cm->root_regions()->wait_until_scan_finished();
3712 double wait_time_ms = 0.0;
3713 if (waited) {
3714 double scan_wait_end = os::elapsedTime();
3715 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3716 }
3717 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3718 }
3719
3720 bool
3721 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3722 assert_at_safepoint(true /* should_be_vm_thread */);
3723 guarantee(!is_gc_active(), "collection is not reentrant");
3724
3725 if (GC_locker::check_active_before_gc()) {
3726 return false;
3727 }
3728
3729 _gc_timer_stw->register_gc_start();
3730
3731 GCIdMark gc_id_mark;
3732 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3733
3734 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3735 ResourceMark rm;
3736
3737 wait_for_root_region_scanning();
3738
3739 G1Log::update_level();
3740 print_heap_before_gc();
3741 trace_heap_before_gc(_gc_tracer_stw);
3742
3743 verify_region_sets_optional();
3744 verify_dirty_young_regions();
3745
3746 // This call will decide whether this pause is an initial-mark
3747 // pause. If it is, during_initial_mark_pause() will return true
3748 // for the duration of this pause.
3749 g1_policy()->decide_on_conc_mark_initiation();
3750
3751 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3752 assert(!collector_state()->during_initial_mark_pause() ||
3753 collector_state()->gcs_are_young(), "sanity");
3754
3755 // We also do not allow mixed GCs during marking.
3756 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3757
3758 // Record whether this pause is an initial mark. When the current
3759 // thread has completed its logging output and it's safe to signal
3760 // the CM thread, the flag's value in the policy has been reset.
3761 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3762
3763 // Inner scope for scope based logging, timers, and stats collection
3764 {
3765 EvacuationInfo evacuation_info;
3766
3767 if (collector_state()->during_initial_mark_pause()) {
3768 // We are about to start a marking cycle, so we increment the
3769 // full collection counter.
3770 increment_old_marking_cycles_started();
3771 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3772 }
3773
3774 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3775
3776 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3777
3778 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3779 workers()->active_workers(),
3780 Threads::number_of_non_daemon_threads());
3781 workers()->set_active_workers(active_workers);
3782
3783 double pause_start_sec = os::elapsedTime();
3784 g1_policy()->note_gc_start(active_workers);
3785 log_gc_header();
3786
3787 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3788 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3789
3790 // If the secondary_free_list is not empty, append it to the
3791 // free_list. No need to wait for the cleanup operation to finish;
3792 // the region allocation code will check the secondary_free_list
3793 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3794 // set, skip this step so that the region allocation code has to
3795 // get entries from the secondary_free_list.
3796 if (!G1StressConcRegionFreeing) {
3797 append_secondary_free_list_if_not_empty_with_lock();
3798 }
3799
3800 assert(check_young_list_well_formed(), "young list should be well formed");
3801
3802 // Don't dynamically change the number of GC threads this early. A value of
3803 // 0 is used to indicate serial work. When parallel work is done,
3804 // it will be set.
3805
3806 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3807 IsGCActiveMark x;
3808
3809 gc_prologue(false);
3810 increment_total_collections(false /* full gc */);
3811 increment_gc_time_stamp();
3812
3813 verify_before_gc();
3814
3815 check_bitmaps("GC Start");
3816
3817 #if defined(COMPILER2) || INCLUDE_JVMCI
3818 DerivedPointerTable::clear();
3819 #endif
3820
3821 // Please see comment in g1CollectedHeap.hpp and
3822 // G1CollectedHeap::ref_processing_init() to see how
3823 // reference processing currently works in G1.
3824
3825 // Enable discovery in the STW reference processor
3826 ref_processor_stw()->enable_discovery();
3827
3828 {
3829 // We want to temporarily turn off discovery by the
3830 // CM ref processor, if necessary, and turn it back on
3831 // on again later if we do. Using a scoped
3832 // NoRefDiscovery object will do this.
3833 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3834
3835 // Forget the current alloc region (we might even choose it to be part
3836 // of the collection set!).
3837 _allocator->release_mutator_alloc_region();
3838
3839 // We should call this after we retire the mutator alloc
3840 // region(s) so that all the ALLOC / RETIRE events are generated
3841 // before the start GC event.
3842 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3843
3844 // This timing is only used by the ergonomics to handle our pause target.
3845 // It is unclear why this should not include the full pause. We will
3846 // investigate this in CR 7178365.
3847 //
3848 // Preserving the old comment here if that helps the investigation:
3849 //
3850 // The elapsed time induced by the start time below deliberately elides
3851 // the possible verification above.
3852 double sample_start_time_sec = os::elapsedTime();
3853
3854 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3855
3856 if (collector_state()->during_initial_mark_pause()) {
3857 concurrent_mark()->checkpointRootsInitialPre();
3858 }
3859
3860 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3861 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3862
3863 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3864
3865 // Make sure the remembered sets are up to date. This needs to be
3866 // done before register_humongous_regions_with_cset(), because the
3867 // remembered sets are used there to choose eager reclaim candidates.
3868 // If the remembered sets are not up to date we might miss some
3869 // entries that need to be handled.
3870 g1_rem_set()->cleanupHRRS();
3871
3872 register_humongous_regions_with_cset();
3873
3874 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3875
3876 _cm->note_start_of_gc();
3877 // We call this after finalize_cset() to
3878 // ensure that the CSet has been finalized.
3879 _cm->verify_no_cset_oops();
3880
3881 if (_hr_printer.is_active()) {
3882 HeapRegion* hr = g1_policy()->collection_set();
3883 while (hr != NULL) {
3884 _hr_printer.cset(hr);
3885 hr = hr->next_in_collection_set();
3886 }
3887 }
3888
3889 #ifdef ASSERT
3890 VerifyCSetClosure cl;
3891 collection_set_iterate(&cl);
3892 #endif // ASSERT
3893
3894 // Initialize the GC alloc regions.
3895 _allocator->init_gc_alloc_regions(evacuation_info);
3896
3897 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3898 pre_evacuate_collection_set();
3899
3900 // Actually do the work...
3901 evacuate_collection_set(evacuation_info, &per_thread_states);
3902
3903 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3904
3905 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3906 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3907
3908 eagerly_reclaim_humongous_regions();
3909
3910 g1_policy()->clear_collection_set();
3911
3912 // Start a new incremental collection set for the next pause.
3913 g1_policy()->start_incremental_cset_building();
3914
3915 clear_cset_fast_test();
3916
3917 _young_list->reset_sampled_info();
3918
3919 // Don't check the whole heap at this point as the
3920 // GC alloc regions from this pause have been tagged
3921 // as survivors and moved on to the survivor list.
3922 // Survivor regions will fail the !is_young() check.
3923 assert(check_young_list_empty(false /* check_heap */),
3924 "young list should be empty");
3925
3926 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3927 _young_list->first_survivor_region(),
3928 _young_list->last_survivor_region());
3929
3930 _young_list->reset_auxilary_lists();
3931
3932 if (evacuation_failed()) {
3933 set_used(recalculate_used());
3934 if (_archive_allocator != NULL) {
3935 _archive_allocator->clear_used();
3936 }
3937 for (uint i = 0; i < ParallelGCThreads; i++) {
3938 if (_evacuation_failed_info_array[i].has_failed()) {
3939 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3940 }
3941 }
3942 } else {
3943 // The "used" of the the collection set have already been subtracted
3944 // when they were freed. Add in the bytes evacuated.
3945 increase_used(g1_policy()->bytes_copied_during_gc());
3946 }
3947
3948 if (collector_state()->during_initial_mark_pause()) {
3949 // We have to do this before we notify the CM threads that
3950 // they can start working to make sure that all the
3951 // appropriate initialization is done on the CM object.
3952 concurrent_mark()->checkpointRootsInitialPost();
3953 collector_state()->set_mark_in_progress(true);
3954 // Note that we don't actually trigger the CM thread at
3955 // this point. We do that later when we're sure that
3956 // the current thread has completed its logging output.
3957 }
3958
3959 allocate_dummy_regions();
3960
3961 _allocator->init_mutator_alloc_region();
3962
3963 {
3964 size_t expand_bytes = g1_policy()->expansion_amount();
3965 if (expand_bytes > 0) {
3966 size_t bytes_before = capacity();
3967 // No need for an ergo verbose message here,
3968 // expansion_amount() does this when it returns a value > 0.
3969 double expand_ms;
3970 if (!expand(expand_bytes, &expand_ms)) {
3971 // We failed to expand the heap. Cannot do anything about it.
3972 }
3973 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3974 }
3975 }
3976
3977 // We redo the verification but now wrt to the new CSet which
3978 // has just got initialized after the previous CSet was freed.
3979 _cm->verify_no_cset_oops();
3980 _cm->note_end_of_gc();
3981
3982 // This timing is only used by the ergonomics to handle our pause target.
3983 // It is unclear why this should not include the full pause. We will
3984 // investigate this in CR 7178365.
3985 double sample_end_time_sec = os::elapsedTime();
3986 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3987 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3988 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3989
3990 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3991 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3992
3993 MemoryService::track_memory_usage();
3994
3995 // In prepare_for_verify() below we'll need to scan the deferred
3996 // update buffers to bring the RSets up-to-date if
3997 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3998 // the update buffers we'll probably need to scan cards on the
3999 // regions we just allocated to (i.e., the GC alloc
4000 // regions). However, during the last GC we called
4001 // set_saved_mark() on all the GC alloc regions, so card
4002 // scanning might skip the [saved_mark_word()...top()] area of
4003 // those regions (i.e., the area we allocated objects into
4004 // during the last GC). But it shouldn't. Given that
4005 // saved_mark_word() is conditional on whether the GC time stamp
4006 // on the region is current or not, by incrementing the GC time
4007 // stamp here we invalidate all the GC time stamps on all the
4008 // regions and saved_mark_word() will simply return top() for
4009 // all the regions. This is a nicer way of ensuring this rather
4010 // than iterating over the regions and fixing them. In fact, the
4011 // GC time stamp increment here also ensures that
4012 // saved_mark_word() will return top() between pauses, i.e.,
4013 // during concurrent refinement. So we don't need the
4014 // is_gc_active() check to decided which top to use when
4015 // scanning cards (see CR 7039627).
