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/g1EvacStats.inline.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_dirtied;
116 G1CollectedHeap* _g1h;
117 G1SATBCardTableLoggingModRefBS* _g1_bs;
118
119 HeapRegion* region_for_card(jbyte* card_ptr) const {
120 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
121 }
122
123 bool will_become_free(HeapRegion* hr) const {
124 // A region will be freed by free_collection_set if the region is in the
125 // collection set and has not had an evacuation failure.
126 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
127 }
128
129 public:
130 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
131 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
132
133 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
134 HeapRegion* hr = region_for_card(card_ptr);
135
136 // Should only dirty cards in regions that won't be freed.
137 if (!will_become_free(hr)) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_dirtied++;
140 }
141
142 return true;
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
160 {
161 // Claim the right to put the region on the dirty cards region list
162 // by installing a self pointer.
163 HeapRegion* next = hr->get_next_dirty_cards_region();
164 if (next == NULL) {
165 HeapRegion* res = (HeapRegion*)
166 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
167 NULL);
168 if (res == NULL) {
169 HeapRegion* head;
170 do {
171 // Put the region to the dirty cards region list.
172 head = _dirty_cards_region_list;
173 next = (HeapRegion*)
174 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
175 if (next == head) {
176 assert(hr->get_next_dirty_cards_region() == hr,
177 "hr->get_next_dirty_cards_region() != hr");
178 if (next == NULL) {
179 // The last region in the list points to itself.
180 hr->set_next_dirty_cards_region(hr);
181 } else {
182 hr->set_next_dirty_cards_region(next);
183 }
184 }
185 } while (next != head);
186 }
187 }
188 }
189
190 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
191 {
192 HeapRegion* head;
193 HeapRegion* hr;
194 do {
195 head = _dirty_cards_region_list;
196 if (head == NULL) {
197 return NULL;
198 }
199 HeapRegion* new_head = head->get_next_dirty_cards_region();
200 if (head == new_head) {
201 // The last region.
202 new_head = NULL;
203 }
204 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
205 head);
206 } while (hr != head);
207 assert(hr != NULL, "invariant");
208 hr->set_next_dirty_cards_region(NULL);
209 return hr;
210 }
211
212 // Returns true if the reference points to an object that
213 // can move in an incremental collection.
214 bool G1CollectedHeap::is_scavengable(const void* p) {
215 HeapRegion* hr = heap_region_containing(p);
216 return !hr->is_pinned();
217 }
218
219 // Private methods.
220
221 HeapRegion*
222 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
223 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
224 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
225 if (!_secondary_free_list.is_empty()) {
226 if (G1ConcRegionFreeingVerbose) {
227 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
228 "secondary_free_list has %u entries",
229 _secondary_free_list.length());
230 }
231 // It looks as if there are free regions available on the
232 // secondary_free_list. Let's move them to the free_list and try
233 // again to allocate from it.
234 append_secondary_free_list();
235
236 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
237 "empty we should have moved at least one entry to the free_list");
238 HeapRegion* res = _hrm.allocate_free_region(is_old);
239 if (G1ConcRegionFreeingVerbose) {
240 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
241 "allocated " HR_FORMAT " from secondary_free_list",
242 HR_FORMAT_PARAMS(res));
243 }
244 return res;
245 }
246
247 // Wait here until we get notified either when (a) there are no
248 // more free regions coming or (b) some regions have been moved on
249 // the secondary_free_list.
250 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
251 }
252
253 if (G1ConcRegionFreeingVerbose) {
254 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
255 "could not allocate from secondary_free_list");
256 }
257 return NULL;
258 }
259
260 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
261 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
262 "the only time we use this to allocate a humongous region is "
263 "when we are allocating a single humongous region");
264
265 HeapRegion* res;
266 if (G1StressConcRegionFreeing) {
267 if (!_secondary_free_list.is_empty()) {
268 if (G1ConcRegionFreeingVerbose) {
269 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
270 "forced to look at the secondary_free_list");
271 }
272 res = new_region_try_secondary_free_list(is_old);
273 if (res != NULL) {
274 return res;
275 }
276 }
277 }
278
279 res = _hrm.allocate_free_region(is_old);
280
281 if (res == NULL) {
282 if (G1ConcRegionFreeingVerbose) {
283 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
284 "res == NULL, trying the secondary_free_list");
285 }
286 res = new_region_try_secondary_free_list(is_old);
287 }
288 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
289 // Currently, only attempts to allocate GC alloc regions set
290 // do_expand to true. So, we should only reach here during a
291 // safepoint. If this assumption changes we might have to
292 // reconsider the use of _expand_heap_after_alloc_failure.
293 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
294
295 ergo_verbose1(ErgoHeapSizing,
296 "attempt heap expansion",
297 ergo_format_reason("region allocation request failed")
298 ergo_format_byte("allocation request"),
299 word_size * HeapWordSize);
300 if (expand(word_size * HeapWordSize)) {
301 // Given that expand() succeeded in expanding the heap, and we
302 // always expand the heap by an amount aligned to the heap
303 // region size, the free list should in theory not be empty.
304 // In either case allocate_free_region() will check for NULL.
305 res = _hrm.allocate_free_region(is_old);
306 } else {
307 _expand_heap_after_alloc_failure = false;
308 }
309 }
310 return res;
311 }
312
313 HeapWord*
314 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
315 uint num_regions,
316 size_t word_size,
317 AllocationContext_t context) {
318 assert(first != G1_NO_HRM_INDEX, "pre-condition");
319 assert(is_humongous(word_size), "word_size should be humongous");
320 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
321
322 // Index of last region in the series.
323 uint last = first + num_regions - 1;
324
325 // We need to initialize the region(s) we just discovered. This is
326 // a bit tricky given that it can happen concurrently with
327 // refinement threads refining cards on these regions and
328 // potentially wanting to refine the BOT as they are scanning
329 // those cards (this can happen shortly after a cleanup; see CR
330 // 6991377). So we have to set up the region(s) carefully and in
331 // a specific order.
332
333 // The word size sum of all the regions we will allocate.
334 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
335 assert(word_size <= word_size_sum, "sanity");
336
337 // This will be the "starts humongous" region.
338 HeapRegion* first_hr = region_at(first);
339 // The header of the new object will be placed at the bottom of
340 // the first region.
341 HeapWord* new_obj = first_hr->bottom();
342 // This will be the new top of the new object.
343 HeapWord* obj_top = new_obj + word_size;
344
345 // First, we need to zero the header of the space that we will be
346 // allocating. When we update top further down, some refinement
347 // threads might try to scan the region. By zeroing the header we
348 // ensure that any thread that will try to scan the region will
349 // come across the zero klass word and bail out.
350 //
351 // NOTE: It would not have been correct to have used
352 // CollectedHeap::fill_with_object() and make the space look like
353 // an int array. The thread that is doing the allocation will
354 // later update the object header to a potentially different array
355 // type and, for a very short period of time, the klass and length
356 // fields will be inconsistent. This could cause a refinement
357 // thread to calculate the object size incorrectly.
358 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
359
360 // How many words we use for filler objects.
361 size_t word_fill_size = word_size_sum - word_size;
362
363 // How many words memory we "waste" which cannot hold a filler object.
364 size_t words_not_fillable = 0;
365
366 if (word_fill_size >= min_fill_size()) {
367 fill_with_objects(obj_top, word_fill_size);
368 } else if (word_fill_size > 0) {
369 // We have space to fill, but we cannot fit an object there.
370 words_not_fillable = word_fill_size;
371 word_fill_size = 0;
372 }
373
374 // We will set up the first region as "starts humongous". This
375 // will also update the BOT covering all the regions to reflect
376 // that there is a single object that starts at the bottom of the
377 // first region.
378 first_hr->set_starts_humongous(obj_top, word_fill_size);
379 first_hr->set_allocation_context(context);
380 // Then, if there are any, we will set up the "continues
381 // humongous" regions.
382 HeapRegion* hr = NULL;
383 for (uint i = first + 1; i <= last; ++i) {
384 hr = region_at(i);
385 hr->set_continues_humongous(first_hr);
386 hr->set_allocation_context(context);
387 }
388
389 // Up to this point no concurrent thread would have been able to
390 // do any scanning on any region in this series. All the top
391 // fields still point to bottom, so the intersection between
392 // [bottom,top] and [card_start,card_end] will be empty. Before we
393 // update the top fields, we'll do a storestore to make sure that
394 // no thread sees the update to top before the zeroing of the
395 // object header and the BOT initialization.
396 OrderAccess::storestore();
397
398 // Now, we will update the top fields of the "continues humongous"
399 // regions except the last one.
400 for (uint i = first; i < last; ++i) {
401 hr = region_at(i);
402 hr->set_top(hr->end());
403 }
404
405 hr = region_at(last);
406 // If we cannot fit a filler object, we must set top to the end
407 // of the humongous object, otherwise we cannot iterate the heap
408 // and the BOT will not be complete.
409 hr->set_top(hr->end() - words_not_fillable);
410
411 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
412 "obj_top should be in last region");
413
414 check_bitmaps("Humongous Region Allocation", first_hr);
415
416 assert(words_not_fillable == 0 ||
417 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
418 "Miscalculation in humongous allocation");
419
420 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
421
422 for (uint i = first; i <= last; ++i) {
423 hr = region_at(i);
424 _humongous_set.add(hr);
425 if (i == first) {
426 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top());
427 } else {
428 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top());
429 }
430 }
431
432 return new_obj;
433 }
434
435 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
436 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
437 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
438 }
439
440 // If could fit into free regions w/o expansion, try.
441 // Otherwise, if can expand, do so.
442 // Otherwise, if using ex regions might help, try with ex given back.
443 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
444 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
445
446 verify_region_sets_optional();
447
448 uint first = G1_NO_HRM_INDEX;
449 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
450
451 if (obj_regions == 1) {
452 // Only one region to allocate, try to use a fast path by directly allocating
453 // from the free lists. Do not try to expand here, we will potentially do that
454 // later.
455 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
456 if (hr != NULL) {
457 first = hr->hrm_index();
458 }
459 } else {
460 // We can't allocate humongous regions spanning more than one region while
461 // cleanupComplete() is running, since some of the regions we find to be
462 // empty might not yet be added to the free list. It is not straightforward
463 // to know in which list they are on so that we can remove them. We only
464 // need to do this if we need to allocate more than one region to satisfy the
465 // current humongous allocation request. If we are only allocating one region
466 // we use the one-region region allocation code (see above), that already
467 // potentially waits for regions from the secondary free list.
468 wait_while_free_regions_coming();
469 append_secondary_free_list_if_not_empty_with_lock();
470
471 // Policy: Try only empty regions (i.e. already committed first). Maybe we
472 // are lucky enough to find some.
473 first = _hrm.find_contiguous_only_empty(obj_regions);
474 if (first != G1_NO_HRM_INDEX) {
475 _hrm.allocate_free_regions_starting_at(first, obj_regions);
476 }
477 }
478
479 if (first == G1_NO_HRM_INDEX) {
480 // Policy: We could not find enough regions for the humongous object in the
481 // free list. Look through the heap to find a mix of free and uncommitted regions.
482 // If so, try expansion.
483 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
484 if (first != G1_NO_HRM_INDEX) {
485 // We found something. Make sure these regions are committed, i.e. expand
486 // the heap. Alternatively we could do a defragmentation GC.
487 ergo_verbose1(ErgoHeapSizing,
488 "attempt heap expansion",
489 ergo_format_reason("humongous allocation request failed")
490 ergo_format_byte("allocation request"),
491 word_size * HeapWordSize);
492
493 _hrm.expand_at(first, obj_regions);
494 g1_policy()->record_new_heap_size(num_regions());
495
496 #ifdef ASSERT
497 for (uint i = first; i < first + obj_regions; ++i) {
498 HeapRegion* hr = region_at(i);
499 assert(hr->is_free(), "sanity");
500 assert(hr->is_empty(), "sanity");
501 assert(is_on_master_free_list(hr), "sanity");
502 }
503 #endif
504 _hrm.allocate_free_regions_starting_at(first, obj_regions);
505 } else {
506 // Policy: Potentially trigger a defragmentation GC.
