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