4016 increment_gc_time_stamp();
4017
4018 verify_after_gc();
4019 check_bitmaps("GC End");
4020
4021 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4022 ref_processor_stw()->verify_no_references_recorded();
4023
4024 // CM reference discovery will be re-enabled if necessary.
4025 }
4026
4027 // We should do this after we potentially expand the heap so
4028 // that all the COMMIT events are generated before the end GC
4029 // event, and after we retire the GC alloc regions so that all
4030 // RETIRE events are generated before the end GC event.
4031 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4032
4033 #ifdef TRACESPINNING
4034 ParallelTaskTerminator::print_termination_counts();
4035 #endif
4036
4037 gc_epilogue(false);
4038 }
4039
4040 // Print the remainder of the GC log output.
4041 log_gc_footer(os::elapsedTime() - pause_start_sec);
4042
4043 // It is not yet to safe to tell the concurrent mark to
4044 // start as we have some optional output below. We don't want the
4045 // output from the concurrent mark thread interfering with this
4046 // logging output either.
4047
4048 _hrm.verify_optional();
4049 verify_region_sets_optional();
4050
4051 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4052 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4053
4054 print_heap_after_gc();
4055 trace_heap_after_gc(_gc_tracer_stw);
4056
4057 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4058 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4059 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4060 // before any GC notifications are raised.
4061 g1mm()->update_sizes();
4062
4063 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4064 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4065 _gc_timer_stw->register_gc_end();
4066 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4067 }
4068 // It should now be safe to tell the concurrent mark thread to start
4069 // without its logging output interfering with the logging output
4070 // that came from the pause.
4071
4072 if (should_start_conc_mark) {
4073 // CAUTION: after the doConcurrentMark() call below,
4074 // the concurrent marking thread(s) could be running
4075 // concurrently with us. Make sure that anything after
4076 // this point does not assume that we are the only GC thread
4077 // running. Note: of course, the actual marking work will
4078 // not start until the safepoint itself is released in
4079 // SuspendibleThreadSet::desynchronize().
4080 doConcurrentMark();
4081 }
4082
4083 return true;
4084 }
4085
4086 void G1CollectedHeap::remove_self_forwarding_pointers() {
4087 double remove_self_forwards_start = os::elapsedTime();
4088
4089 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4090 workers()->run_task(&rsfp_task);
4091
4092 // Now restore saved marks, if any.
4093 for (uint i = 0; i < ParallelGCThreads; i++) {
4094 OopAndMarkOopStack& cur = _preserved_objs[i];
4095 while (!cur.is_empty()) {
4096 OopAndMarkOop elem = cur.pop();
4097 elem.set_mark();
4098 }
4099 cur.clear(true);
4100 }
4101
4102 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4103 }
4104
4105 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4106 if (!_evacuation_failed) {
4107 _evacuation_failed = true;
4108 }
4109
4110 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4111
4112 // We want to call the "for_promotion_failure" version only in the
4113 // case of a promotion failure.
4114 if (m->must_be_preserved_for_promotion_failure(obj)) {
4115 OopAndMarkOop elem(obj, m);
4116 _preserved_objs[worker_id].push(elem);
4117 }
4118 }
4119
4120 class G1ParEvacuateFollowersClosure : public VoidClosure {
4121 private:
4122 double _start_term;
4123 double _term_time;
4124 size_t _term_attempts;
4125
4126 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4127 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4128 protected:
4129 G1CollectedHeap* _g1h;
4130 G1ParScanThreadState* _par_scan_state;
4131 RefToScanQueueSet* _queues;
4132 ParallelTaskTerminator* _terminator;
4133
4134 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4135 RefToScanQueueSet* queues() { return _queues; }
4136 ParallelTaskTerminator* terminator() { return _terminator; }
4137
4138 public:
4139 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4140 G1ParScanThreadState* par_scan_state,
4141 RefToScanQueueSet* queues,
4142 ParallelTaskTerminator* terminator)
4143 : _g1h(g1h), _par_scan_state(par_scan_state),
4144 _queues(queues), _terminator(terminator),
4145 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4146
4147 void do_void();
4148
4149 double term_time() const { return _term_time; }
4150 size_t term_attempts() const { return _term_attempts; }
4151
4152 private:
4153 inline bool offer_termination();
4154 };
4155
4156 bool G1ParEvacuateFollowersClosure::offer_termination() {
4157 G1ParScanThreadState* const pss = par_scan_state();
4158 start_term_time();
4159 const bool res = terminator()->offer_termination();
4160 end_term_time();
4161 return res;
4162 }
4163
4164 void G1ParEvacuateFollowersClosure::do_void() {
4165 G1ParScanThreadState* const pss = par_scan_state();
4166 pss->trim_queue();
4167 do {
4168 pss->steal_and_trim_queue(queues());
4169 } while (!offer_termination());
4170 }
4171
4172 class G1ParTask : public AbstractGangTask {
4173 protected:
4174 G1CollectedHeap* _g1h;
4175 G1ParScanThreadStateSet* _pss;
4176 RefToScanQueueSet* _queues;
4177 G1RootProcessor* _root_processor;
4178 ParallelTaskTerminator _terminator;
4179 uint _n_workers;
4180
4181 public:
4182 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4183 : AbstractGangTask("G1 collection"),
4184 _g1h(g1h),
4185 _pss(per_thread_states),
4186 _queues(task_queues),
4187 _root_processor(root_processor),
4188 _terminator(n_workers, _queues),
4189 _n_workers(n_workers)
4190 {}
4191
4192 void work(uint worker_id) {
4193 if (worker_id >= _n_workers) return; // no work needed this round
4194
4195 double start_sec = os::elapsedTime();
4196 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4197
4198 {
4199 ResourceMark rm;
4200 HandleMark hm;
4201
4202 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4203
4204 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4205 pss->set_ref_processor(rp);
4206
4207 double start_strong_roots_sec = os::elapsedTime();
4208
4209 _root_processor->evacuate_roots(pss->closures(), worker_id);
4210
4211 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4212
4213 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4214 // treating the nmethods visited to act as roots for concurrent marking.
4215 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4216 // objects copied by the current evacuation.
4217 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4218 pss->closures()->weak_codeblobs(),
4219 worker_id);
4220
4221 _pss->add_cards_scanned(worker_id, cards_scanned);
4222
4223 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4224
4225 double term_sec = 0.0;
4226 size_t evac_term_attempts = 0;
4227 {
4228 double start = os::elapsedTime();
4229 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4230 evac.do_void();
4231
4232 evac_term_attempts = evac.term_attempts();
4233 term_sec = evac.term_time();
4234 double elapsed_sec = os::elapsedTime() - start;
4235 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4236 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4237 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4238 }
4239
4240 assert(pss->queue_is_empty(), "should be empty");
4241
4242 if (PrintTerminationStats) {
4243 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4244 size_t lab_waste;
4245 size_t lab_undo_waste;
4246 pss->waste(lab_waste, lab_undo_waste);
4247 _g1h->print_termination_stats(gclog_or_tty,
4248 worker_id,
4249 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4250 strong_roots_sec * 1000.0, /* strong roots time */
4251 term_sec * 1000.0, /* evac term time */
4252 evac_term_attempts, /* evac term attempts */
4253 lab_waste, /* alloc buffer waste */
4254 lab_undo_waste /* undo waste */
4255 );
4256 }
4257
4258 // Close the inner scope so that the ResourceMark and HandleMark
4259 // destructors are executed here and are included as part of the
4260 // "GC Worker Time".
4261 }
4262 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4263 }
4264 };
4265
4266 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4267 st->print_raw_cr("GC Termination Stats");
4268 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4269 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4270 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4271 }
4272
4273 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4274 uint worker_id,
4275 double elapsed_ms,
4276 double strong_roots_ms,
4277 double term_ms,
4278 size_t term_attempts,
4279 size_t alloc_buffer_waste,
4280 size_t undo_waste) const {
4281 st->print_cr("%3d %9.2f %9.2f %6.2f "
4282 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4283 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4284 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4285 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4286 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4287 alloc_buffer_waste * HeapWordSize / K,
4288 undo_waste * HeapWordSize / K);
4289 }
4290
4291 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4292 private:
4293 BoolObjectClosure* _is_alive;
4294 int _initial_string_table_size;
4295 int _initial_symbol_table_size;
4296
4297 bool _process_strings;
4298 int _strings_processed;
4299 int _strings_removed;
4300
4301 bool _process_symbols;
4302 int _symbols_processed;
4303 int _symbols_removed;
4304
4305 public:
4306 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4307 AbstractGangTask("String/Symbol Unlinking"),
4308 _is_alive(is_alive),
4309 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4310 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4311
4312 _initial_string_table_size = StringTable::the_table()->table_size();
4313 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4314 if (process_strings) {
4315 StringTable::clear_parallel_claimed_index();
4316 }
4317 if (process_symbols) {
4318 SymbolTable::clear_parallel_claimed_index();
4319 }
4320 }
4321
4322 ~G1StringSymbolTableUnlinkTask() {
4323 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4324 "claim value %d after unlink less than initial string table size %d",
4325 StringTable::parallel_claimed_index(), _initial_string_table_size);
4326 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4327 "claim value %d after unlink less than initial symbol table size %d",
4328 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4329
4330 if (G1TraceStringSymbolTableScrubbing) {
4331 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4332 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4333 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4334 strings_processed(), strings_removed(),
4335 symbols_processed(), symbols_removed());
4336 }
4337 }
4338
4339 void work(uint worker_id) {
4340 int strings_processed = 0;
4341 int strings_removed = 0;
4342 int symbols_processed = 0;
4343 int symbols_removed = 0;
4344 if (_process_strings) {
4345 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4346 Atomic::add(strings_processed, &_strings_processed);
4347 Atomic::add(strings_removed, &_strings_removed);
4348 }
4349 if (_process_symbols) {
4350 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4351 Atomic::add(symbols_processed, &_symbols_processed);
4352 Atomic::add(symbols_removed, &_symbols_removed);
4353 }
4354 }
4355
4356 size_t strings_processed() const { return (size_t)_strings_processed; }
4357 size_t strings_removed() const { return (size_t)_strings_removed; }
4358
4359 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4360 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4361 };
4362
4363 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4364 private:
4365 static Monitor* _lock;
4366
4367 BoolObjectClosure* const _is_alive;
4368 const bool _unloading_occurred;
4369 const uint _num_workers;
4370
4371 // Variables used to claim nmethods.