507 }
508 }
509
510 HeapWord* result = NULL;
511 if (first != G1_NO_HRM_INDEX) {
512 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
513 word_size, context);
514 assert(result != NULL, "it should always return a valid result");
515
516 // A successful humongous object allocation changes the used space
517 // information of the old generation so we need to recalculate the
518 // sizes and update the jstat counters here.
519 g1mm()->update_sizes();
520 }
521
522 verify_region_sets_optional();
523
524 return result;
525 }
526
527 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
528 assert_heap_not_locked_and_not_at_safepoint();
529 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
530
531 uint dummy_gc_count_before;
532 uint dummy_gclocker_retry_count = 0;
533 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
534 }
535
536 HeapWord*
537 G1CollectedHeap::mem_allocate(size_t word_size,
538 bool* gc_overhead_limit_was_exceeded) {
539 assert_heap_not_locked_and_not_at_safepoint();
540
541 // Loop until the allocation is satisfied, or unsatisfied after GC.
542 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
543 uint gc_count_before;
544
545 HeapWord* result = NULL;
546 if (!is_humongous(word_size)) {
547 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
548 } else {
549 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
550 }
551 if (result != NULL) {
552 return result;
553 }
554
555 // Create the garbage collection operation...
556 VM_G1CollectForAllocation op(gc_count_before, word_size);
557 op.set_allocation_context(AllocationContext::current());
558
559 // ...and get the VM thread to execute it.
560 VMThread::execute(&op);
561
562 if (op.prologue_succeeded() && op.pause_succeeded()) {
563 // If the operation was successful we'll return the result even
564 // if it is NULL. If the allocation attempt failed immediately
565 // after a Full GC, it's unlikely we'll be able to allocate now.
566 HeapWord* result = op.result();
567 if (result != NULL && !is_humongous(word_size)) {
568 // Allocations that take place on VM operations do not do any
569 // card dirtying and we have to do it here. We only have to do
570 // this for non-humongous allocations, though.
571 dirty_young_block(result, word_size);
572 }
573 return result;
574 } else {
575 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
576 return NULL;
577 }
578 assert(op.result() == NULL,
579 "the result should be NULL if the VM op did not succeed");
580 }
581
582 // Give a warning if we seem to be looping forever.
583 if ((QueuedAllocationWarningCount > 0) &&
584 (try_count % QueuedAllocationWarningCount == 0)) {
585 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
586 }
587 }
588
589 ShouldNotReachHere();
590 return NULL;
591 }
592
593 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
594 AllocationContext_t context,
595 uint* gc_count_before_ret,
596 uint* gclocker_retry_count_ret) {
597 // Make sure you read the note in attempt_allocation_humongous().
598
599 assert_heap_not_locked_and_not_at_safepoint();
600 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
601 "be called for humongous allocation requests");
602
603 // We should only get here after the first-level allocation attempt
604 // (attempt_allocation()) failed to allocate.
605
606 // We will loop until a) we manage to successfully perform the
607 // allocation or b) we successfully schedule a collection which
608 // fails to perform the allocation. b) is the only case when we'll
609 // return NULL.
610 HeapWord* result = NULL;
611 for (int try_count = 1; /* we'll return */; try_count += 1) {
612 bool should_try_gc;
613 uint gc_count_before;
614
615 {
616 MutexLockerEx x(Heap_lock);
617 result = _allocator->attempt_allocation_locked(word_size, context);
618 if (result != NULL) {
619 return result;
620 }
621
622 if (GC_locker::is_active_and_needs_gc()) {
623 if (g1_policy()->can_expand_young_list()) {
624 // No need for an ergo verbose message here,
625 // can_expand_young_list() does this when it returns true.
626 result = _allocator->attempt_allocation_force(word_size, context);
627 if (result != NULL) {
628 return result;
629 }
630 }
631 should_try_gc = false;
632 } else {
633 // The GCLocker may not be active but the GCLocker initiated
634 // GC may not yet have been performed (GCLocker::needs_gc()
635 // returns true). In this case we do not try this GC and
636 // wait until the GCLocker initiated GC is performed, and
637 // then retry the allocation.
638 if (GC_locker::needs_gc()) {
639 should_try_gc = false;
640 } else {
641 // Read the GC count while still holding the Heap_lock.
642 gc_count_before = total_collections();
643 should_try_gc = true;
644 }
645 }
646 }
647
648 if (should_try_gc) {
649 bool succeeded;
650 result = do_collection_pause(word_size, gc_count_before, &succeeded,
651 GCCause::_g1_inc_collection_pause);
652 if (result != NULL) {
653 assert(succeeded, "only way to get back a non-NULL result");
654 return result;
655 }
656
657 if (succeeded) {
658 // If we get here we successfully scheduled a collection which
659 // failed to allocate. No point in trying to allocate
660 // further. We'll just return NULL.
661 MutexLockerEx x(Heap_lock);
662 *gc_count_before_ret = total_collections();
663 return NULL;
664 }
665 } else {
666 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
667 MutexLockerEx x(Heap_lock);
668 *gc_count_before_ret = total_collections();
669 return NULL;
670 }
671 // The GCLocker is either active or the GCLocker initiated
672 // GC has not yet been performed. Stall until it is and
673 // then retry the allocation.
674 GC_locker::stall_until_clear();
675 (*gclocker_retry_count_ret) += 1;
676 }
677
678 // We can reach here if we were unsuccessful in scheduling a
679 // collection (because another thread beat us to it) or if we were
680 // stalled due to the GC locker. In either can we should retry the
681 // allocation attempt in case another thread successfully
682 // performed a collection and reclaimed enough space. We do the
683 // first attempt (without holding the Heap_lock) here and the
684 // follow-on attempt will be at the start of the next loop
685 // iteration (after taking the Heap_lock).
686 result = _allocator->attempt_allocation(word_size, context);
687 if (result != NULL) {
688 return result;
689 }
690
691 // Give a warning if we seem to be looping forever.
692 if ((QueuedAllocationWarningCount > 0) &&
693 (try_count % QueuedAllocationWarningCount == 0)) {
694 warning("G1CollectedHeap::attempt_allocation_slow() "
695 "retries %d times", try_count);
696 }
697 }
698
699 ShouldNotReachHere();
700 return NULL;
701 }
702
703 void G1CollectedHeap::begin_archive_alloc_range() {
704 assert_at_safepoint(true /* should_be_vm_thread */);
705 if (_archive_allocator == NULL) {
706 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
707 }
708 }
709
710 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
711 // Allocations in archive regions cannot be of a size that would be considered
712 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
713 // may be different at archive-restore time.
714 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
715 }
716
717 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
718 assert_at_safepoint(true /* should_be_vm_thread */);
719 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
720 if (is_archive_alloc_too_large(word_size)) {
721 return NULL;
722 }
723 return _archive_allocator->archive_mem_allocate(word_size);
724 }
725
726 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
727 size_t end_alignment_in_bytes) {
728 assert_at_safepoint(true /* should_be_vm_thread */);
729 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
730
731 // Call complete_archive to do the real work, filling in the MemRegion
732 // array with the archive regions.
733 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
734 delete _archive_allocator;
735 _archive_allocator = NULL;
736 }
737
738 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
739 assert(ranges != NULL, "MemRegion array NULL");
740 assert(count != 0, "No MemRegions provided");
741 MemRegion reserved = _hrm.reserved();
742 for (size_t i = 0; i < count; i++) {
743 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
744 return false;
745 }
746 }
747 return true;
748 }
749
750 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
751 assert(!is_init_completed(), "Expect to be called at JVM init time");
752 assert(ranges != NULL, "MemRegion array NULL");
753 assert(count != 0, "No MemRegions provided");
754 MutexLockerEx x(Heap_lock);
755
756 MemRegion reserved = _hrm.reserved();
757 HeapWord* prev_last_addr = NULL;
758 HeapRegion* prev_last_region = NULL;
759
760 // Temporarily disable pretouching of heap pages. This interface is used
761 // when mmap'ing archived heap data in, so pre-touching is wasted.
762 FlagSetting fs(AlwaysPreTouch, false);
763
764 // Enable archive object checking in G1MarkSweep. We have to let it know
765 // about each archive range, so that objects in those ranges aren't marked.
766 G1MarkSweep::enable_archive_object_check();
767
768 // For each specified MemRegion range, allocate the corresponding G1
769 // regions and mark them as archive regions. We expect the ranges in
770 // ascending starting address order, without overlap.
771 for (size_t i = 0; i < count; i++) {
772 MemRegion curr_range = ranges[i];
773 HeapWord* start_address = curr_range.start();
774 size_t word_size = curr_range.word_size();
775 HeapWord* last_address = curr_range.last();
776 size_t commits = 0;
777
778 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
779 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
780 p2i(start_address), p2i(last_address));
781 guarantee(start_address > prev_last_addr,
782 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
783 p2i(start_address), p2i(prev_last_addr));
784 prev_last_addr = last_address;
785
786 // Check for ranges that start in the same G1 region in which the previous
787 // range ended, and adjust the start address so we don't try to allocate
788 // the same region again. If the current range is entirely within that
789 // region, skip it, just adjusting the recorded top.
790 HeapRegion* start_region = _hrm.addr_to_region(start_address);
791 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
792 start_address = start_region->end();
793 if (start_address > last_address) {
794 increase_used(word_size * HeapWordSize);
795 start_region->set_top(last_address + 1);
796 continue;
797 }
798 start_region->set_top(start_address);
799 curr_range = MemRegion(start_address, last_address + 1);
800 start_region = _hrm.addr_to_region(start_address);
801 }
802
803 // Perform the actual region allocation, exiting if it fails.
804 // Then note how much new space we have allocated.
805 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
806 return false;
807 }
808 increase_used(word_size * HeapWordSize);
809 if (commits != 0) {
810 ergo_verbose1(ErgoHeapSizing,
811 "attempt heap expansion",
812 ergo_format_reason("allocate archive regions")
813 ergo_format_byte("total size"),
814 HeapRegion::GrainWords * HeapWordSize * commits);
815 }
816
817 // Mark each G1 region touched by the range as archive, add it to the old set,
818 // and set the allocation context and top.
819 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
820 HeapRegion* last_region = _hrm.addr_to_region(last_address);
821 prev_last_region = last_region;
822
823 while (curr_region != NULL) {
824 assert(curr_region->is_empty() && !curr_region->is_pinned(),
825 "Region already in use (index %u)", curr_region->hrm_index());
826 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
827 curr_region->set_allocation_context(AllocationContext::system());
828 curr_region->set_archive();
829 _old_set.add(curr_region);
830 if (curr_region != last_region) {
831 curr_region->set_top(curr_region->end());
832 curr_region = _hrm.next_region_in_heap(curr_region);
833 } else {
834 curr_region->set_top(last_address + 1);
835 curr_region = NULL;
836 }
837 }
838
839 // Notify mark-sweep of the archive range.
840 G1MarkSweep::set_range_archive(curr_range, true);
841 }
842 return true;
843 }
844
845 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
846 assert(!is_init_completed(), "Expect to be called at JVM init time");
847 assert(ranges != NULL, "MemRegion array NULL");
848 assert(count != 0, "No MemRegions provided");
849 MemRegion reserved = _hrm.reserved();
850 HeapWord *prev_last_addr = NULL;
851 HeapRegion* prev_last_region = NULL;
852
853 // For each MemRegion, create filler objects, if needed, in the G1 regions
854 // that contain the address range. The address range actually within the
855 // MemRegion will not be modified. That is assumed to have been initialized
856 // elsewhere, probably via an mmap of archived heap data.