4372 nmethod* _first_nmethod;
4373 volatile nmethod* _claimed_nmethod;
4374
4375 // The list of nmethods that need to be processed by the second pass.
4376 volatile nmethod* _postponed_list;
4377 volatile uint _num_entered_barrier;
4378
4379 public:
4380 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4381 _is_alive(is_alive),
4382 _unloading_occurred(unloading_occurred),
4383 _num_workers(num_workers),
4384 _first_nmethod(NULL),
4385 _claimed_nmethod(NULL),
4386 _postponed_list(NULL),
4387 _num_entered_barrier(0)
4388 {
4389 nmethod::increase_unloading_clock();
4390 // Get first alive nmethod
4391 NMethodIterator iter = NMethodIterator();
4392 if(iter.next_alive()) {
4393 _first_nmethod = iter.method();
4394 }
4395 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4396 }
4397
4398 ~G1CodeCacheUnloadingTask() {
4399 CodeCache::verify_clean_inline_caches();
4400
4401 CodeCache::set_needs_cache_clean(false);
4402 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4403
4404 CodeCache::verify_icholder_relocations();
4405 }
4406
4407 private:
4408 void add_to_postponed_list(nmethod* nm) {
4409 nmethod* old;
4410 do {
4411 old = (nmethod*)_postponed_list;
4412 nm->set_unloading_next(old);
4413 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4414 }
4415
4416 void clean_nmethod(nmethod* nm) {
4417 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4418
4419 if (postponed) {
4420 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4421 add_to_postponed_list(nm);
4422 }
4423
4424 // Mark that this thread has been cleaned/unloaded.
4425 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4426 nm->set_unloading_clock(nmethod::global_unloading_clock());
4427 }
4428
4429 void clean_nmethod_postponed(nmethod* nm) {
4430 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4431 }
4432
4433 static const int MaxClaimNmethods = 16;
4434
4435 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4436 nmethod* first;
4437 NMethodIterator last;
4438
4439 do {
4440 *num_claimed_nmethods = 0;
4441
4442 first = (nmethod*)_claimed_nmethod;
4443 last = NMethodIterator(first);
4444
4445 if (first != NULL) {
4446
4447 for (int i = 0; i < MaxClaimNmethods; i++) {
4448 if (!last.next_alive()) {
4449 break;
4450 }
4451 claimed_nmethods[i] = last.method();
4452 (*num_claimed_nmethods)++;
4453 }
4454 }
4455
4456 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4457 }
4458
4459 nmethod* claim_postponed_nmethod() {
4460 nmethod* claim;
4461 nmethod* next;
4462
4463 do {
4464 claim = (nmethod*)_postponed_list;
4465 if (claim == NULL) {
4466 return NULL;
4467 }
4468
4469 next = claim->unloading_next();
4470
4471 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4472
4473 return claim;
4474 }
4475
4476 public:
4477 // Mark that we're done with the first pass of nmethod cleaning.
4478 void barrier_mark(uint worker_id) {
4479 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4480 _num_entered_barrier++;
4481 if (_num_entered_barrier == _num_workers) {
4482 ml.notify_all();
4483 }
4484 }
4485
4486 // See if we have to wait for the other workers to
4487 // finish their first-pass nmethod cleaning work.
4488 void barrier_wait(uint worker_id) {
4489 if (_num_entered_barrier < _num_workers) {
4490 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4491 while (_num_entered_barrier < _num_workers) {
4492 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4493 }
4494 }
4495 }
4496
4497 // Cleaning and unloading of nmethods. Some work has to be postponed
4498 // to the second pass, when we know which nmethods survive.
4499 void work_first_pass(uint worker_id) {
4500 // The first nmethods is claimed by the first worker.
4501 if (worker_id == 0 && _first_nmethod != NULL) {
4502 clean_nmethod(_first_nmethod);
4503 _first_nmethod = NULL;
4504 }
4505
4506 int num_claimed_nmethods;
4507 nmethod* claimed_nmethods[MaxClaimNmethods];
4508
4509 while (true) {
4510 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4511
4512 if (num_claimed_nmethods == 0) {
4513 break;
4514 }
4515
4516 for (int i = 0; i < num_claimed_nmethods; i++) {
4517 clean_nmethod(claimed_nmethods[i]);
4518 }
4519 }
4520 }
4521
4522 void work_second_pass(uint worker_id) {
4523 nmethod* nm;
4524 // Take care of postponed nmethods.
4525 while ((nm = claim_postponed_nmethod()) != NULL) {
4526 clean_nmethod_postponed(nm);
4527 }
4528 }
4529 };
4530
4531 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4532
4533 class G1KlassCleaningTask : public StackObj {
4534 BoolObjectClosure* _is_alive;
4535 volatile jint _clean_klass_tree_claimed;
4536 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4537
4538 public:
4539 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4540 _is_alive(is_alive),
4541 _clean_klass_tree_claimed(0),
4542 _klass_iterator() {
4543 }
4544
4545 private:
4546 bool claim_clean_klass_tree_task() {
4547 if (_clean_klass_tree_claimed) {
4548 return false;
4549 }
4550
4551 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4552 }
4553
4554 InstanceKlass* claim_next_klass() {
4555 Klass* klass;
4556 do {
4557 klass =_klass_iterator.next_klass();
4558 } while (klass != NULL && !klass->is_instance_klass());
4559
4560 // this can be null so don't call InstanceKlass::cast
4561 return static_cast<InstanceKlass*>(klass);
4562 }
4563
4564 public:
4565
4566 void clean_klass(InstanceKlass* ik) {
4567 ik->clean_weak_instanceklass_links(_is_alive);
4568 }
4569
4570 void work() {
4571 ResourceMark rm;
4572
4573 // One worker will clean the subklass/sibling klass tree.
4574 if (claim_clean_klass_tree_task()) {
4575 Klass::clean_subklass_tree(_is_alive);
4576 }
4577
4578 // All workers will help cleaning the classes,
4579 InstanceKlass* klass;
4580 while ((klass = claim_next_klass()) != NULL) {
4581 clean_klass(klass);
4582 }
4583 }
4584 };
4585
4586 // To minimize the remark pause times, the tasks below are done in parallel.
4587 class G1ParallelCleaningTask : public AbstractGangTask {
4588 private:
4589 G1StringSymbolTableUnlinkTask _string_symbol_task;
4590 G1CodeCacheUnloadingTask _code_cache_task;
4591 G1KlassCleaningTask _klass_cleaning_task;
4592
4593 public:
4594 // The constructor is run in the VMThread.
4595 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4596 AbstractGangTask("Parallel Cleaning"),
4597 _string_symbol_task(is_alive, process_strings, process_symbols),
4598 _code_cache_task(num_workers, is_alive, unloading_occurred),
4599 _klass_cleaning_task(is_alive) {
4600 }
4601
4602 // The parallel work done by all worker threads.
4603 void work(uint worker_id) {
4604 // Do first pass of code cache cleaning.
4605 _code_cache_task.work_first_pass(worker_id);
4606
4607 // Let the threads mark that the first pass is done.
4608 _code_cache_task.barrier_mark(worker_id);
4609
4610 // Clean the Strings and Symbols.
4611 _string_symbol_task.work(worker_id);
4612
4613 // Wait for all workers to finish the first code cache cleaning pass.
4614 _code_cache_task.barrier_wait(worker_id);
4615
4616 // Do the second code cache cleaning work, which realize on
4617 // the liveness information gathered during the first pass.
4618 _code_cache_task.work_second_pass(worker_id);
4619
4620 // Clean all klasses that were not unloaded.
4621 _klass_cleaning_task.work();
4622 }
4623 };
4624
4625
4626 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4627 bool process_strings,
4628 bool process_symbols,
4629 bool class_unloading_occurred) {
4630 uint n_workers = workers()->active_workers();
4631
4632 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4633 n_workers, class_unloading_occurred);
4634 workers()->run_task(&g1_unlink_task);
4635 }
4636
4637 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4638 bool process_strings, bool process_symbols) {
4639 {
4640 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4641 workers()->run_task(&g1_unlink_task);
4642 }
4643
4644 if (G1StringDedup::is_enabled()) {
4645 G1StringDedup::unlink(is_alive);
4646 }
4647 }
4648
4649 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4650 private:
4651 DirtyCardQueueSet* _queue;
4652 public:
4653 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4654
4655 virtual void work(uint worker_id) {
4656 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4657 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4658
4659 RedirtyLoggedCardTableEntryClosure cl;
4660 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4661
4662 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4663 }
4664 };
4665
4666 void G1CollectedHeap::redirty_logged_cards() {
4667 double redirty_logged_cards_start = os::elapsedTime();
4668
4669 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4670 dirty_card_queue_set().reset_for_par_iteration();
4671 workers()->run_task(&redirty_task);
4672
4673 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4674 dcq.merge_bufferlists(&dirty_card_queue_set());
4675 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4676
4677 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4678 }
4679
4680 // Weak Reference Processing support
4681
4682 // An always "is_alive" closure that is used to preserve referents.
4683 // If the object is non-null then it's alive. Used in the preservation
4684 // of referent objects that are pointed to by reference objects
4685 // discovered by the CM ref processor.
4686 class G1AlwaysAliveClosure: public BoolObjectClosure {
4687 G1CollectedHeap* _g1;
4688 public:
4689 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4690 bool do_object_b(oop p) {
4691 if (p != NULL) {
4692 return true;
4693 }
4694 return false;
4695 }
4696 };
4697
4698 bool G1STWIsAliveClosure::do_object_b(oop p) {
4699 // An object is reachable if it is outside the collection set,
4700 // or is inside and copied.
4701 return !_g1->is_in_cset(p) || p->is_forwarded();
4702 }
4703
4704 // Non Copying Keep Alive closure
4705 class G1KeepAliveClosure: public OopClosure {
4706 G1CollectedHeap* _g1;
4707 public:
4708 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4709 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4710 void do_oop(oop* p) {
4711 oop obj = *p;
4712 assert(obj != NULL, "the caller should have filtered out NULL values");
4713
4714 const InCSetState cset_state = _g1->in_cset_state(obj);
4715 if (!cset_state.is_in_cset_or_humongous()) {
4716 return;
4717 }
4718 if (cset_state.is_in_cset()) {
4719 assert( obj->is_forwarded(), "invariant" );
4720 *p = obj->forwardee();
4721 } else {
4722 assert(!obj->is_forwarded(), "invariant" );
4723 assert(cset_state.is_humongous(),
4724 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4725 _g1->set_humongous_is_live(obj);
4726 }
4727 }
4728 };
4729
4730 // Copying Keep Alive closure - can be called from both
4731 // serial and parallel code as long as different worker
4732 // threads utilize different G1ParScanThreadState instances
4733 // and different queues.
4734
4735 class G1CopyingKeepAliveClosure: public OopClosure {
4736 G1CollectedHeap* _g1h;
4737 OopClosure* _copy_non_heap_obj_cl;
4738 G1ParScanThreadState* _par_scan_state;
4739
4740 public:
4741 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4742 OopClosure* non_heap_obj_cl,
4743 G1ParScanThreadState* pss):
4744 _g1h(g1h),
4745 _copy_non_heap_obj_cl(non_heap_obj_cl),
4746 _par_scan_state(pss)
4747 {}
4748
4749 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4750 virtual void do_oop( oop* p) { do_oop_work(p); }
4751
4752 template <class T> void do_oop_work(T* p) {
4753 oop obj = oopDesc::load_decode_heap_oop(p);
4754
4755 if (_g1h->is_in_cset_or_humongous(obj)) {
4756 // If the referent object has been forwarded (either copied
4757 // to a new location or to itself in the event of an
4758 // evacuation failure) then we need to update the reference
4759 // field and, if both reference and referent are in the G1
4760 // heap, update the RSet for the referent.
4761 //
4762 // If the referent has not been forwarded then we have to keep
4763 // it alive by policy. Therefore we have copy the referent.
4764 //
4765 // If the reference field is in the G1 heap then we can push
4766 // on the PSS queue. When the queue is drained (after each
4767 // phase of reference processing) the object and it's followers
4768 // will be copied, the reference field set to point to the
4769 // new location, and the RSet updated. Otherwise we need to
4770 // use the the non-heap or metadata closures directly to copy
4771 // the referent object and update the pointer, while avoiding
4772 // updating the RSet.
4773
4774 if (_g1h->is_in_g1_reserved(p)) {
4775 _par_scan_state->push_on_queue(p);
4776 } else {
4777 assert(!Metaspace::contains((const void*)p),
4778 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4779 _copy_non_heap_obj_cl->do_oop(p);
4780 }
4781 }
4782 }
4783 };
4784
4785 // Serial drain queue closure. Called as the 'complete_gc'
4786 // closure for each discovered list in some of the
4787 // reference processing phases.
4788
4789 class G1STWDrainQueueClosure: public VoidClosure {
4790 protected:
4791 G1CollectedHeap* _g1h;
4792 G1ParScanThreadState* _par_scan_state;
4793
4794 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4795
4796 public:
4797 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4798 _g1h(g1h),
4799 _par_scan_state(pss)
4800 { }
4801
4802 void do_void() {
4803 G1ParScanThreadState* const pss = par_scan_state();
4804 pss->trim_queue();
4805 }
4806 };
4807
4808 // Parallel Reference Processing closures
4809
4810 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4811 // processing during G1 evacuation pauses.
4812
4813 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4814 private:
4815 G1CollectedHeap* _g1h;
4816 G1ParScanThreadStateSet* _pss;
4817 RefToScanQueueSet* _queues;
4818 WorkGang* _workers;
4819 uint _active_workers;
4820
4821 public:
4822 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4823 G1ParScanThreadStateSet* per_thread_states,
4824 WorkGang* workers,
4825 RefToScanQueueSet *task_queues,
4826 uint n_workers) :
4827 _g1h(g1h),
4828 _pss(per_thread_states),
4829 _queues(task_queues),
4830 _workers(workers),
4831 _active_workers(n_workers)
4832 {
4833 assert(n_workers > 0, "shouldn't call this otherwise");
4834 }
4835
4836 // Executes the given task using concurrent marking worker threads.
4837 virtual void execute(ProcessTask& task);
4838 virtual void execute(EnqueueTask& task);
4839 };
4840
4841 // Gang task for possibly parallel reference processing
4842
4843 class G1STWRefProcTaskProxy: public AbstractGangTask {
4844 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4845 ProcessTask& _proc_task;
4846 G1CollectedHeap* _g1h;
4847 G1ParScanThreadStateSet* _pss;
4848 RefToScanQueueSet* _task_queues;
4849 ParallelTaskTerminator* _terminator;
4850
4851 public:
4852 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4853 G1CollectedHeap* g1h,
4854 G1ParScanThreadStateSet* per_thread_states,
4855 RefToScanQueueSet *task_queues,
4856 ParallelTaskTerminator* terminator) :
4857 AbstractGangTask("Process reference objects in parallel"),
4858 _proc_task(proc_task),
4859 _g1h(g1h),
4860 _pss(per_thread_states),
4861 _task_queues(task_queues),
4862 _terminator(terminator)
4863 {}
4864
4865 virtual void work(uint worker_id) {
4866 // The reference processing task executed by a single worker.
4867 ResourceMark rm;
4868 HandleMark hm;
4869
4870 G1STWIsAliveClosure is_alive(_g1h);
4871
4872 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4873 pss->set_ref_processor(NULL);
4874
4875 // Keep alive closure.
4876 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4877
4878 // Complete GC closure
4879 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4880
4881 // Call the reference processing task's work routine.
4882 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4883
4884 // Note we cannot assert that the refs array is empty here as not all
4885 // of the processing tasks (specifically phase2 - pp2_work) execute
4886 // the complete_gc closure (which ordinarily would drain the queue) so
4887 // the queue may not be empty.
4888 }
4889 };
4890
4891 // Driver routine for parallel reference processing.
4892 // Creates an instance of the ref processing gang
4893 // task and has the worker threads execute it.
4894 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4895 assert(_workers != NULL, "Need parallel worker threads.");
4896
4897 ParallelTaskTerminator terminator(_active_workers, _queues);
4898 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4899
4900 _workers->run_task(&proc_task_proxy);
4901 }
4902
4903 // Gang task for parallel reference enqueueing.
4904
4905 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4906 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4907 EnqueueTask& _enq_task;
4908
4909 public:
4910 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4911 AbstractGangTask("Enqueue reference objects in parallel"),
4912 _enq_task(enq_task)
4913 { }
4914
4915 virtual void work(uint worker_id) {
4916 _enq_task.work(worker_id);
4917 }
4918 };
4919
4920 // Driver routine for parallel reference enqueueing.
4921 // Creates an instance of the ref enqueueing gang
4922 // task and has the worker threads execute it.
4923
4924 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4925 assert(_workers != NULL, "Need parallel worker threads.");
4926
4927 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4928
4929 _workers->run_task(&enq_task_proxy);
4930 }
4931
4932 // End of weak reference support closures
4933
4934 // Abstract task used to preserve (i.e. copy) any referent objects
4935 // that are in the collection set and are pointed to by reference
4936 // objects discovered by the CM ref processor.
4937
4938 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4939 protected:
4940 G1CollectedHeap* _g1h;
4941 G1ParScanThreadStateSet* _pss;
4942 RefToScanQueueSet* _queues;
4943 ParallelTaskTerminator _terminator;
4944 uint _n_workers;
4945
4946 public:
4947 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4948 AbstractGangTask("ParPreserveCMReferents"),
4949 _g1h(g1h),
4950 _pss(per_thread_states),
4951 _queues(task_queues),
4952 _terminator(workers, _queues),
4953 _n_workers(workers)
4954 { }
4955
4956 void work(uint worker_id) {
4957 ResourceMark rm;
4958 HandleMark hm;
4959
4960 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4961 pss->set_ref_processor(NULL);
4962 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4963
4964 // Is alive closure
4965 G1AlwaysAliveClosure always_alive(_g1h);
4966
4967 // Copying keep alive closure. Applied to referent objects that need
4968 // to be copied.
4969 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4970
4971 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4972
4973 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4974 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4975
4976 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4977 // So this must be true - but assert just in case someone decides to
4978 // change the worker ids.
4979 assert(worker_id < limit, "sanity");
4980 assert(!rp->discovery_is_atomic(), "check this code");
4981
4982 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4983 for (uint idx = worker_id; idx < limit; idx += stride) {
4984 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4985
4986 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4987 while (iter.has_next()) {
4988 // Since discovery is not atomic for the CM ref processor, we
4989 // can see some null referent objects.
4990 iter.load_ptrs(DEBUG_ONLY(true));
4991 oop ref = iter.obj();
4992
4993 // This will filter nulls.
4994 if (iter.is_referent_alive()) {
4995 iter.make_referent_alive();
4996 }
4997 iter.move_to_next();
4998 }
4999 }
5000
5001 // Drain the queue - which may cause stealing
5002 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5003 drain_queue.do_void();
5004 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5005 assert(pss->queue_is_empty(), "should be");
5006 }
5007 };
5008
5009 // Weak Reference processing during an evacuation pause (part 1).
5010 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5011 double ref_proc_start = os::elapsedTime();
5012
5013 ReferenceProcessor* rp = _ref_processor_stw;
5014 assert(rp->discovery_enabled(), "should have been enabled");
5015
5016 // Any reference objects, in the collection set, that were 'discovered'
5017 // by the CM ref processor should have already been copied (either by
5018 // applying the external root copy closure to the discovered lists, or
5019 // by following an RSet entry).
5020 //
5021 // But some of the referents, that are in the collection set, that these
5022 // reference objects point to may not have been copied: the STW ref
5023 // processor would have seen that the reference object had already
5024 // been 'discovered' and would have skipped discovering the reference,
5025 // but would not have treated the reference object as a regular oop.
5026 // As a result the copy closure would not have been applied to the
5027 // referent object.
5028 //
5029 // We need to explicitly copy these referent objects - the references
5030 // will be processed at the end of remarking.
5031 //
5032 // We also need to do this copying before we process the reference
5033 // objects discovered by the STW ref processor in case one of these
5034 // referents points to another object which is also referenced by an
5035 // object discovered by the STW ref processor.
5036
5037 uint no_of_gc_workers = workers()->active_workers();
5038
5039 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5040 per_thread_states,
5041 no_of_gc_workers,
5042 _task_queues);
5043
5044 workers()->run_task(&keep_cm_referents);
5045
5046 // Closure to test whether a referent is alive.