857 MutexLockerEx x(Heap_lock);
858 for (size_t i = 0; i < count; i++) {
859 HeapWord* start_address = ranges[i].start();
860 HeapWord* last_address = ranges[i].last();
861
862 assert(reserved.contains(start_address) && reserved.contains(last_address),
863 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
864 p2i(start_address), p2i(last_address));
865 assert(start_address > prev_last_addr,
866 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
867 p2i(start_address), p2i(prev_last_addr));
868
869 HeapRegion* start_region = _hrm.addr_to_region(start_address);
870 HeapRegion* last_region = _hrm.addr_to_region(last_address);
871 HeapWord* bottom_address = start_region->bottom();
872
873 // Check for a range beginning in the same region in which the
874 // previous one ended.
875 if (start_region == prev_last_region) {
876 bottom_address = prev_last_addr + 1;
877 }
878
879 // Verify that the regions were all marked as archive regions by
880 // alloc_archive_regions.
881 HeapRegion* curr_region = start_region;
882 while (curr_region != NULL) {
883 guarantee(curr_region->is_archive(),
884 "Expected archive region at index %u", curr_region->hrm_index());
885 if (curr_region != last_region) {
886 curr_region = _hrm.next_region_in_heap(curr_region);
887 } else {
888 curr_region = NULL;
889 }
890 }
891
892 prev_last_addr = last_address;
893 prev_last_region = last_region;
894
895 // Fill the memory below the allocated range with dummy object(s),
896 // if the region bottom does not match the range start, or if the previous
897 // range ended within the same G1 region, and there is a gap.
898 if (start_address != bottom_address) {
899 size_t fill_size = pointer_delta(start_address, bottom_address);
900 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
901 increase_used(fill_size * HeapWordSize);
902 }
903 }
904 }
905
906 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
907 uint* gc_count_before_ret,
908 uint* gclocker_retry_count_ret) {
909 assert_heap_not_locked_and_not_at_safepoint();
910 assert(!is_humongous(word_size), "attempt_allocation() should not "
911 "be called for humongous allocation requests");
912
913 AllocationContext_t context = AllocationContext::current();
914 HeapWord* result = _allocator->attempt_allocation(word_size, context);
915
916 if (result == NULL) {
917 result = attempt_allocation_slow(word_size,
918 context,
919 gc_count_before_ret,
920 gclocker_retry_count_ret);
921 }
922 assert_heap_not_locked();
923 if (result != NULL) {
924 dirty_young_block(result, word_size);
925 }
926 return result;
927 }
928
929 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
930 assert(!is_init_completed(), "Expect to be called at JVM init time");
931 assert(ranges != NULL, "MemRegion array NULL");
932 assert(count != 0, "No MemRegions provided");
933 MemRegion reserved = _hrm.reserved();
934 HeapWord* prev_last_addr = NULL;
935 HeapRegion* prev_last_region = NULL;
936 size_t size_used = 0;
937 size_t uncommitted_regions = 0;
938
939 // For each Memregion, free the G1 regions that constitute it, and
940 // notify mark-sweep that the range is no longer to be considered 'archive.'
941 MutexLockerEx x(Heap_lock);
942 for (size_t i = 0; i < count; i++) {
943 HeapWord* start_address = ranges[i].start();
944 HeapWord* last_address = ranges[i].last();
945
946 assert(reserved.contains(start_address) && reserved.contains(last_address),
947 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
948 p2i(start_address), p2i(last_address));
949 assert(start_address > prev_last_addr,
950 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
951 p2i(start_address), p2i(prev_last_addr));
952 size_used += ranges[i].byte_size();
953 prev_last_addr = last_address;
954
955 HeapRegion* start_region = _hrm.addr_to_region(start_address);
956 HeapRegion* last_region = _hrm.addr_to_region(last_address);
957
958 // Check for ranges that start in the same G1 region in which the previous
959 // range ended, and adjust the start address so we don't try to free
960 // the same region again. If the current range is entirely within that
961 // region, skip it.
962 if (start_region == prev_last_region) {
963 start_address = start_region->end();
964 if (start_address > last_address) {
965 continue;
966 }
967 start_region = _hrm.addr_to_region(start_address);
968 }
969 prev_last_region = last_region;
970
971 // After verifying that each region was marked as an archive region by
972 // alloc_archive_regions, set it free and empty and uncommit it.
973 HeapRegion* curr_region = start_region;
974 while (curr_region != NULL) {
975 guarantee(curr_region->is_archive(),
976 "Expected archive region at index %u", curr_region->hrm_index());
977 uint curr_index = curr_region->hrm_index();
978 _old_set.remove(curr_region);
979 curr_region->set_free();
980 curr_region->set_top(curr_region->bottom());
981 if (curr_region != last_region) {
982 curr_region = _hrm.next_region_in_heap(curr_region);
983 } else {
984 curr_region = NULL;
985 }
986 _hrm.shrink_at(curr_index, 1);
987 uncommitted_regions++;
988 }
989
990 // Notify mark-sweep that this is no longer an archive range.
991 G1MarkSweep::set_range_archive(ranges[i], false);
992 }
993
994 if (uncommitted_regions != 0) {
995 ergo_verbose1(ErgoHeapSizing,
996 "attempt heap shrinking",
997 ergo_format_reason("uncommitted archive regions")
998 ergo_format_byte("total size"),
999 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
1000 }
1001 decrease_used(size_used);
1002 }
1003
1004 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1005 uint* gc_count_before_ret,
1006 uint* gclocker_retry_count_ret) {
1007 // The structure of this method has a lot of similarities to
1008 // attempt_allocation_slow(). The reason these two were not merged
1009 // into a single one is that such a method would require several "if
1010 // allocation is not humongous do this, otherwise do that"
1011 // conditional paths which would obscure its flow. In fact, an early
1012 // version of this code did use a unified method which was harder to
1013 // follow and, as a result, it had subtle bugs that were hard to
1014 // track down. So keeping these two methods separate allows each to
1015 // be more readable. It will be good to keep these two in sync as
1016 // much as possible.
1017
1018 assert_heap_not_locked_and_not_at_safepoint();
1019 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1020 "should only be called for humongous allocations");
1021
1022 // Humongous objects can exhaust the heap quickly, so we should check if we
1023 // need to start a marking cycle at each humongous object allocation. We do
1024 // the check before we do the actual allocation. The reason for doing it
1025 // before the allocation is that we avoid having to keep track of the newly
1026 // allocated memory while we do a GC.
1027 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1028 word_size)) {
1029 collect(GCCause::_g1_humongous_allocation);
1030 }
1031
1032 // We will loop until a) we manage to successfully perform the
1033 // allocation or b) we successfully schedule a collection which
1034 // fails to perform the allocation. b) is the only case when we'll
1035 // return NULL.
1036 HeapWord* result = NULL;
1037 for (int try_count = 1; /* we'll return */; try_count += 1) {
1038 bool should_try_gc;
1039 uint gc_count_before;
1040
1041 {
1042 MutexLockerEx x(Heap_lock);
1043
1044 // Given that humongous objects are not allocated in young
1045 // regions, we'll first try to do the allocation without doing a
1046 // collection hoping that there's enough space in the heap.
1047 result = humongous_obj_allocate(word_size, AllocationContext::current());
1048 if (result != NULL) {
1049 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1050 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1051 return result;
1052 }
1053
1054 if (GC_locker::is_active_and_needs_gc()) {
1055 should_try_gc = false;
1056 } else {
1057 // The GCLocker may not be active but the GCLocker initiated
1058 // GC may not yet have been performed (GCLocker::needs_gc()
1059 // returns true). In this case we do not try this GC and
1060 // wait until the GCLocker initiated GC is performed, and
1061 // then retry the allocation.
1062 if (GC_locker::needs_gc()) {
1063 should_try_gc = false;
1064 } else {
1065 // Read the GC count while still holding the Heap_lock.
1066 gc_count_before = total_collections();
1067 should_try_gc = true;
1068 }
1069 }
1070 }
1071
1072 if (should_try_gc) {
1073 // If we failed to allocate the humongous object, we should try to
1074 // do a collection pause (if we're allowed) in case it reclaims
1075 // enough space for the allocation to succeed after the pause.
1076
1077 bool succeeded;
1078 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1079 GCCause::_g1_humongous_allocation);
1080 if (result != NULL) {
1081 assert(succeeded, "only way to get back a non-NULL result");
1082 return result;
1083 }
1084
1085 if (succeeded) {
1086 // If we get here we successfully scheduled a collection which
1087 // failed to allocate. No point in trying to allocate
1088 // further. We'll just return NULL.
1089 MutexLockerEx x(Heap_lock);
1090 *gc_count_before_ret = total_collections();
1091 return NULL;
1092 }
1093 } else {
1094 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1095 MutexLockerEx x(Heap_lock);
1096 *gc_count_before_ret = total_collections();
1097 return NULL;
1098 }
1099 // The GCLocker is either active or the GCLocker initiated
1100 // GC has not yet been performed. Stall until it is and
1101 // then retry the allocation.
1102 GC_locker::stall_until_clear();
1103 (*gclocker_retry_count_ret) += 1;
1104 }
1105
1106 // We can reach here if we were unsuccessful in scheduling a
1107 // collection (because another thread beat us to it) or if we were
1108 // stalled due to the GC locker. In either can we should retry the
1109 // allocation attempt in case another thread successfully
1110 // performed a collection and reclaimed enough space. Give a
1111 // warning if we seem to be looping forever.
1112
1113 if ((QueuedAllocationWarningCount > 0) &&
1114 (try_count % QueuedAllocationWarningCount == 0)) {
1115 warning("G1CollectedHeap::attempt_allocation_humongous() "
1116 "retries %d times", try_count);
1117 }
1118 }
1119
1120 ShouldNotReachHere();
1121 return NULL;
1122 }
1123
1124 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1125 AllocationContext_t context,
1126 bool expect_null_mutator_alloc_region) {
1127 assert_at_safepoint(true /* should_be_vm_thread */);
1128 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1129 "the current alloc region was unexpectedly found to be non-NULL");
1130
1131 if (!is_humongous(word_size)) {
1132 return _allocator->attempt_allocation_locked(word_size, context);
1133 } else {
1134 HeapWord* result = humongous_obj_allocate(word_size, context);
1135 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1136 collector_state()->set_initiate_conc_mark_if_possible(true);
1137 }
1138 return result;
1139 }
1140
1141 ShouldNotReachHere();
1142 }
1143
1144 class PostMCRemSetClearClosure: public HeapRegionClosure {
1145 G1CollectedHeap* _g1h;
1146 ModRefBarrierSet* _mr_bs;
1147 public:
1148 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1149 _g1h(g1h), _mr_bs(mr_bs) {}
1150
1151 bool doHeapRegion(HeapRegion* r) {
1152 HeapRegionRemSet* hrrs = r->rem_set();
1153
1154 _g1h->reset_gc_time_stamps(r);
1155
1156 if (r->is_continues_humongous()) {
1157 // We'll assert that the strong code root list and RSet is empty
1158 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1159 assert(hrrs->occupied() == 0, "RSet should be empty");
1160 } else {
1161 hrrs->clear();
1162 }
1163 // You might think here that we could clear just the cards
1164 // corresponding to the used region. But no: if we leave a dirty card
1165 // in a region we might allocate into, then it would prevent that card
1166 // from being enqueued, and cause it to be missed.
1167 // Re: the performance cost: we shouldn't be doing full GC anyway!
1168 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1169
1170 return false;
1171 }
1172 };
1173
1174 void G1CollectedHeap::clear_rsets_post_compaction() {
1175 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1176 heap_region_iterate(&rs_clear);
1177 }
1178
1179 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1180 G1CollectedHeap* _g1h;
1181 UpdateRSOopClosure _cl;
1182 public:
1183 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1184 _cl(g1->g1_rem_set(), worker_i),
1185 _g1h(g1)
1186 { }
1187
1188 bool doHeapRegion(HeapRegion* r) {
1189 if (!r->is_continues_humongous()) {
1190 _cl.set_from(r);
1191 r->oop_iterate(&_cl);
1192 }
1193 return false;
1194 }
1195 };
1196
1197 class ParRebuildRSTask: public AbstractGangTask {
1198 G1CollectedHeap* _g1;
1199 HeapRegionClaimer _hrclaimer;
1200
1201 public:
1202 ParRebuildRSTask(G1CollectedHeap* g1) :
1203 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1204
1205 void work(uint worker_id) {
1206 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1207 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1208 }
1209 };
1210
1211 class PostCompactionPrinterClosure: public HeapRegionClosure {
1212 private:
1213 G1HRPrinter* _hr_printer;
1214 public:
1215 bool doHeapRegion(HeapRegion* hr) {
1216 assert(!hr->is_young(), "not expecting to find young regions");
1217 if (hr->is_free()) {
1218 // We only generate output for non-empty regions.