5047 G1STWIsAliveClosure is_alive(this);
5048
5049 // Even when parallel reference processing is enabled, the processing
5050 // of JNI refs is serial and performed serially by the current thread
5051 // rather than by a worker. The following PSS will be used for processing
5052 // JNI refs.
5053
5054 // Use only a single queue for this PSS.
5055 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5056 pss->set_ref_processor(NULL);
5057 assert(pss->queue_is_empty(), "pre-condition");
5058
5059 // Keep alive closure.
5060 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5061
5062 // Serial Complete GC closure
5063 G1STWDrainQueueClosure drain_queue(this, pss);
5064
5065 // Setup the soft refs policy...
5066 rp->setup_policy(false);
5067
5068 ReferenceProcessorStats stats;
5069 if (!rp->processing_is_mt()) {
5070 // Serial reference processing...
5071 stats = rp->process_discovered_references(&is_alive,
5072 &keep_alive,
5073 &drain_queue,
5074 NULL,
5075 _gc_timer_stw);
5076 } else {
5077 // Parallel reference processing
5078 assert(rp->num_q() == no_of_gc_workers, "sanity");
5079 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5080
5081 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5082 stats = rp->process_discovered_references(&is_alive,
5083 &keep_alive,
5084 &drain_queue,
5085 &par_task_executor,
5086 _gc_timer_stw);
5087 }
5088
5089 _gc_tracer_stw->report_gc_reference_stats(stats);
5090
5091 // We have completed copying any necessary live referent objects.
5092 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5093
5094 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5095 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5096 }
5097
5098 // Weak Reference processing during an evacuation pause (part 2).
5099 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5100 double ref_enq_start = os::elapsedTime();
5101
5102 ReferenceProcessor* rp = _ref_processor_stw;
5103 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5104
5105 // Now enqueue any remaining on the discovered lists on to
5106 // the pending list.
5107 if (!rp->processing_is_mt()) {
5108 // Serial reference processing...
5109 rp->enqueue_discovered_references();
5110 } else {
5111 // Parallel reference enqueueing
5112
5113 uint n_workers = workers()->active_workers();
5114
5115 assert(rp->num_q() == n_workers, "sanity");
5116 assert(n_workers <= rp->max_num_q(), "sanity");
5117
5118 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5119 rp->enqueue_discovered_references(&par_task_executor);
5120 }
5121
5122 rp->verify_no_references_recorded();
5123 assert(!rp->discovery_enabled(), "should have been disabled");
5124
5125 // FIXME
5126 // CM's reference processing also cleans up the string and symbol tables.
5127 // Should we do that here also? We could, but it is a serial operation
5128 // and could significantly increase the pause time.
5129
5130 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5131 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5132 }
5133
5134 void G1CollectedHeap::pre_evacuate_collection_set() {
5135 _expand_heap_after_alloc_failure = true;
5136 _evacuation_failed = false;
5137
5138 // Disable the hot card cache.
5139 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5140 hot_card_cache->reset_hot_cache_claimed_index();
5141 hot_card_cache->set_use_cache(false);
5142
5143 }
5144
5145 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5146 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5147
5148 // Should G1EvacuationFailureALot be in effect for this GC?
5149 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5150
5151 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5152 double start_par_time_sec = os::elapsedTime();
5153 double end_par_time_sec;
5154
5155 {
5156 const uint n_workers = workers()->active_workers();
5157 G1RootProcessor root_processor(this, n_workers);
5158 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5159 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5160 if (collector_state()->during_initial_mark_pause()) {
5161 ClassLoaderDataGraph::clear_claimed_marks();
5162 }
5163
5164 // The individual threads will set their evac-failure closures.
5165 if (PrintTerminationStats) {
5166 print_termination_stats_hdr(gclog_or_tty);
5167 }
5168
5169 workers()->run_task(&g1_par_task);
5170 end_par_time_sec = os::elapsedTime();
5171
5172 // Closing the inner scope will execute the destructor
5173 // for the G1RootProcessor object. We record the current
5174 // elapsed time before closing the scope so that time
5175 // taken for the destructor is NOT included in the
5176 // reported parallel time.
5177 }
5178
5179 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5180
5181 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5182 phase_times->record_par_time(par_time_ms);
5183
5184 double code_root_fixup_time_ms =
5185 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5186 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5187
5188 // Process any discovered reference objects - we have
5189 // to do this _before_ we retire the GC alloc regions
5190 // as we may have to copy some 'reachable' referent
5191 // objects (and their reachable sub-graphs) that were
5192 // not copied during the pause.
5193 process_discovered_references(per_thread_states);
5194
5195 if (G1StringDedup::is_enabled()) {
5196 double fixup_start = os::elapsedTime();
5197
5198 G1STWIsAliveClosure is_alive(this);
5199 G1KeepAliveClosure keep_alive(this);
5200 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5201
5202 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5203 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5204 }
5205
5206 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5207
5208 if (evacuation_failed()) {
5209 remove_self_forwarding_pointers();
5210
5211 // Reset the G1EvacuationFailureALot counters and flags
5212 // Note: the values are reset only when an actual
5213 // evacuation failure occurs.
5214 NOT_PRODUCT(reset_evacuation_should_fail();)
5215 }
5216
5217 // Enqueue any remaining references remaining on the STW
5218 // reference processor's discovered lists. We need to do
5219 // this after the card table is cleaned (and verified) as
5220 // the act of enqueueing entries on to the pending list
5221 // will log these updates (and dirty their associated
5222 // cards). We need these updates logged to update any
5223 // RSets.
5224 enqueue_discovered_references(per_thread_states);
5225 }
5226
5227 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5228 _allocator->release_gc_alloc_regions(evacuation_info);
5229
5230 per_thread_states->flush();
5231
5232 record_obj_copy_mem_stats();
5233
5234 _survivor_evac_stats.adjust_desired_plab_sz();
5235 _old_evac_stats.adjust_desired_plab_sz();
5236
5237 // Reset and re-enable the hot card cache.
5238 // Note the counts for the cards in the regions in the
5239 // collection set are reset when the collection set is freed.
5240 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5241 hot_card_cache->reset_hot_cache();
5242 hot_card_cache->set_use_cache(true);
5243
5244 purge_code_root_memory();
5245
5246 redirty_logged_cards();
5247 #if defined(COMPILER2) || INCLUDE_JVMCI
5248 DerivedPointerTable::update_pointers();
5249 #endif
5250 }
5251
5252 void G1CollectedHeap::record_obj_copy_mem_stats() {
5253 g1_policy()->add_last_old_allocated_bytes(_old_evac_stats.allocated() * HeapWordSize);
5254
5255 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5256 create_g1_evac_summary(&_old_evac_stats));
5257 }
5258
5259 void G1CollectedHeap::free_region(HeapRegion* hr,
5260 FreeRegionList* free_list,
5261 bool par,
5262 bool locked) {
5263 assert(!hr->is_free(), "the region should not be free");
5264 assert(!hr->is_empty(), "the region should not be empty");
5265 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5266 assert(free_list != NULL, "pre-condition");
5267
5268 if (G1VerifyBitmaps) {
5269 MemRegion mr(hr->bottom(), hr->end());
5270 concurrent_mark()->clearRangePrevBitmap(mr);
5271 }
5272
5273 // Clear the card counts for this region.
5274 // Note: we only need to do this if the region is not young
5275 // (since we don't refine cards in young regions).
5276 if (!hr->is_young()) {
5277 _cg1r->hot_card_cache()->reset_card_counts(hr);
5278 }
5279 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5280 free_list->add_ordered(hr);
5281 }
5282
5283 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5284 FreeRegionList* free_list,
5285 bool par) {
5286 assert(hr->is_humongous(), "this is only for humongous regions");
5287 assert(free_list != NULL, "pre-condition");
5288 hr->clear_humongous();
5289 free_region(hr, free_list, par);
5290 }
5291
5292 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5293 const HeapRegionSetCount& humongous_regions_removed) {
5294 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5295 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5296 _old_set.bulk_remove(old_regions_removed);
5297 _humongous_set.bulk_remove(humongous_regions_removed);
5298 }
5299
5300 }
5301
5302 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5303 assert(list != NULL, "list can't be null");
5304 if (!list->is_empty()) {
5305 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5306 _hrm.insert_list_into_free_list(list);
5307 }
5308 }
5309
5310 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5311 decrease_used(bytes);
5312 }
5313
5314 class G1ParCleanupCTTask : public AbstractGangTask {
5315 G1SATBCardTableModRefBS* _ct_bs;
5316 G1CollectedHeap* _g1h;
5317 HeapRegion* volatile _su_head;
5318 public:
5319 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5320 G1CollectedHeap* g1h) :
5321 AbstractGangTask("G1 Par Cleanup CT Task"),
5322 _ct_bs(ct_bs), _g1h(g1h) { }
5323
5324 void work(uint worker_id) {
5325 HeapRegion* r;
5326 while (r = _g1h->pop_dirty_cards_region()) {
5327 clear_cards(r);
5328 }
5329 }
5330
5331 void clear_cards(HeapRegion* r) {
5332 // Cards of the survivors should have already been dirtied.
5333 if (!r->is_survivor()) {
5334 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5335 }
5336 }
5337 };
5338
5339 #ifndef PRODUCT
5340 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5341 G1CollectedHeap* _g1h;
5342 G1SATBCardTableModRefBS* _ct_bs;
5343 public:
5344 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5345 : _g1h(g1h), _ct_bs(ct_bs) { }
5346 virtual bool doHeapRegion(HeapRegion* r) {
5347 if (r->is_survivor()) {
5348 _g1h->verify_dirty_region(r);
5349 } else {
5350 _g1h->verify_not_dirty_region(r);
5351 }
5352 return false;
5353 }
5354 };
5355
5356 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5357 // All of the region should be clean.
5358 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5359 MemRegion mr(hr->bottom(), hr->end());
5360 ct_bs->verify_not_dirty_region(mr);
5361 }
5362
5363 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5364 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5365 // dirty allocated blocks as they allocate them. The thread that
5366 // retires each region and replaces it with a new one will do a
5367 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5368 // not dirty that area (one less thing to have to do while holding
5369 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5370 // is dirty.
5371 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5372 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5373 if (hr->is_young()) {
5374 ct_bs->verify_g1_young_region(mr);
5375 } else {
5376 ct_bs->verify_dirty_region(mr);
5377 }
5378 }
5379
5380 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5381 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5382 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5383 verify_dirty_region(hr);
5384 }
5385 }
5386
5387 void G1CollectedHeap::verify_dirty_young_regions() {
5388 verify_dirty_young_list(_young_list->first_region());
5389 }
5390
5391 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5392 HeapWord* tams, HeapWord* end) {
5393 guarantee(tams <= end,
5394 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5395 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5396 if (result < end) {
5397 gclog_or_tty->cr();
5398 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5399 bitmap_name, p2i(result));
5400 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5401 bitmap_name, p2i(tams), p2i(end));
5402 return false;
5403 }
5404 return true;
5405 }
5406
5407 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5408 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5409 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5410
5411 HeapWord* bottom = hr->bottom();
5412 HeapWord* ptams = hr->prev_top_at_mark_start();
5413 HeapWord* ntams = hr->next_top_at_mark_start();
5414 HeapWord* end = hr->end();
5415
5416 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5417
5418 bool res_n = true;
5419 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5420 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5421 // if we happen to be in that state.
5422 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5423 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5424 }
5425 if (!res_p || !res_n) {
5426 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5427 HR_FORMAT_PARAMS(hr));
5428 gclog_or_tty->print_cr("#### Caller: %s", caller);
5429 return false;
5430 }
5431 return true;
5432 }
5433
5434 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5435 if (!G1VerifyBitmaps) return;
5436
5437 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5438 }
5439
5440 class G1VerifyBitmapClosure : public HeapRegionClosure {
5441 private:
5442 const char* _caller;
5443 G1CollectedHeap* _g1h;
5444 bool _failures;
5445
5446 public:
5447 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5448 _caller(caller), _g1h(g1h), _failures(false) { }
5449
5450 bool failures() { return _failures; }
5451
5452 virtual bool doHeapRegion(HeapRegion* hr) {
5453 bool result = _g1h->verify_bitmaps(_caller, hr);
5454 if (!result) {
5455 _failures = true;
5456 }
5457 return false;
5458 }
5459 };
5460
5461 void G1CollectedHeap::check_bitmaps(const char* caller) {
5462 if (!G1VerifyBitmaps) return;
5463
5464 G1VerifyBitmapClosure cl(caller, this);
5465 heap_region_iterate(&cl);
5466 guarantee(!cl.failures(), "bitmap verification");
5467 }
5468
5469 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5470 private:
5471 bool _failures;
5472 public:
5473 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5474
5475 virtual bool doHeapRegion(HeapRegion* hr) {
5476 uint i = hr->hrm_index();
5477 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5478 if (hr->is_humongous()) {
5479 if (hr->in_collection_set()) {
5480 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5481 _failures = true;
5482 return true;
5483 }
5484 if (cset_state.is_in_cset()) {
5485 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5486 _failures = true;
5487 return true;
5488 }
5489 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5490 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5491 _failures = true;
5492 return true;
5493 }
5494 } else {
5495 if (cset_state.is_humongous()) {
5496 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5497 _failures = true;
5498 return true;
5499 }
5500 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5501 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5502 hr->in_collection_set(), cset_state.value(), i);
5503 _failures = true;
5504 return true;
5505 }
5506 if (cset_state.is_in_cset()) {
5507 if (hr->is_young() != (cset_state.is_young())) {
5508 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5509 hr->is_young(), cset_state.value(), i);
5510 _failures = true;
5511 return true;
5512 }
5513 if (hr->is_old() != (cset_state.is_old())) {
5514 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5515 hr->is_old(), cset_state.value(), i);
5516 _failures = true;
5517 return true;
5518 }
5519 }
5520 }
5521 return false;
5522 }
5523
5524 bool failures() const { return _failures; }
5525 };
5526
5527 bool G1CollectedHeap::check_cset_fast_test() {
5528 G1CheckCSetFastTableClosure cl;
5529 _hrm.iterate(&cl);
5530 return !cl.failures();
5531 }
5532 #endif // PRODUCT
5533
5534 void G1CollectedHeap::cleanUpCardTable() {
5535 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5536 double start = os::elapsedTime();
5537
5538 {
5539 // Iterate over the dirty cards region list.
5540 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5541
5542 workers()->run_task(&cleanup_task);
5543 #ifndef PRODUCT
5544 if (G1VerifyCTCleanup || VerifyAfterGC) {
5545 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5546 heap_region_iterate(&cleanup_verifier);
5547 }
5548 #endif
5549 }
5550
5551 double elapsed = os::elapsedTime() - start;
5552 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5553 }
5554
5555 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5556 size_t pre_used = 0;
5557 FreeRegionList local_free_list("Local List for CSet Freeing");
5558
5559 double young_time_ms = 0.0;
5560 double non_young_time_ms = 0.0;
5561
5562 // Since the collection set is a superset of the the young list,
5563 // all we need to do to clear the young list is clear its
5564 // head and length, and unlink any young regions in the code below
5565 _young_list->clear();
5566
5567 G1CollectorPolicy* policy = g1_policy();
5568
5569 double start_sec = os::elapsedTime();
5570 bool non_young = true;
5571
5572 HeapRegion* cur = cs_head;
5573 int age_bound = -1;
5574 size_t rs_lengths = 0;
5575
5576 while (cur != NULL) {
5577 assert(!is_on_master_free_list(cur), "sanity");
5578 if (non_young) {
5579 if (cur->is_young()) {
5580 double end_sec = os::elapsedTime();
5581 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5582 non_young_time_ms += elapsed_ms;
5583
5584 start_sec = os::elapsedTime();
5585 non_young = false;
5586 }
5587 } else {
5588 if (!cur->is_young()) {
5589 double end_sec = os::elapsedTime();
5590 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5591 young_time_ms += elapsed_ms;
5592
5593 start_sec = os::elapsedTime();
5594 non_young = true;
5595 }
5596 }
5597
5598 rs_lengths += cur->rem_set()->occupied_locked();
5599
5600 HeapRegion* next = cur->next_in_collection_set();
5601 assert(cur->in_collection_set(), "bad CS");
5602 cur->set_next_in_collection_set(NULL);
5603 clear_in_cset(cur);
5604
5605 if (cur->is_young()) {
5606 int index = cur->young_index_in_cset();
5607 assert(index != -1, "invariant");
5608 assert((uint) index < policy->young_cset_region_length(), "invariant");
5609 size_t words_survived = surviving_young_words[index];
5610 cur->record_surv_words_in_group(words_survived);
5611
5612 // At this point the we have 'popped' cur from the collection set
5613 // (linked via next_in_collection_set()) but it is still in the
5614 // young list (linked via next_young_region()). Clear the
5615 // _next_young_region field.
5616 cur->set_next_young_region(NULL);
5617 } else {
5618 int index = cur->young_index_in_cset();
5619 assert(index == -1, "invariant");
5620 }
5621
5622 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5623 (!cur->is_young() && cur->young_index_in_cset() == -1),
5624 "invariant" );
5625
5626 if (!cur->evacuation_failed()) {
5627 MemRegion used_mr = cur->used_region();
5628
5629 // And the region is empty.
5630 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5631 pre_used += cur->used();
5632 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5633 } else {
5634 cur->uninstall_surv_rate_group();
5635 if (cur->is_young()) {
5636 cur->set_young_index_in_cset(-1);
5637 }
5638 cur->set_evacuation_failed(false);
5639 // When moving a young gen region to old gen, we "allocate" that whole region
5640 // there. This is in addition to any already evacuated objects. Notify the
5641 // policy about that.
5642 // Old gen regions do not cause an additional allocation: both the objects
5643 // still in the region and the ones already moved are accounted for elsewhere.
5644 if (cur->is_young()) {
5645 policy->add_last_old_allocated_bytes(HeapRegion::GrainBytes);
5646 }
5647 // The region is now considered to be old.
5648 cur->set_old();
5649 // Do some allocation statistics accounting. Regions that failed evacuation
5650 // are always made old, so there is no need to update anything in the young
5651 // gen statistics, but we need to update old gen statistics.
5652 size_t used_words = cur->marked_bytes() / HeapWordSize;
5653 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5654 _old_set.add(cur);
5655 evacuation_info.increment_collectionset_used_after(cur->used());
5656 }
5657 cur = next;
5658 }
5659
5660 evacuation_info.set_regions_freed(local_free_list.length());
5661 policy->record_max_rs_lengths(rs_lengths);
5662 policy->cset_regions_freed();
5663
5664 double end_sec = os::elapsedTime();
5665 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5666
5667 if (non_young) {
5668 non_young_time_ms += elapsed_ms;
5669 } else {
5670 young_time_ms += elapsed_ms;
5671 }
5672
5673 prepend_to_freelist(&local_free_list);
5674 decrement_summary_bytes(pre_used);
5675 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5676 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5677 }
5678
5679 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5680 private:
5681 FreeRegionList* _free_region_list;
5682 HeapRegionSet* _proxy_set;
5683 HeapRegionSetCount _humongous_regions_removed;
5684 size_t _freed_bytes;
5685 public:
5686
5687 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5688 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5689 }
5690
5691 virtual bool doHeapRegion(HeapRegion* r) {
5692 if (!r->is_starts_humongous()) {
5693 return false;
5694 }
5695
5696 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5697
5698 oop obj = (oop)r->bottom();
5699 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5700
5701 // The following checks whether the humongous object is live are sufficient.
5702 // The main additional check (in addition to having a reference from the roots
5703 // or the young gen) is whether the humongous object has a remembered set entry.
5704 //
5705 // A humongous object cannot be live if there is no remembered set for it
5706 // because:
5707 // - there can be no references from within humongous starts regions referencing
5708 // the object because we never allocate other objects into them.
5709 // (I.e. there are no intra-region references that may be missed by the
5710 // remembered set)
5711 // - as soon there is a remembered set entry to the humongous starts region
5712 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5713 // until the end of a concurrent mark.
5714 //
5715 // It is not required to check whether the object has been found dead by marking
5716 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5717 // all objects allocated during that time are considered live.
5718 // SATB marking is even more conservative than the remembered set.