1219 } else if (hr->is_starts_humongous()) {
1220 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1221 } else if (hr->is_continues_humongous()) {
1222 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1223 } else if (hr->is_archive()) {
1224 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1225 } else if (hr->is_old()) {
1226 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1227 } else {
1228 ShouldNotReachHere();
1229 }
1230 return false;
1231 }
1232
1233 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1234 : _hr_printer(hr_printer) { }
1235 };
1236
1237 void G1CollectedHeap::print_hrm_post_compaction() {
1238 PostCompactionPrinterClosure cl(hr_printer());
1239 heap_region_iterate(&cl);
1240 }
1241
1242 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1243 bool clear_all_soft_refs) {
1244 assert_at_safepoint(true /* should_be_vm_thread */);
1245
1246 if (GC_locker::check_active_before_gc()) {
1247 return false;
1248 }
1249
1250 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1251 gc_timer->register_gc_start();
1252
1253 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1254 GCIdMark gc_id_mark;
1255 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1256
1257 SvcGCMarker sgcm(SvcGCMarker::FULL);
1258 ResourceMark rm;
1259
1260 G1Log::update_level();
1261 print_heap_before_gc();
1262 trace_heap_before_gc(gc_tracer);
1263
1264 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1265
1266 verify_region_sets_optional();
1267
1268 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1269 collector_policy()->should_clear_all_soft_refs();
1270
1271 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1272
1273 {
1274 IsGCActiveMark x;
1275
1276 // Timing
1277 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1278 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1279
1280 {
1281 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1282 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1283 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1284
1285 g1_policy()->record_full_collection_start();
1286
1287 // Note: When we have a more flexible GC logging framework that
1288 // allows us to add optional attributes to a GC log record we
1289 // could consider timing and reporting how long we wait in the
1290 // following two methods.
1291 wait_while_free_regions_coming();
1292 // If we start the compaction before the CM threads finish
1293 // scanning the root regions we might trip them over as we'll
1294 // be moving objects / updating references. So let's wait until
1295 // they are done. By telling them to abort, they should complete
1296 // early.
1297 _cm->root_regions()->abort();
1298 _cm->root_regions()->wait_until_scan_finished();
1299 append_secondary_free_list_if_not_empty_with_lock();
1300
1301 gc_prologue(true);
1302 increment_total_collections(true /* full gc */);
1303 increment_old_marking_cycles_started();
1304
1305 assert(used() == recalculate_used(), "Should be equal");
1306
1307 verify_before_gc();
1308
1309 check_bitmaps("Full GC Start");
1310 pre_full_gc_dump(gc_timer);
1311
1312 #if defined(COMPILER2) || INCLUDE_JVMCI
1313 DerivedPointerTable::clear();
1314 #endif
1315
1316 // Disable discovery and empty the discovered lists
1317 // for the CM ref processor.
1318 ref_processor_cm()->disable_discovery();
1319 ref_processor_cm()->abandon_partial_discovery();
1320 ref_processor_cm()->verify_no_references_recorded();
1321
1322 // Abandon current iterations of concurrent marking and concurrent
1323 // refinement, if any are in progress. We have to do this before
1324 // wait_until_scan_finished() below.
1325 concurrent_mark()->abort();
1326
1327 // Make sure we'll choose a new allocation region afterwards.
1328 _allocator->release_mutator_alloc_region();
1329 _allocator->abandon_gc_alloc_regions();
1330 g1_rem_set()->cleanupHRRS();
1331
1332 // We should call this after we retire any currently active alloc
1333 // regions so that all the ALLOC / RETIRE events are generated
1334 // before the start GC event.
1335 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1336
1337 // We may have added regions to the current incremental collection
1338 // set between the last GC or pause and now. We need to clear the
1339 // incremental collection set and then start rebuilding it afresh
1340 // after this full GC.
1341 abandon_collection_set(g1_policy()->inc_cset_head());
1342 g1_policy()->clear_incremental_cset();
1343 g1_policy()->stop_incremental_cset_building();
1344
1345 tear_down_region_sets(false /* free_list_only */);
1346 collector_state()->set_gcs_are_young(true);
1347
1348 // See the comments in g1CollectedHeap.hpp and
1349 // G1CollectedHeap::ref_processing_init() about
1350 // how reference processing currently works in G1.
1351
1352 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1353 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1354
1355 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1356 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1357
1358 ref_processor_stw()->enable_discovery();
1359 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1360
1361 // Do collection work
1362 {
1363 HandleMark hm; // Discard invalid handles created during gc
1364 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1365 }
1366
1367 assert(num_free_regions() == 0, "we should not have added any free regions");
1368 rebuild_region_sets(false /* free_list_only */);
1369
1370 // Enqueue any discovered reference objects that have
1371 // not been removed from the discovered lists.
1372 ref_processor_stw()->enqueue_discovered_references();
1373
1374 #if defined(COMPILER2) || INCLUDE_JVMCI
1375 DerivedPointerTable::update_pointers();
1376 #endif
1377
1378 MemoryService::track_memory_usage();
1379
1380 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1381 ref_processor_stw()->verify_no_references_recorded();
1382
1383 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1384 ClassLoaderDataGraph::purge();
1385 MetaspaceAux::verify_metrics();
1386
1387 // Note: since we've just done a full GC, concurrent
1388 // marking is no longer active. Therefore we need not
1389 // re-enable reference discovery for the CM ref processor.
1390 // That will be done at the start of the next marking cycle.
1391 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1392 ref_processor_cm()->verify_no_references_recorded();
1393
1394 reset_gc_time_stamp();
1395 // Since everything potentially moved, we will clear all remembered
1396 // sets, and clear all cards. Later we will rebuild remembered
1397 // sets. We will also reset the GC time stamps of the regions.
1398 clear_rsets_post_compaction();
1399 check_gc_time_stamps();
1400
1401 resize_if_necessary_after_full_collection();
1402
1403 if (_hr_printer.is_active()) {
1404 // We should do this after we potentially resize the heap so
1405 // that all the COMMIT / UNCOMMIT events are generated before
1406 // the end GC event.
1407
1408 print_hrm_post_compaction();
1409 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1410 }
1411
1412 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1413 if (hot_card_cache->use_cache()) {
1414 hot_card_cache->reset_card_counts();
1415 hot_card_cache->reset_hot_cache();
1416 }
1417
1418 // Rebuild remembered sets of all regions.
1419 uint n_workers =
1420 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1421 workers()->active_workers(),
1422 Threads::number_of_non_daemon_threads());
1423 workers()->set_active_workers(n_workers);
1424
1425 ParRebuildRSTask rebuild_rs_task(this);
1426 workers()->run_task(&rebuild_rs_task);
1427
1428 // Rebuild the strong code root lists for each region
1429 rebuild_strong_code_roots();
1430
1431 if (true) { // FIXME
1432 MetaspaceGC::compute_new_size();
1433 }
1434
1435 #ifdef TRACESPINNING
1436 ParallelTaskTerminator::print_termination_counts();
1437 #endif
1438
1439 // Discard all rset updates
1440 JavaThread::dirty_card_queue_set().abandon_logs();
1441 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1442
1443 _young_list->reset_sampled_info();
1444 // At this point there should be no regions in the
1445 // entire heap tagged as young.
1446 assert(check_young_list_empty(true /* check_heap */),
1447 "young list should be empty at this point");
1448
1449 // Update the number of full collections that have been completed.
1450 increment_old_marking_cycles_completed(false /* concurrent */);
1451
1452 _hrm.verify_optional();
1453 verify_region_sets_optional();
1454
1455 verify_after_gc();
1456
1457 // Clear the previous marking bitmap, if needed for bitmap verification.
1458 // Note we cannot do this when we clear the next marking bitmap in
1459 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1460 // objects marked during a full GC against the previous bitmap.
1461 // But we need to clear it before calling check_bitmaps below since
1462 // the full GC has compacted objects and updated TAMS but not updated
1463 // the prev bitmap.
1464 if (G1VerifyBitmaps) {
1465 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1466 }
1467 check_bitmaps("Full GC End");
1468
1469 // Start a new incremental collection set for the next pause
1470 assert(g1_policy()->collection_set() == NULL, "must be");
1471 g1_policy()->start_incremental_cset_building();
1472
1473 clear_cset_fast_test();
1474
1475 _allocator->init_mutator_alloc_region();
1476
1477 g1_policy()->record_full_collection_end();
1478
1479 if (G1Log::fine()) {
1480 g1_policy()->print_heap_transition();
1481 }
1482
1483 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1484 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1485 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1486 // before any GC notifications are raised.
1487 g1mm()->update_sizes();
1488
1489 gc_epilogue(true);
1490 }
1491
1492 if (G1Log::finer()) {
1493 g1_policy()->print_detailed_heap_transition(true /* full */);
1494 }
1495
1496 print_heap_after_gc();
1497 trace_heap_after_gc(gc_tracer);
1498
1499 post_full_gc_dump(gc_timer);
1500
1501 gc_timer->register_gc_end();
1502 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1503 }
1504
1505 return true;
1506 }
1507
1508 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1509 // Currently, there is no facility in the do_full_collection(bool) API to notify
1510 // the caller that the collection did not succeed (e.g., because it was locked
1511 // out by the GC locker). So, right now, we'll ignore the return value.
1512 bool dummy = do_full_collection(true, /* explicit_gc */
1513 clear_all_soft_refs);
1514 }
1515
1516 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1517 // Include bytes that will be pre-allocated to support collections, as "used".
1518 const size_t used_after_gc = used();
1519 const size_t capacity_after_gc = capacity();
1520 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1521
1522 // This is enforced in arguments.cpp.
1523 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1524 "otherwise the code below doesn't make sense");
1525
1526 // We don't have floating point command-line arguments
1527 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1528 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1529 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1530 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1531
1532 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1533 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1534
1535 // We have to be careful here as these two calculations can overflow
1536 // 32-bit size_t's.
1537 double used_after_gc_d = (double) used_after_gc;
1538 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1539 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1540
1541 // Let's make sure that they are both under the max heap size, which
1542 // by default will make them fit into a size_t.
1543 double desired_capacity_upper_bound = (double) max_heap_size;
1544 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1545 desired_capacity_upper_bound);
1546 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1547 desired_capacity_upper_bound);
1548
1549 // We can now safely turn them into size_t's.
1550 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1551 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1552
1553 // This assert only makes sense here, before we adjust them
1554 // with respect to the min and max heap size.
1555 assert(minimum_desired_capacity <= maximum_desired_capacity,
1556 "minimum_desired_capacity = " SIZE_FORMAT ", "
1557 "maximum_desired_capacity = " SIZE_FORMAT,
1558 minimum_desired_capacity, maximum_desired_capacity);
1559
1560 // Should not be greater than the heap max size. No need to adjust
1561 // it with respect to the heap min size as it's a lower bound (i.e.,
1562 // we'll try to make the capacity larger than it, not smaller).
1563 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1564 // Should not be less than the heap min size. No need to adjust it
1565 // with respect to the heap max size as it's an upper bound (i.e.,
1566 // we'll try to make the capacity smaller than it, not greater).