5719 // So if at this point in the collection there is no remembered set entry,
5720 // nobody has a reference to it.
5721 // At the start of collection we flush all refinement logs, and remembered sets
5722 // are completely up-to-date wrt to references to the humongous object.
5723 //
5724 // Other implementation considerations:
5725 // - never consider object arrays at this time because they would pose
5726 // considerable effort for cleaning up the the remembered sets. This is
5727 // required because stale remembered sets might reference locations that
5728 // are currently allocated into.
5729 uint region_idx = r->hrm_index();
5730 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5731 !r->rem_set()->is_empty()) {
5732
5733 if (G1TraceEagerReclaimHumongousObjects) {
5734 gclog_or_tty->print_cr("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",
5735 region_idx,
5736 (size_t)obj->size() * HeapWordSize,
5737 p2i(r->bottom()),
5738 r->rem_set()->occupied(),
5739 r->rem_set()->strong_code_roots_list_length(),
5740 next_bitmap->isMarked(r->bottom()),
5741 g1h->is_humongous_reclaim_candidate(region_idx),
5742 obj->is_typeArray()
5743 );
5744 }
5745
5746 return false;
5747 }
5748
5749 guarantee(obj->is_typeArray(),
5750 "Only eagerly reclaiming type arrays is supported, but the object "
5751 PTR_FORMAT " is not.", p2i(r->bottom()));
5752
5753 if (G1TraceEagerReclaimHumongousObjects) {
5754 gclog_or_tty->print_cr("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",
5755 region_idx,
5756 (size_t)obj->size() * HeapWordSize,
5757 p2i(r->bottom()),
5758 r->rem_set()->occupied(),
5759 r->rem_set()->strong_code_roots_list_length(),
5760 next_bitmap->isMarked(r->bottom()),
5761 g1h->is_humongous_reclaim_candidate(region_idx),
5762 obj->is_typeArray()
5763 );
5764 }
5765 // Need to clear mark bit of the humongous object if already set.
5766 if (next_bitmap->isMarked(r->bottom())) {
5767 next_bitmap->clear(r->bottom());
5768 }
5769 do {
5770 HeapRegion* next = g1h->next_region_in_humongous(r);
5771 _freed_bytes += r->used();
5772 r->set_containing_set(NULL);
5773 _humongous_regions_removed.increment(1u, r->capacity());
5774 g1h->free_humongous_region(r, _free_region_list, false);
5775 r = next;
5776 } while (r != NULL);
5777
5778 return false;
5779 }
5780
5781 HeapRegionSetCount& humongous_free_count() {
5782 return _humongous_regions_removed;
5783 }
5784
5785 size_t bytes_freed() const {
5786 return _freed_bytes;
5787 }
5788
5789 size_t humongous_reclaimed() const {
5790 return _humongous_regions_removed.length();
5791 }
5792 };
5793
5794 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5795 assert_at_safepoint(true);
5796
5797 if (!G1EagerReclaimHumongousObjects ||
5798 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5799 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5800 return;
5801 }
5802
5803 double start_time = os::elapsedTime();
5804
5805 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5806
5807 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5808 heap_region_iterate(&cl);
5809
5810 HeapRegionSetCount empty_set;
5811 remove_from_old_sets(empty_set, cl.humongous_free_count());
5812
5813 G1HRPrinter* hrp = hr_printer();
5814 if (hrp->is_active()) {
5815 FreeRegionListIterator iter(&local_cleanup_list);
5816 while (iter.more_available()) {
5817 HeapRegion* hr = iter.get_next();
5818 hrp->cleanup(hr);
5819 }
5820 }
5821
5822 prepend_to_freelist(&local_cleanup_list);
5823 decrement_summary_bytes(cl.bytes_freed());
5824
5825 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5826 cl.humongous_reclaimed());
5827 }
5828
5829 // This routine is similar to the above but does not record
5830 // any policy statistics or update free lists; we are abandoning
5831 // the current incremental collection set in preparation of a
5832 // full collection. After the full GC we will start to build up
5833 // the incremental collection set again.
5834 // This is only called when we're doing a full collection
5835 // and is immediately followed by the tearing down of the young list.
5836
5837 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5838 HeapRegion* cur = cs_head;
5839
5840 while (cur != NULL) {
5841 HeapRegion* next = cur->next_in_collection_set();
5842 assert(cur->in_collection_set(), "bad CS");
5843 cur->set_next_in_collection_set(NULL);
5844 clear_in_cset(cur);
5845 cur->set_young_index_in_cset(-1);
5846 cur = next;
5847 }
5848 }
5849
5850 void G1CollectedHeap::set_free_regions_coming() {
5851 if (G1ConcRegionFreeingVerbose) {
5852 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5853 "setting free regions coming");
5854 }
5855
5856 assert(!free_regions_coming(), "pre-condition");
5857 _free_regions_coming = true;
5858 }
5859
5860 void G1CollectedHeap::reset_free_regions_coming() {
5861 assert(free_regions_coming(), "pre-condition");
5862
5863 {
5864 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5865 _free_regions_coming = false;
5866 SecondaryFreeList_lock->notify_all();
5867 }
5868
5869 if (G1ConcRegionFreeingVerbose) {
5870 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5871 "reset free regions coming");
5872 }
5873 }
5874
5875 void G1CollectedHeap::wait_while_free_regions_coming() {
5876 // Most of the time we won't have to wait, so let's do a quick test
5877 // first before we take the lock.
5878 if (!free_regions_coming()) {
5879 return;
5880 }
5881
5882 if (G1ConcRegionFreeingVerbose) {
5883 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5884 "waiting for free regions");
5885 }
5886
5887 {
5888 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5889 while (free_regions_coming()) {
5890 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5891 }
5892 }
5893
5894 if (G1ConcRegionFreeingVerbose) {
5895 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5896 "done waiting for free regions");
5897 }
5898 }
5899
5900 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5901 return _allocator->is_retained_old_region(hr);
5902 }
5903
5904 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5905 _young_list->push_region(hr);
5906 }
5907
5908 class NoYoungRegionsClosure: public HeapRegionClosure {
5909 private:
5910 bool _success;
5911 public:
5912 NoYoungRegionsClosure() : _success(true) { }
5913 bool doHeapRegion(HeapRegion* r) {
5914 if (r->is_young()) {
5915 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5916 p2i(r->bottom()), p2i(r->end()));
5917 _success = false;
5918 }
5919 return false;
5920 }
5921 bool success() { return _success; }
5922 };
5923
5924 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5925 bool ret = _young_list->check_list_empty(check_sample);
5926
5927 if (check_heap) {
5928 NoYoungRegionsClosure closure;
5929 heap_region_iterate(&closure);
5930 ret = ret && closure.success();
5931 }
5932
5933 return ret;
5934 }
5935
5936 class TearDownRegionSetsClosure : public HeapRegionClosure {
5937 private:
5938 HeapRegionSet *_old_set;
5939
5940 public:
5941 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5942
5943 bool doHeapRegion(HeapRegion* r) {
5944 if (r->is_old()) {
5945 _old_set->remove(r);
5946 } else {
5947 // We ignore free regions, we'll empty the free list afterwards.
5948 // We ignore young regions, we'll empty the young list afterwards.
5949 // We ignore humongous regions, we're not tearing down the
5950 // humongous regions set.
5951 assert(r->is_free() || r->is_young() || r->is_humongous(),
5952 "it cannot be another type");
5953 }
5954 return false;
5955 }
5956
5957 ~TearDownRegionSetsClosure() {
5958 assert(_old_set->is_empty(), "post-condition");
5959 }
5960 };
5961
5962 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5963 assert_at_safepoint(true /* should_be_vm_thread */);
5964
5965 if (!free_list_only) {
5966 TearDownRegionSetsClosure cl(&_old_set);
5967 heap_region_iterate(&cl);
5968
5969 // Note that emptying the _young_list is postponed and instead done as
5970 // the first step when rebuilding the regions sets again. The reason for
5971 // this is that during a full GC string deduplication needs to know if
5972 // a collected region was young or old when the full GC was initiated.
5973 }
5974 _hrm.remove_all_free_regions();
5975 }
5976
5977 void G1CollectedHeap::increase_used(size_t bytes) {
5978 _summary_bytes_used += bytes;
5979 }
5980
5981 void G1CollectedHeap::decrease_used(size_t bytes) {
5982 assert(_summary_bytes_used >= bytes,
5983 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5984 _summary_bytes_used, bytes);
5985 _summary_bytes_used -= bytes;
5986 }
5987
5988 void G1CollectedHeap::set_used(size_t bytes) {
5989 _summary_bytes_used = bytes;
5990 }
5991
5992 class RebuildRegionSetsClosure : public HeapRegionClosure {
5993 private:
5994 bool _free_list_only;
5995 HeapRegionSet* _old_set;
5996 HeapRegionManager* _hrm;
5997 size_t _total_used;
5998
5999 public:
6000 RebuildRegionSetsClosure(bool free_list_only,
6001 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6002 _free_list_only(free_list_only),
6003 _old_set(old_set), _hrm(hrm), _total_used(0) {
6004 assert(_hrm->num_free_regions() == 0, "pre-condition");
6005 if (!free_list_only) {
6006 assert(_old_set->is_empty(), "pre-condition");
6007 }
6008 }
6009
6010 bool doHeapRegion(HeapRegion* r) {
6011 if (r->is_empty()) {
6012 // Add free regions to the free list
6013 r->set_free();
6014 r->set_allocation_context(AllocationContext::system());
6015 _hrm->insert_into_free_list(r);
6016 } else if (!_free_list_only) {
6017 assert(!r->is_young(), "we should not come across young regions");
6018
6019 if (r->is_humongous()) {
6020 // We ignore humongous regions. We left the humongous set unchanged.
6021 } else {
6022 // Objects that were compacted would have ended up on regions
6023 // that were previously old or free. Archive regions (which are
6024 // old) will not have been touched.
6025 assert(r->is_free() || r->is_old(), "invariant");
6026 // We now consider them old, so register as such. Leave
6027 // archive regions set that way, however, while still adding
6028 // them to the old set.