1567 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1568
1569 if (capacity_after_gc < minimum_desired_capacity) {
1570 // Don't expand unless it's significant
1571 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1572 ergo_verbose4(ErgoHeapSizing,
1573 "attempt heap expansion",
1574 ergo_format_reason("capacity lower than "
1575 "min desired capacity after Full GC")
1576 ergo_format_byte("capacity")
1577 ergo_format_byte("occupancy")
1578 ergo_format_byte_perc("min desired capacity"),
1579 capacity_after_gc, used_after_gc,
1580 minimum_desired_capacity, (double) MinHeapFreeRatio);
1581 expand(expand_bytes);
1582
1583 // No expansion, now see if we want to shrink
1584 } else if (capacity_after_gc > maximum_desired_capacity) {
1585 // Capacity too large, compute shrinking size
1586 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1587 ergo_verbose4(ErgoHeapSizing,
1588 "attempt heap shrinking",
1589 ergo_format_reason("capacity higher than "
1590 "max desired capacity after Full GC")
1591 ergo_format_byte("capacity")
1592 ergo_format_byte("occupancy")
1593 ergo_format_byte_perc("max desired capacity"),
1594 capacity_after_gc, used_after_gc,
1595 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1596 shrink(shrink_bytes);
1597 }
1598 }
1599
1600 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1601 AllocationContext_t context,
1602 bool do_gc,
1603 bool clear_all_soft_refs,
1604 bool expect_null_mutator_alloc_region,
1605 bool* gc_succeeded) {
1606 *gc_succeeded = true;
1607 // Let's attempt the allocation first.
1608 HeapWord* result =
1609 attempt_allocation_at_safepoint(word_size,
1610 context,
1611 expect_null_mutator_alloc_region);
1612 if (result != NULL) {
1613 assert(*gc_succeeded, "sanity");
1614 return result;
1615 }
1616
1617 // In a G1 heap, we're supposed to keep allocation from failing by
1618 // incremental pauses. Therefore, at least for now, we'll favor
1619 // expansion over collection. (This might change in the future if we can
1620 // do something smarter than full collection to satisfy a failed alloc.)
1621 result = expand_and_allocate(word_size, context);
1622 if (result != NULL) {
1623 assert(*gc_succeeded, "sanity");
1624 return result;
1625 }
1626
1627 if (do_gc) {
1628 // Expansion didn't work, we'll try to do a Full GC.
1629 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1630 clear_all_soft_refs);
1631 }
1632
1633 return NULL;
1634 }
1635
1636 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1637 AllocationContext_t context,
1638 bool* succeeded) {
1639 assert_at_safepoint(true /* should_be_vm_thread */);
1640
1641 // Attempts to allocate followed by Full GC.
1642 HeapWord* result =
1643 satisfy_failed_allocation_helper(word_size,
1644 context,
1645 true, /* do_gc */
1646 false, /* clear_all_soft_refs */
1647 false, /* expect_null_mutator_alloc_region */
1648 succeeded);
1649
1650 if (result != NULL || !*succeeded) {
1651 return result;
1652 }
1653
1654 // Attempts to allocate followed by Full GC that will collect all soft references.
1655 result = satisfy_failed_allocation_helper(word_size,
1656 context,
1657 true, /* do_gc */
1658 true, /* clear_all_soft_refs */
1659 true, /* expect_null_mutator_alloc_region */
1660 succeeded);
1661
1662 if (result != NULL || !*succeeded) {
1663 return result;
1664 }
1665
1666 // Attempts to allocate, no GC
1667 result = satisfy_failed_allocation_helper(word_size,
1668 context,
1669 false, /* do_gc */
1670 false, /* clear_all_soft_refs */
1671 true, /* expect_null_mutator_alloc_region */
1672 succeeded);
1673
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 assert(!collector_policy()->should_clear_all_soft_refs(),
1680 "Flag should have been handled and cleared prior to this point");
1681
1682 // What else? We might try synchronous finalization later. If the total
1683 // space available is large enough for the allocation, then a more
1684 // complete compaction phase than we've tried so far might be
1685 // appropriate.
1686 assert(*succeeded, "sanity");
1687 return NULL;
1688 }
1689
1690 // Attempting to expand the heap sufficiently
1691 // to support an allocation of the given "word_size". If
1692 // successful, perform the allocation and return the address of the
1693 // allocated block, or else "NULL".
1694
1695 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1696 assert_at_safepoint(true /* should_be_vm_thread */);
1697
1698 verify_region_sets_optional();
1699
1700 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1701 ergo_verbose1(ErgoHeapSizing,
1702 "attempt heap expansion",
1703 ergo_format_reason("allocation request failed")
1704 ergo_format_byte("allocation request"),
1705 word_size * HeapWordSize);
1706 if (expand(expand_bytes)) {
1707 _hrm.verify_optional();
1708 verify_region_sets_optional();
1709 return attempt_allocation_at_safepoint(word_size,
1710 context,
1711 false /* expect_null_mutator_alloc_region */);
1712 }
1713 return NULL;
1714 }
1715
1716 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1717 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1718 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1719 HeapRegion::GrainBytes);
1720 ergo_verbose2(ErgoHeapSizing,
1721 "expand the heap",
1722 ergo_format_byte("requested expansion amount")
1723 ergo_format_byte("attempted expansion amount"),
1724 expand_bytes, aligned_expand_bytes);
1725
1726 if (is_maximal_no_gc()) {
1727 ergo_verbose0(ErgoHeapSizing,
1728 "did not expand the heap",
1729 ergo_format_reason("heap already fully expanded"));
1730 return false;
1731 }
1732
1733 double expand_heap_start_time_sec = os::elapsedTime();
1734 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1735 assert(regions_to_expand > 0, "Must expand by at least one region");
1736
1737 uint expanded_by = _hrm.expand_by(regions_to_expand);
1738 if (expand_time_ms != NULL) {
1739 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1740 }
1741
1742 if (expanded_by > 0) {
1743 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1744 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1745 g1_policy()->record_new_heap_size(num_regions());
1746 } else {
1747 ergo_verbose0(ErgoHeapSizing,
1748 "did not expand the heap",
1749 ergo_format_reason("heap expansion operation failed"));
1750 // The expansion of the virtual storage space was unsuccessful.
1751 // Let's see if it was because we ran out of swap.
1752 if (G1ExitOnExpansionFailure &&
1753 _hrm.available() >= regions_to_expand) {
1754 // We had head room...
1755 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1756 }
1757 }
1758 return regions_to_expand > 0;
1759 }
1760
1761 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1762 size_t aligned_shrink_bytes =
1763 ReservedSpace::page_align_size_down(shrink_bytes);
1764 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1765 HeapRegion::GrainBytes);
1766 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1767
1768 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1769 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1770
1771 ergo_verbose3(ErgoHeapSizing,
1772 "shrink the heap",
1773 ergo_format_byte("requested shrinking amount")
1774 ergo_format_byte("aligned shrinking amount")
1775 ergo_format_byte("attempted shrinking amount"),
1776 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1777 if (num_regions_removed > 0) {
1778 g1_policy()->record_new_heap_size(num_regions());
1779 } else {
1780 ergo_verbose0(ErgoHeapSizing,
1781 "did not shrink the heap",
1782 ergo_format_reason("heap shrinking operation failed"));
1783 }
1784 }
1785
1786 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1787 verify_region_sets_optional();
1788
1789 // We should only reach here at the end of a Full GC which means we
1790 // should not not be holding to any GC alloc regions. The method
1791 // below will make sure of that and do any remaining clean up.
1792 _allocator->abandon_gc_alloc_regions();
1793
1794 // Instead of tearing down / rebuilding the free lists here, we
1795 // could instead use the remove_all_pending() method on free_list to
1796 // remove only the ones that we need to remove.
1797 tear_down_region_sets(true /* free_list_only */);
1798 shrink_helper(shrink_bytes);
1799 rebuild_region_sets(true /* free_list_only */);
1800
1801 _hrm.verify_optional();
1802 verify_region_sets_optional();
1803 }
1804
1805 // Public methods.
1806
1807 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1808 CollectedHeap(),
1809 _g1_policy(policy_),
1810 _dirty_card_queue_set(false),
1811 _is_alive_closure_cm(this),
1812 _is_alive_closure_stw(this),
1813 _ref_processor_cm(NULL),
1814 _ref_processor_stw(NULL),
1815 _bot_shared(NULL),
1816 _cg1r(NULL),
1817 _g1mm(NULL),
1818 _refine_cte_cl(NULL),
1819 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1820 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1821 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1822 _humongous_reclaim_candidates(),
1823 _has_humongous_reclaim_candidates(false),
1824 _archive_allocator(NULL),
1825 _free_regions_coming(false),
1826 _young_list(new YoungList(this)),
1827 _gc_time_stamp(0),
1828 _summary_bytes_used(0),
1829 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1830 _old_evac_stats(OldPLABSize, PLABWeight),
1831 _expand_heap_after_alloc_failure(true),
1832 _old_marking_cycles_started(0),
1833 _old_marking_cycles_completed(0),
1834 _heap_summary_sent(false),
1835 _in_cset_fast_test(),
1836 _dirty_cards_region_list(NULL),
1837 _worker_cset_start_region(NULL),
1838 _worker_cset_start_region_time_stamp(NULL),
1839 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1840 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1841 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1842 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1843
1844 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1845 /* are_GC_task_threads */true,
1846 /* are_ConcurrentGC_threads */false);
1847 _workers->initialize_workers();
1848
1849 _allocator = G1Allocator::create_allocator(this);
1850 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1851
1852 // Override the default _filler_array_max_size so that no humongous filler
1853 // objects are created.
1854 _filler_array_max_size = _humongous_object_threshold_in_words;
1855
1856 uint n_queues = ParallelGCThreads;
1857 _task_queues = new RefToScanQueueSet(n_queues);
1858
1859 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1860 assert(n_rem_sets > 0, "Invariant.");
1861
1862 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1863 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1864 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1865
1866 for (uint i = 0; i < n_queues; i++) {
1867 RefToScanQueue* q = new RefToScanQueue();
1868 q->initialize();
1869 _task_queues->register_queue(i, q);
1870 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1871 }
1872 clear_cset_start_regions();
1873
1874 // Initialize the G1EvacuationFailureALot counters and flags.
1875 NOT_PRODUCT(reset_evacuation_should_fail();)
1876
1877 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1878 }
1879
1880 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1881 size_t size,
1882 size_t translation_factor) {
1883 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1884 // Allocate a new reserved space, preferring to use large pages.
1885 ReservedSpace rs(size, preferred_page_size);
1886 G1RegionToSpaceMapper* result =
1887 G1RegionToSpaceMapper::create_mapper(rs,
1888 size,
1889 rs.alignment(),
1890 HeapRegion::GrainBytes,
1891 translation_factor,
1892 mtGC);
1893 if (TracePageSizes) {
1894 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1895 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1896 }
1897 return result;
1898 }
1899
1900 jint G1CollectedHeap::initialize() {
1901 CollectedHeap::pre_initialize();
1902 os::enable_vtime();
1903
1904 G1Log::init();
1905
1906 // Necessary to satisfy locking discipline assertions.
1907
1908 MutexLocker x(Heap_lock);
1909
1910 // We have to initialize the printer before committing the heap, as
1911 // it will be used then.
1912 _hr_printer.set_active(G1PrintHeapRegions);
1913
1914 // While there are no constraints in the GC code that HeapWordSize
1915 // be any particular value, there are multiple other areas in the
1916 // system which believe this to be true (e.g. oop->object_size in some
1917 // cases incorrectly returns the size in wordSize units rather than
1918 // HeapWordSize).
1919 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1920
1921 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1922 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1923 size_t heap_alignment = collector_policy()->heap_alignment();
1924
1925 // Ensure that the sizes are properly aligned.
1926 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1927 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1928 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1929
1930 _refine_cte_cl = new RefineCardTableEntryClosure();
1931
1932 jint ecode = JNI_OK;
1933 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1934 if (_cg1r == NULL) {
1935 return ecode;
1936 }
1937
1938 // Reserve the maximum.
1939
1940 // When compressed oops are enabled, the preferred heap base
1941 // is calculated by subtracting the requested size from the
1942 // 32Gb boundary and using the result as the base address for
1943 // heap reservation. If the requested size is not aligned to
1944 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1945 // into the ReservedHeapSpace constructor) then the actual
1946 // base of the reserved heap may end up differing from the
1947 // address that was requested (i.e. the preferred heap base).
1948 // If this happens then we could end up using a non-optimal
1949 // compressed oops mode.
1950
1951 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1952 heap_alignment);
1953
1954 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1955
1956 // Create the barrier set for the entire reserved region.
1957 G1SATBCardTableLoggingModRefBS* bs
1958 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1959 bs->initialize();
1960 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1961 set_barrier_set(bs);
1962
1963 // Also create a G1 rem set.
1964 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1965
1966 // Carve out the G1 part of the heap.
1967
1968 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1969 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1970 G1RegionToSpaceMapper* heap_storage =
1971 G1RegionToSpaceMapper::create_mapper(g1_rs,
1972 g1_rs.size(),
1973 page_size,
1974 HeapRegion::GrainBytes,
1975 1,
1976 mtJavaHeap);
1977 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1978 max_byte_size, page_size,
1979 heap_rs.base(),
1980 heap_rs.size());
1981 heap_storage->set_mapping_changed_listener(&_listener);
1982
1983 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1984 G1RegionToSpaceMapper* bot_storage =
1985 create_aux_memory_mapper("Block offset table",
1986 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1987 G1BlockOffsetSharedArray::heap_map_factor());
1988
1989 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1990 G1RegionToSpaceMapper* cardtable_storage =
1991 create_aux_memory_mapper("Card table",
1992 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1993 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1994
1995 G1RegionToSpaceMapper* card_counts_storage =
1996 create_aux_memory_mapper("Card counts table",
1997 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1998 G1CardCounts::heap_map_factor());
1999
2000 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2001 G1RegionToSpaceMapper* prev_bitmap_storage =
2002 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2003 G1RegionToSpaceMapper* next_bitmap_storage =
2004 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2005
2006 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2007 g1_barrier_set()->initialize(cardtable_storage);
2008 // Do later initialization work for concurrent refinement.
2009 _cg1r->init(card_counts_storage);
2010
2011 // 6843694 - ensure that the maximum region index can fit
2012 // in the remembered set structures.
2013 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2014 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2015
2016 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2017 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2018 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2019 "too many cards per region");
2020
2021 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2022
2023 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2024
2025 {
2026 HeapWord* start = _hrm.reserved().start();
2027 HeapWord* end = _hrm.reserved().end();
2028 size_t granularity = HeapRegion::GrainBytes;
2029
2030 _in_cset_fast_test.initialize(start, end, granularity);
2031 _humongous_reclaim_candidates.initialize(start, end, granularity);
2032 }
2033
2034 // Create the ConcurrentMark data structure and thread.
2035 // (Must do this late, so that "max_regions" is defined.)
2036 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2037 if (_cm == NULL || !_cm->completed_initialization()) {
2038 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2039 return JNI_ENOMEM;
2040 }
2041 _cmThread = _cm->cmThread();
2042
2043 // Initialize the from_card cache structure of HeapRegionRemSet.
2044 HeapRegionRemSet::init_heap(max_regions());
2045
2046 // Now expand into the initial heap size.
2047 if (!expand(init_byte_size)) {
2048 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2049 return JNI_ENOMEM;
2050 }
2051
2052 // Perform any initialization actions delegated to the policy.
2053 g1_policy()->init();
2054
2055 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2056 SATB_Q_FL_lock,
2057 G1SATBProcessCompletedThreshold,
2058 Shared_SATB_Q_lock);
2059
2060 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2061 DirtyCardQ_CBL_mon,
2062 DirtyCardQ_FL_lock,
2063 concurrent_g1_refine()->yellow_zone(),
2064 concurrent_g1_refine()->red_zone(),
2065 Shared_DirtyCardQ_lock);
2066
2067 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2068 DirtyCardQ_CBL_mon,
2069 DirtyCardQ_FL_lock,
2070 -1, // never trigger processing
2071 -1, // no limit on length
2072 Shared_DirtyCardQ_lock,
2073 &JavaThread::dirty_card_queue_set());
2074
2075 // Here we allocate the dummy HeapRegion that is required by the
2076 // G1AllocRegion class.
2077 HeapRegion* dummy_region = _hrm.get_dummy_region();
2078
2079 // We'll re-use the same region whether the alloc region will
2080 // require BOT updates or not and, if it doesn't, then a non-young
2081 // region will complain that it cannot support allocations without
2082 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2083 dummy_region->set_eden();
2084 // Make sure it's full.
2085 dummy_region->set_top(dummy_region->end());
2086 G1AllocRegion::setup(this, dummy_region);
2087
2088 _allocator->init_mutator_alloc_region();
2089
2090 // Do create of the monitoring and management support so that
2091 // values in the heap have been properly initialized.
2092 _g1mm = new G1MonitoringSupport(this);
2093
2094 G1StringDedup::initialize();
2095
2096 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2097 for (uint i = 0; i < ParallelGCThreads; i++) {
2098 new (&_preserved_objs[i]) OopAndMarkOopStack();
2099 }
2100
2101 return JNI_OK;
2102 }
2103
2104 void G1CollectedHeap::stop() {
2105 // Stop all concurrent threads. We do this to make sure these threads
2106 // do not continue to execute and access resources (e.g. gclog_or_tty)
2107 // that are destroyed during shutdown.
2108 _cg1r->stop();
2109 _cmThread->stop();
2110 if (G1StringDedup::is_enabled()) {
2111 G1StringDedup::stop();
2112 }
2113 }
2114
2115 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2116 return HeapRegion::max_region_size();
2117 }
2118
2119 void G1CollectedHeap::post_initialize() {
2120 CollectedHeap::post_initialize();
2121 ref_processing_init();
2122 }
2123
2124 void G1CollectedHeap::ref_processing_init() {
2125 // Reference processing in G1 currently works as follows:
2126 //
2127 // * There are two reference processor instances. One is
2128 // used to record and process discovered references
2129 // during concurrent marking; the other is used to
2130 // record and process references during STW pauses
2131 // (both full and incremental).
2132 // * Both ref processors need to 'span' the entire heap as
2133 // the regions in the collection set may be dotted around.
2134 //
2135 // * For the concurrent marking ref processor:
2136 // * Reference discovery is enabled at initial marking.
2137 // * Reference discovery is disabled and the discovered
2138 // references processed etc during remarking.
2139 // * Reference discovery is MT (see below).
2140 // * Reference discovery requires a barrier (see below).
2141 // * Reference processing may or may not be MT
2142 // (depending on the value of ParallelRefProcEnabled
2143 // and ParallelGCThreads).
2144 // * A full GC disables reference discovery by the CM
2145 // ref processor and abandons any entries on it's
2146 // discovered lists.
2147 //
2148 // * For the STW processor:
2149 // * Non MT discovery is enabled at the start of a full GC.
2150 // * Processing and enqueueing during a full GC is non-MT.
2151 // * During a full GC, references are processed after marking.
2152 //
2153 // * Discovery (may or may not be MT) is enabled at the start
2154 // of an incremental evacuation pause.
2155 // * References are processed near the end of a STW evacuation pause.
2156 // * For both types of GC:
2157 // * Discovery is atomic - i.e. not concurrent.
2158 // * Reference discovery will not need a barrier.
2159
2160 MemRegion mr = reserved_region();
2161
2162 // Concurrent Mark ref processor
2163 _ref_processor_cm =
2164 new ReferenceProcessor(mr, // span
2165 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2166 // mt processing
2167 ParallelGCThreads,
2168 // degree of mt processing
2169 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2170 // mt discovery
2171 MAX2(ParallelGCThreads, ConcGCThreads),
2172 // degree of mt discovery
2173 false,
2174 // Reference discovery is not atomic
2175 &_is_alive_closure_cm);
2176 // is alive closure
2177 // (for efficiency/performance)
2178
2179 // STW ref processor
2180 _ref_processor_stw =
2181 new ReferenceProcessor(mr, // span
2182 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2183 // mt processing
2184 ParallelGCThreads,
2185 // degree of mt processing
2186 (ParallelGCThreads > 1),
2187 // mt discovery
2188 ParallelGCThreads,
2189 // degree of mt discovery
2190 true,
2191 // Reference discovery is atomic
2192 &_is_alive_closure_stw);
2193 // is alive closure
2194 // (for efficiency/performance)
2195 }
2196
2197 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2198 return g1_policy();
2199 }
2200
2201 size_t G1CollectedHeap::capacity() const {
2202 return _hrm.length() * HeapRegion::GrainBytes;
2203 }
2204
2205 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2206 hr->reset_gc_time_stamp();
2207 }
2208
2209 #ifndef PRODUCT
2210
2211 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2212 private:
2213 unsigned _gc_time_stamp;
2214 bool _failures;
2215
2216 public:
2217 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2218 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2219
2220 virtual bool doHeapRegion(HeapRegion* hr) {
2221 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2222 if (_gc_time_stamp != region_gc_time_stamp) {
2223 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2224 "expected %d", HR_FORMAT_PARAMS(hr),
2225 region_gc_time_stamp, _gc_time_stamp);
2226 _failures = true;
2227 }
2228 return false;
2229 }
2230
2231 bool failures() { return _failures; }
2232 };
2233
2234 void G1CollectedHeap::check_gc_time_stamps() {
2235 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2236 heap_region_iterate(&cl);
2237 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2238 }
2239 #endif // PRODUCT
2240
2241 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2242 _cg1r->hot_card_cache()->drain(cl, worker_i);
2243 }
2244
2245 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2246 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2247 size_t n_completed_buffers = 0;
2248 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2249 n_completed_buffers++;
2250 }
2251 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2252 dcqs.clear_n_completed_buffers();
2253 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2254 }
2255
2256 // Computes the sum of the storage used by the various regions.
2257 size_t G1CollectedHeap::used() const {
2258 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2259 if (_archive_allocator != NULL) {
2260 result += _archive_allocator->used();
2261 }
2262 return result;
2263 }
2264
2265 size_t G1CollectedHeap::used_unlocked() const {
2266 return _summary_bytes_used;
2267 }
2268
2269 class SumUsedClosure: public HeapRegionClosure {
2270 size_t _used;
2271 public:
2272 SumUsedClosure() : _used(0) {}
2273 bool doHeapRegion(HeapRegion* r) {
2274 _used += r->used();
2275 return false;
2276 }
2277 size_t result() { return _used; }
2278 };
2279
2280 size_t G1CollectedHeap::recalculate_used() const {
2281 double recalculate_used_start = os::elapsedTime();
2282
2283 SumUsedClosure blk;
2284 heap_region_iterate(&blk);
2285
2286 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2287 return blk.result();
2288 }
2289
2290 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2291 switch (cause) {
2292 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2293 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2294 case GCCause::_update_allocation_context_stats_inc: return true;
2295 case GCCause::_wb_conc_mark: return true;
2296 default : return false;
2297 }
2298 }
2299
2300 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2301 switch (cause) {
2302 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2303 case GCCause::_g1_humongous_allocation: return true;
2304 default: return is_user_requested_concurrent_full_gc(cause);
2305 }
2306 }
2307
2308 #ifndef PRODUCT
2309 void G1CollectedHeap::allocate_dummy_regions() {
2310 // Let's fill up most of the region
2311 size_t word_size = HeapRegion::GrainWords - 1024;
2312 // And as a result the region we'll allocate will be humongous.
2313 guarantee(is_humongous(word_size), "sanity");
2314
2315 // _filler_array_max_size is set to humongous object threshold
2316 // but temporarily change it to use CollectedHeap::fill_with_object().
2317 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2318
2319 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2320 // Let's use the existing mechanism for the allocation
2321 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2322 AllocationContext::system());
2323 if (dummy_obj != NULL) {
2324 MemRegion mr(dummy_obj, word_size);
2325 CollectedHeap::fill_with_object(mr);
2326 } else {
2327 // If we can't allocate once, we probably cannot allocate
2328 // again. Let's get out of the loop.