6029 if (!r->is_archive()) {
6030 r->set_old();
6031 }
6032 _old_set->add(r);
6033 }
6034 _total_used += r->used();
6035 }
6036
6037 return false;
6038 }
6039
6040 size_t total_used() {
6041 return _total_used;
6042 }
6043 };
6044
6045 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6046 assert_at_safepoint(true /* should_be_vm_thread */);
6047
6048 if (!free_list_only) {
6049 _young_list->empty_list();
6050 }
6051
6052 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6053 heap_region_iterate(&cl);
6054
6055 if (!free_list_only) {
6056 set_used(cl.total_used());
6057 if (_archive_allocator != NULL) {
6058 _archive_allocator->clear_used();
6059 }
6060 }
6061 assert(used_unlocked() == recalculate_used(),
6062 "inconsistent used_unlocked(), "
6063 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6064 used_unlocked(), recalculate_used());
6065 }
6066
6067 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6068 _refine_cte_cl->set_concurrent(concurrent);
6069 }
6070
6071 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6072 HeapRegion* hr = heap_region_containing(p);
6073 return hr->is_in(p);
6074 }
6075
6076 // Methods for the mutator alloc region
6077
6078 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6079 bool force) {
6080 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6081 assert(!force || g1_policy()->can_expand_young_list(),
6082 "if force is true we should be able to expand the young list");
6083 bool young_list_full = g1_policy()->is_young_list_full();
6084 if (force || !young_list_full) {
6085 HeapRegion* new_alloc_region = new_region(word_size,
6086 false /* is_old */,
6087 false /* do_expand */);
6088 if (new_alloc_region != NULL) {
6089 set_region_short_lived_locked(new_alloc_region);
6090 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6091 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6092 return new_alloc_region;
6093 }
6094 }
6095 return NULL;
6096 }
6097
6098 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6099 size_t allocated_bytes) {
6100 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6101 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6102
6103 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6104 increase_used(allocated_bytes);
6105 _hr_printer.retire(alloc_region);
6106 // We update the eden sizes here, when the region is retired,
6107 // instead of when it's allocated, since this is the point that its
6108 // used space has been recored in _summary_bytes_used.
6109 g1mm()->update_eden_size();
6110 }
6111
6112 // Methods for the GC alloc regions
6113
6114 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6115 uint count,
6116 InCSetState dest) {
6117 assert(FreeList_lock->owned_by_self(), "pre-condition");
6118
6119 if (count < g1_policy()->max_regions(dest)) {
6120 const bool is_survivor = (dest.is_young());
6121 HeapRegion* new_alloc_region = new_region(word_size,
6122 !is_survivor,
6123 true /* do_expand */);
6124 if (new_alloc_region != NULL) {
6125 // We really only need to do this for old regions given that we
6126 // should never scan survivors. But it doesn't hurt to do it
6127 // for survivors too.
6128 new_alloc_region->record_timestamp();
6129 if (is_survivor) {
6130 new_alloc_region->set_survivor();
6131 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6132 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6133 } else {
6134 new_alloc_region->set_old();
6135 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6136 check_bitmaps("Old Region Allocation", new_alloc_region);
6137 }
6138 bool during_im = collector_state()->during_initial_mark_pause();
6139 new_alloc_region->note_start_of_copying(during_im);
6140 return new_alloc_region;
6141 }
6142 }
6143 return NULL;
6144 }
6145
6146 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6147 size_t allocated_bytes,
6148 InCSetState dest) {
6149 bool during_im = collector_state()->during_initial_mark_pause();
6150 alloc_region->note_end_of_copying(during_im);
6151 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6152 if (dest.is_young()) {
6153 young_list()->add_survivor_region(alloc_region);
6154 } else {
6155 _old_set.add(alloc_region);
6156 }
6157 _hr_printer.retire(alloc_region);
6158 }
6159
6160 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6161 bool expanded = false;
6162 uint index = _hrm.find_highest_free(&expanded);
6163
6164 if (index != G1_NO_HRM_INDEX) {
6165 if (expanded) {
6166 ergo_verbose1(ErgoHeapSizing,
6167 "attempt heap expansion",
6168 ergo_format_reason("requested address range outside heap bounds")
6169 ergo_format_byte("region size"),
6170 HeapRegion::GrainWords * HeapWordSize);
6171 }
6172 _hrm.allocate_free_regions_starting_at(index, 1);
6173 return region_at(index);
6174 }
6175 return NULL;
6176 }
6177
6178 // Heap region set verification
6179
6180 class VerifyRegionListsClosure : public HeapRegionClosure {
6181 private:
6182 HeapRegionSet* _old_set;
6183 HeapRegionSet* _humongous_set;
6184 HeapRegionManager* _hrm;
6185
6186 public:
6187 HeapRegionSetCount _old_count;
6188 HeapRegionSetCount _humongous_count;
6189 HeapRegionSetCount _free_count;
6190
6191 VerifyRegionListsClosure(HeapRegionSet* old_set,
6192 HeapRegionSet* humongous_set,
6193 HeapRegionManager* hrm) :
6194 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6195 _old_count(), _humongous_count(), _free_count(){ }
6196
6197 bool doHeapRegion(HeapRegion* hr) {
6198 if (hr->is_young()) {
6199 // TODO
6200 } else if (hr->is_humongous()) {
6201 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6202 _humongous_count.increment(1u, hr->capacity());
6203 } else if (hr->is_empty()) {
6204 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6205 _free_count.increment(1u, hr->capacity());
6206 } else if (hr->is_old()) {
6207 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6208 _old_count.increment(1u, hr->capacity());
6209 } else {
6210 // There are no other valid region types. Check for one invalid
6211 // one we can identify: pinned without old or humongous set.
6212 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6213 ShouldNotReachHere();
6214 }
6215 return false;
6216 }
6217
6218 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6219 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6220 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6221 old_set->total_capacity_bytes(), _old_count.capacity());
6222
6223 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6224 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6225 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6226
6227 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());
6228 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6229 free_list->total_capacity_bytes(), _free_count.capacity());
6230 }
6231 };
6232
6233 void G1CollectedHeap::verify_region_sets() {
6234 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6235
6236 // First, check the explicit lists.
6237 _hrm.verify();
6238 {
6239 // Given that a concurrent operation might be adding regions to
6240 // the secondary free list we have to take the lock before
6241 // verifying it.
6242 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6243 _secondary_free_list.verify_list();
6244 }
6245
6246 // If a concurrent region freeing operation is in progress it will
6247 // be difficult to correctly attributed any free regions we come
6248 // across to the correct free list given that they might belong to
6249 // one of several (free_list, secondary_free_list, any local lists,
6250 // etc.). So, if that's the case we will skip the rest of the
6251 // verification operation. Alternatively, waiting for the concurrent
6252 // operation to complete will have a non-trivial effect on the GC's
6253 // operation (no concurrent operation will last longer than the
6254 // interval between two calls to verification) and it might hide
6255 // any issues that we would like to catch during testing.
6256 if (free_regions_coming()) {
6257 return;
6258 }
6259
6260 // Make sure we append the secondary_free_list on the free_list so
6261 // that all free regions we will come across can be safely
6262 // attributed to the free_list.
6263 append_secondary_free_list_if_not_empty_with_lock();
6264
6265 // Finally, make sure that the region accounting in the lists is
6266 // consistent with what we see in the heap.
6267
6268 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6269 heap_region_iterate(&cl);
6270 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6271 }
6272
6273 // Optimized nmethod scanning
6274
6275 class RegisterNMethodOopClosure: public OopClosure {
6276 G1CollectedHeap* _g1h;
6277 nmethod* _nm;
6278
6279 template <class T> void do_oop_work(T* p) {
6280 T heap_oop = oopDesc::load_heap_oop(p);
6281 if (!oopDesc::is_null(heap_oop)) {
6282 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6283 HeapRegion* hr = _g1h->heap_region_containing(obj);
6284 assert(!hr->is_continues_humongous(),
6285 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6286 " starting at " HR_FORMAT,
6287 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6288
6289 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6290 hr->add_strong_code_root_locked(_nm);
6291 }
6292 }
6293
6294 public:
6295 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6296 _g1h(g1h), _nm(nm) {}
6297
6298 void do_oop(oop* p) { do_oop_work(p); }
6299 void do_oop(narrowOop* p) { do_oop_work(p); }
6300 };
6301
6302 class UnregisterNMethodOopClosure: public OopClosure {
6303 G1CollectedHeap* _g1h;
6304 nmethod* _nm;
6305
6306 template <class T> void do_oop_work(T* p) {
6307 T heap_oop = oopDesc::load_heap_oop(p);
6308 if (!oopDesc::is_null(heap_oop)) {
6309 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6310 HeapRegion* hr = _g1h->heap_region_containing(obj);
6311 assert(!hr->is_continues_humongous(),
6312 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6313 " starting at " HR_FORMAT,
6314 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6315
6316 hr->remove_strong_code_root(_nm);
6317 }
6318 }
6319
6320 public:
6321 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6322 _g1h(g1h), _nm(nm) {}
6323
6324 void do_oop(oop* p) { do_oop_work(p); }
6325 void do_oop(narrowOop* p) { do_oop_work(p); }
6326 };
6327
6328 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6329 CollectedHeap::register_nmethod(nm);
6330
6331 guarantee(nm != NULL, "sanity");
6332 RegisterNMethodOopClosure reg_cl(this, nm);
6333 nm->oops_do(®_cl);
6334 }
6335
6336 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6337 CollectedHeap::unregister_nmethod(nm);
6338
6339 guarantee(nm != NULL, "sanity");
6340 UnregisterNMethodOopClosure reg_cl(this, nm);
6341 nm->oops_do(®_cl, true);
6342 }
6343
6344 void G1CollectedHeap::purge_code_root_memory() {
6345 double purge_start = os::elapsedTime();
6346 G1CodeRootSet::purge();
6347 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6348 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6349 }
6350
6351 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6352 G1CollectedHeap* _g1h;
6353
6354 public:
6355 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6356 _g1h(g1h) {}
6357
6358 void do_code_blob(CodeBlob* cb) {
6359 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6360 if (nm == NULL) {
6361 return;
6362 }
6363
6364 if (ScavengeRootsInCode) {
6365 _g1h->register_nmethod(nm);
6366 }
6367 }
6368 };
6369
6370 void G1CollectedHeap::rebuild_strong_code_roots() {
6371 RebuildStrongCodeRootClosure blob_cl(this);
6372 CodeCache::blobs_do(&blob_cl);
6373 }