2329 break;
2330 }
2331 }
2332 }
2333 #endif // !PRODUCT
2334
2335 void G1CollectedHeap::increment_old_marking_cycles_started() {
2336 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2337 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2338 "Wrong marking cycle count (started: %d, completed: %d)",
2339 _old_marking_cycles_started, _old_marking_cycles_completed);
2340
2341 _old_marking_cycles_started++;
2342 }
2343
2344 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2345 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2346
2347 // We assume that if concurrent == true, then the caller is a
2348 // concurrent thread that was joined the Suspendible Thread
2349 // Set. If there's ever a cheap way to check this, we should add an
2350 // assert here.
2351
2352 // Given that this method is called at the end of a Full GC or of a
2353 // concurrent cycle, and those can be nested (i.e., a Full GC can
2354 // interrupt a concurrent cycle), the number of full collections
2355 // completed should be either one (in the case where there was no
2356 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2357 // behind the number of full collections started.
2358
2359 // This is the case for the inner caller, i.e. a Full GC.
2360 assert(concurrent ||
2361 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2362 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2363 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2364 "is inconsistent with _old_marking_cycles_completed = %u",
2365 _old_marking_cycles_started, _old_marking_cycles_completed);
2366
2367 // This is the case for the outer caller, i.e. the concurrent cycle.
2368 assert(!concurrent ||
2369 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2370 "for outer caller (concurrent cycle): "
2371 "_old_marking_cycles_started = %u "
2372 "is inconsistent with _old_marking_cycles_completed = %u",
2373 _old_marking_cycles_started, _old_marking_cycles_completed);
2374
2375 _old_marking_cycles_completed += 1;
2376
2377 // We need to clear the "in_progress" flag in the CM thread before
2378 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2379 // is set) so that if a waiter requests another System.gc() it doesn't
2380 // incorrectly see that a marking cycle is still in progress.
2381 if (concurrent) {
2382 _cmThread->set_idle();
2383 }
2384
2385 // This notify_all() will ensure that a thread that called
2386 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2387 // and it's waiting for a full GC to finish will be woken up. It is
2388 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2389 FullGCCount_lock->notify_all();
2390 }
2391
2392 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2393 GCIdMarkAndRestore conc_gc_id_mark;
2394 collector_state()->set_concurrent_cycle_started(true);
2395 _gc_timer_cm->register_gc_start(start_time);
2396
2397 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2398 trace_heap_before_gc(_gc_tracer_cm);
2399 _cmThread->set_gc_id(GCId::current());
2400 }
2401
2402 void G1CollectedHeap::register_concurrent_cycle_end() {
2403 if (collector_state()->concurrent_cycle_started()) {
2404 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2405 if (_cm->has_aborted()) {
2406 _gc_tracer_cm->report_concurrent_mode_failure();
2407 }
2408
2409 _gc_timer_cm->register_gc_end();
2410 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2411
2412 // Clear state variables to prepare for the next concurrent cycle.
2413 collector_state()->set_concurrent_cycle_started(false);
2414 _heap_summary_sent = false;
2415 }
2416 }
2417
2418 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2419 if (collector_state()->concurrent_cycle_started()) {
2420 // This function can be called when:
2421 // the cleanup pause is run
2422 // the concurrent cycle is aborted before the cleanup pause.
2423 // the concurrent cycle is aborted after the cleanup pause,
2424 // but before the concurrent cycle end has been registered.
2425 // Make sure that we only send the heap information once.
2426 if (!_heap_summary_sent) {
2427 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2428 trace_heap_after_gc(_gc_tracer_cm);
2429 _heap_summary_sent = true;
2430 }
2431 }
2432 }
2433
2434 void G1CollectedHeap::collect(GCCause::Cause cause) {
2435 assert_heap_not_locked();
2436
2437 uint gc_count_before;
2438 uint old_marking_count_before;
2439 uint full_gc_count_before;
2440 bool retry_gc;
2441
2442 do {
2443 retry_gc = false;
2444
2445 {
2446 MutexLocker ml(Heap_lock);
2447
2448 // Read the GC count while holding the Heap_lock
2449 gc_count_before = total_collections();
2450 full_gc_count_before = total_full_collections();
2451 old_marking_count_before = _old_marking_cycles_started;
2452 }
2453
2454 if (should_do_concurrent_full_gc(cause)) {
2455 // Schedule an initial-mark evacuation pause that will start a
2456 // concurrent cycle. We're setting word_size to 0 which means that
2457 // we are not requesting a post-GC allocation.
2458 VM_G1IncCollectionPause op(gc_count_before,
2459 0, /* word_size */
2460 true, /* should_initiate_conc_mark */
2461 g1_policy()->max_pause_time_ms(),
2462 cause);
2463 op.set_allocation_context(AllocationContext::current());
2464
2465 VMThread::execute(&op);
2466 if (!op.pause_succeeded()) {
2467 if (old_marking_count_before == _old_marking_cycles_started) {
2468 retry_gc = op.should_retry_gc();
2469 } else {
2470 // A Full GC happened while we were trying to schedule the
2471 // initial-mark GC. No point in starting a new cycle given
2472 // that the whole heap was collected anyway.
2473 }
2474
2475 if (retry_gc) {
2476 if (GC_locker::is_active_and_needs_gc()) {
2477 GC_locker::stall_until_clear();
2478 }
2479 }
2480 }
2481 } else {
2482 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2483 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2484
2485 // Schedule a standard evacuation pause. We're setting word_size
2486 // to 0 which means that we are not requesting a post-GC allocation.
2487 VM_G1IncCollectionPause op(gc_count_before,
2488 0, /* word_size */
2489 false, /* should_initiate_conc_mark */
2490 g1_policy()->max_pause_time_ms(),
2491 cause);
2492 VMThread::execute(&op);
2493 } else {
2494 // Schedule a Full GC.
2495 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2496 VMThread::execute(&op);
2497 }
2498 }
2499 } while (retry_gc);
2500 }
2501
2502 bool G1CollectedHeap::is_in(const void* p) const {
2503 if (_hrm.reserved().contains(p)) {
2504 // Given that we know that p is in the reserved space,
2505 // heap_region_containing() should successfully
2506 // return the containing region.
2507 HeapRegion* hr = heap_region_containing(p);
2508 return hr->is_in(p);
2509 } else {
2510 return false;
2511 }
2512 }
2513
2514 #ifdef ASSERT
2515 bool G1CollectedHeap::is_in_exact(const void* p) const {
2516 bool contains = reserved_region().contains(p);
2517 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2518 if (contains && available) {
2519 return true;
2520 } else {
2521 return false;
2522 }
2523 }
2524 #endif
2525
2526 bool G1CollectedHeap::obj_in_cs(oop obj) {
2527 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2528 return r != NULL && r->in_collection_set();
2529 }
2530
2531 // Iteration functions.
2532
2533 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2534
2535 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2536 ExtendedOopClosure* _cl;
2537 public:
2538 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2539 bool doHeapRegion(HeapRegion* r) {
2540 if (!r->is_continues_humongous()) {
2541 r->oop_iterate(_cl);
2542 }
2543 return false;
2544 }
2545 };
2546
2547 // Iterates an ObjectClosure over all objects within a HeapRegion.
2548
2549 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2550 ObjectClosure* _cl;
2551 public:
2552 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2553 bool doHeapRegion(HeapRegion* r) {
2554 if (!r->is_continues_humongous()) {
2555 r->object_iterate(_cl);
2556 }
2557 return false;
2558 }
2559 };
2560
2561 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2562 IterateObjectClosureRegionClosure blk(cl);
2563 heap_region_iterate(&blk);
2564 }
2565
2566 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2567 _hrm.iterate(cl);
2568 }
2569
2570 void
2571 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2572 uint worker_id,
2573 HeapRegionClaimer *hrclaimer,
2574 bool concurrent) const {
2575 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2576 }
2577
2578 // Clear the cached CSet starting regions and (more importantly)
2579 // the time stamps. Called when we reset the GC time stamp.
2580 void G1CollectedHeap::clear_cset_start_regions() {
2581 assert(_worker_cset_start_region != NULL, "sanity");
2582 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2583
2584 for (uint i = 0; i < ParallelGCThreads; i++) {
2585 _worker_cset_start_region[i] = NULL;
2586 _worker_cset_start_region_time_stamp[i] = 0;
2587 }
2588 }
2589
2590 // Given the id of a worker, obtain or calculate a suitable
2591 // starting region for iterating over the current collection set.
2592 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2593 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2594
2595 HeapRegion* result = NULL;
2596 unsigned gc_time_stamp = get_gc_time_stamp();
2597
2598 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2599 // Cached starting region for current worker was set
2600 // during the current pause - so it's valid.
2601 // Note: the cached starting heap region may be NULL
2602 // (when the collection set is empty).
2603 result = _worker_cset_start_region[worker_i];
2604 assert(result == NULL || result->in_collection_set(), "sanity");
2605 return result;
2606 }
2607
2608 // The cached entry was not valid so let's calculate
2609 // a suitable starting heap region for this worker.
2610
2611 // We want the parallel threads to start their collection
2612 // set iteration at different collection set regions to
2613 // avoid contention.
2614 // If we have:
2615 // n collection set regions
2616 // p threads
2617 // Then thread t will start at region floor ((t * n) / p)
2618
2619 result = g1_policy()->collection_set();
2620 uint cs_size = g1_policy()->cset_region_length();
2621 uint active_workers = workers()->active_workers();
2622
2623 uint end_ind = (cs_size * worker_i) / active_workers;
2624 uint start_ind = 0;
2625
2626 if (worker_i > 0 &&
2627 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2628 // Previous workers starting region is valid
2629 // so let's iterate from there
2630 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2631 result = _worker_cset_start_region[worker_i - 1];
2632 }
2633
2634 for (uint i = start_ind; i < end_ind; i++) {
2635 result = result->next_in_collection_set();
2636 }
2637
2638 // Note: the calculated starting heap region may be NULL
2639 // (when the collection set is empty).
2640 assert(result == NULL || result->in_collection_set(), "sanity");
2641 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2642 "should be updated only once per pause");
2643 _worker_cset_start_region[worker_i] = result;
2644 OrderAccess::storestore();
2645 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2646 return result;
2647 }
2648
2649 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2650 HeapRegion* r = g1_policy()->collection_set();
2651 while (r != NULL) {
2652 HeapRegion* next = r->next_in_collection_set();
2653 if (cl->doHeapRegion(r)) {
2654 cl->incomplete();
2655 return;
2656 }
2657 r = next;
2658 }
2659 }
2660
2661 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2662 HeapRegionClosure *cl) {
2663 if (r == NULL) {
2664 // The CSet is empty so there's nothing to do.
2665 return;
2666 }
2667
2668 assert(r->in_collection_set(),
2669 "Start region must be a member of the collection set.");
2670 HeapRegion* cur = r;
2671 while (cur != NULL) {
2672 HeapRegion* next = cur->next_in_collection_set();
2673 if (cl->doHeapRegion(cur) && false) {
2674 cl->incomplete();
2675 return;
2676 }
2677 cur = next;
2678 }
2679 cur = g1_policy()->collection_set();
2680 while (cur != r) {
2681 HeapRegion* next = cur->next_in_collection_set();
2682 if (cl->doHeapRegion(cur) && false) {
2683 cl->incomplete();
2684 return;
2685 }
2686 cur = next;
2687 }
2688 }
2689
2690 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2691 HeapRegion* result = _hrm.next_region_in_heap(from);
2692 while (result != NULL && result->is_pinned()) {
2693 result = _hrm.next_region_in_heap(result);
2694 }
2695 return result;
2696 }
2697
2698 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2699 HeapRegion* hr = heap_region_containing(addr);
2700 return hr->block_start(addr);
2701 }
2702
2703 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2704 HeapRegion* hr = heap_region_containing(addr);
2705 return hr->block_size(addr);
2706 }
2707
2708 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2709 HeapRegion* hr = heap_region_containing(addr);
2710 return hr->block_is_obj(addr);
2711 }
2712
2713 bool G1CollectedHeap::supports_tlab_allocation() const {
2714 return true;
2715 }
2716
2717 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2718 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2719 }
2720
2721 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2722 return young_list()->eden_used_bytes();
2723 }
2724
2725 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2726 // must be equal to the humongous object limit.
2727 size_t G1CollectedHeap::max_tlab_size() const {
2728 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2729 }
2730
2731 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2732 AllocationContext_t context = AllocationContext::current();
2733 return _allocator->unsafe_max_tlab_alloc(context);
2734 }
2735
2736 size_t G1CollectedHeap::max_capacity() const {
2737 return _hrm.reserved().byte_size();
2738 }
2739
2740 jlong G1CollectedHeap::millis_since_last_gc() {
2741 // assert(false, "NYI");
2742 return 0;
2743 }
2744
2745 void G1CollectedHeap::prepare_for_verify() {
2746 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2747 ensure_parsability(false);
2748 }
2749 g1_rem_set()->prepare_for_verify();
2750 }
2751
2752 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2753 VerifyOption vo) {
2754 switch (vo) {
2755 case VerifyOption_G1UsePrevMarking:
2756 return hr->obj_allocated_since_prev_marking(obj);
2757 case VerifyOption_G1UseNextMarking:
2758 return hr->obj_allocated_since_next_marking(obj);
2759 case VerifyOption_G1UseMarkWord:
2760 return false;
2761 default:
2762 ShouldNotReachHere();
2763 }
2764 return false; // keep some compilers happy
2765 }
2766
2767 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2768 switch (vo) {
2769 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2770 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2771 case VerifyOption_G1UseMarkWord: return NULL;
2772 default: ShouldNotReachHere();
2773 }
2774 return NULL; // keep some compilers happy
2775 }
2776
2777 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2778 switch (vo) {
2779 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2780 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2781 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2782 default: ShouldNotReachHere();
2783 }
2784 return false; // keep some compilers happy
2785 }
2786
2787 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2788 switch (vo) {
2789 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2790 case VerifyOption_G1UseNextMarking: return "NTAMS";
2791 case VerifyOption_G1UseMarkWord: return "NONE";
2792 default: ShouldNotReachHere();
2793 }
2794 return NULL; // keep some compilers happy
2795 }
2796
2797 class VerifyRootsClosure: public OopClosure {
2798 private:
2799 G1CollectedHeap* _g1h;
2800 VerifyOption _vo;
2801 bool _failures;
2802 public:
2803 // _vo == UsePrevMarking -> use "prev" marking information,
2804 // _vo == UseNextMarking -> use "next" marking information,
2805 // _vo == UseMarkWord -> use mark word from object header.
2806 VerifyRootsClosure(VerifyOption vo) :
2807 _g1h(G1CollectedHeap::heap()),
2808 _vo(vo),
2809 _failures(false) { }
2810
2811 bool failures() { return _failures; }
2812
2813 template <class T> void do_oop_nv(T* p) {
2814 T heap_oop = oopDesc::load_heap_oop(p);
2815 if (!oopDesc::is_null(heap_oop)) {
2816 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2817 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2818 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2819 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2820 if (_vo == VerifyOption_G1UseMarkWord) {
2821 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2822 }
2823 obj->print_on(gclog_or_tty);
2824 _failures = true;
2825 }
2826 }
2827 }
2828
2829 void do_oop(oop* p) { do_oop_nv(p); }
2830 void do_oop(narrowOop* p) { do_oop_nv(p); }
2831 };
2832
2833 class G1VerifyCodeRootOopClosure: public OopClosure {
2834 G1CollectedHeap* _g1h;
2835 OopClosure* _root_cl;
2836 nmethod* _nm;
2837 VerifyOption _vo;
2838 bool _failures;
2839
2840 template <class T> void do_oop_work(T* p) {
2841 // First verify that this root is live
2842 _root_cl->do_oop(p);
2843
2844 if (!G1VerifyHeapRegionCodeRoots) {
2845 // We're not verifying the code roots attached to heap region.
2846 return;
2847 }
2848
2849 // Don't check the code roots during marking verification in a full GC
2850 if (_vo == VerifyOption_G1UseMarkWord) {
2851 return;
2852 }
2853
2854 // Now verify that the current nmethod (which contains p) is
2855 // in the code root list of the heap region containing the
2856 // object referenced by p.
2857
2858 T heap_oop = oopDesc::load_heap_oop(p);
2859 if (!oopDesc::is_null(heap_oop)) {
2860 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2861
2862 // Now fetch the region containing the object
2863 HeapRegion* hr = _g1h->heap_region_containing(obj);
2864 HeapRegionRemSet* hrrs = hr->rem_set();
2865 // Verify that the strong code root list for this region
2866 // contains the nmethod
2867 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2868 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2869 "from nmethod " PTR_FORMAT " not in strong "
2870 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2871 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2872 _failures = true;
2873 }
2874 }
2875 }
2876
2877 public:
2878 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2879 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2880
2881 void do_oop(oop* p) { do_oop_work(p); }
2882 void do_oop(narrowOop* p) { do_oop_work(p); }
2883
2884 void set_nmethod(nmethod* nm) { _nm = nm; }
2885 bool failures() { return _failures; }
2886 };
2887
2888 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2889 G1VerifyCodeRootOopClosure* _oop_cl;
2890
2891 public:
2892 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2893 _oop_cl(oop_cl) {}
2894
2895 void do_code_blob(CodeBlob* cb) {
2896 nmethod* nm = cb->as_nmethod_or_null();
2897 if (nm != NULL) {
2898 _oop_cl->set_nmethod(nm);
2899 nm->oops_do(_oop_cl);
2900 }
2901 }
2902 };
2903
2904 class YoungRefCounterClosure : public OopClosure {
2905 G1CollectedHeap* _g1h;
2906 int _count;
2907 public:
2908 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2909 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2910 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2911
2912 int count() { return _count; }
2913 void reset_count() { _count = 0; };
2914 };
2915
2916 class VerifyKlassClosure: public KlassClosure {
2917 YoungRefCounterClosure _young_ref_counter_closure;
2918 OopClosure *_oop_closure;
2919 public:
2920 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2921 void do_klass(Klass* k) {
2922 k->oops_do(_oop_closure);
2923
2924 _young_ref_counter_closure.reset_count();
2925 k->oops_do(&_young_ref_counter_closure);
2926 if (_young_ref_counter_closure.count() > 0) {
2927 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2928 }
2929 }
2930 };
2931
2932 class VerifyLivenessOopClosure: public OopClosure {
2933 G1CollectedHeap* _g1h;
2934 VerifyOption _vo;
2935 public:
2936 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2937 _g1h(g1h), _vo(vo)
2938 { }
2939 void do_oop(narrowOop *p) { do_oop_work(p); }
2940 void do_oop( oop *p) { do_oop_work(p); }
2941
2942 template <class T> void do_oop_work(T *p) {
2943 oop obj = oopDesc::load_decode_heap_oop(p);
2944 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2945 "Dead object referenced by a not dead object");
2946 }
2947 };
2948
2949 class VerifyObjsInRegionClosure: public ObjectClosure {
2950 private:
2951 G1CollectedHeap* _g1h;
2952 size_t _live_bytes;
2953 HeapRegion *_hr;
2954 VerifyOption _vo;
2955 public:
2956 // _vo == UsePrevMarking -> use "prev" marking information,
2957 // _vo == UseNextMarking -> use "next" marking information,
2958 // _vo == UseMarkWord -> use mark word from object header.
2959 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2960 : _live_bytes(0), _hr(hr), _vo(vo) {
2961 _g1h = G1CollectedHeap::heap();
2962 }
2963 void do_object(oop o) {
2964 VerifyLivenessOopClosure isLive(_g1h, _vo);
2965 assert(o != NULL, "Huh?");
2966 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2967 // If the object is alive according to the mark word,
2968 // then verify that the marking information agrees.
2969 // Note we can't verify the contra-positive of the
2970 // above: if the object is dead (according to the mark
2971 // word), it may not be marked, or may have been marked
2972 // but has since became dead, or may have been allocated
2973 // since the last marking.
2974 if (_vo == VerifyOption_G1UseMarkWord) {
2975 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2976 }
2977
2978 o->oop_iterate_no_header(&isLive);
2979 if (!_hr->obj_allocated_since_prev_marking(o)) {
2980 size_t obj_size = o->size(); // Make sure we don't overflow
2981 _live_bytes += (obj_size * HeapWordSize);
2982 }
2983 }
2984 }
2985 size_t live_bytes() { return _live_bytes; }
2986 };
2987
2988 class VerifyArchiveOopClosure: public OopClosure {
2989 public:
2990 VerifyArchiveOopClosure(HeapRegion *hr) { }
2991 void do_oop(narrowOop *p) { do_oop_work(p); }
2992 void do_oop( oop *p) { do_oop_work(p); }
2993
2994 template <class T> void do_oop_work(T *p) {
2995 oop obj = oopDesc::load_decode_heap_oop(p);
2996 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2997 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2998 p2i(p), p2i(obj));
2999 }
3000 };
3001
3002 class VerifyArchiveRegionClosure: public ObjectClosure {
3003 public:
3004 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3005 // Verify that all object pointers are to archive regions.
3006 void do_object(oop o) {
3007 VerifyArchiveOopClosure checkOop(NULL);
3008 assert(o != NULL, "Should not be here for NULL oops");
3009 o->oop_iterate_no_header(&checkOop);
3010 }
3011 };
3012
3013 class VerifyRegionClosure: public HeapRegionClosure {
3014 private:
3015 bool _par;
3016 VerifyOption _vo;
3017 bool _failures;
3018 public:
3019 // _vo == UsePrevMarking -> use "prev" marking information,
3020 // _vo == UseNextMarking -> use "next" marking information,
3021 // _vo == UseMarkWord -> use mark word from object header.
3022 VerifyRegionClosure(bool par, VerifyOption vo)
3023 : _par(par),
3024 _vo(vo),
3025 _failures(false) {}
3026
3027 bool failures() {
3028 return _failures;
3029 }
3030
3031 bool doHeapRegion(HeapRegion* r) {
3032 // For archive regions, verify there are no heap pointers to
3033 // non-pinned regions. For all others, verify liveness info.
3034 if (r->is_archive()) {
3035 VerifyArchiveRegionClosure verify_oop_pointers(r);
3036 r->object_iterate(&verify_oop_pointers);
3037 return true;
3038 }
3039 if (!r->is_continues_humongous()) {
3040 bool failures = false;
3041 r->verify(_vo, &failures);
3042 if (failures) {
3043 _failures = true;
3044 } else if (!r->is_starts_humongous()) {
3045 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3046 r->object_iterate(¬_dead_yet_cl);
3047 if (_vo != VerifyOption_G1UseNextMarking) {
3048 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3049 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3050 "max_live_bytes " SIZE_FORMAT " "
3051 "< calculated " SIZE_FORMAT,
3052 p2i(r->bottom()), p2i(r->end()),
3053 r->max_live_bytes(),
3054 not_dead_yet_cl.live_bytes());
3055 _failures = true;
3056 }
3057 } else {
3058 // When vo == UseNextMarking we cannot currently do a sanity
3059 // check on the live bytes as the calculation has not been
3060 // finalized yet.
3061 }
3062 }
3063 }
3064 return false; // stop the region iteration if we hit a failure
3065 }
3066 };
3067
3068 // This is the task used for parallel verification of the heap regions
3069
3070 class G1ParVerifyTask: public AbstractGangTask {
3071 private:
3072 G1CollectedHeap* _g1h;
3073 VerifyOption _vo;
3074 bool _failures;
3075 HeapRegionClaimer _hrclaimer;
3076
3077 public:
3078 // _vo == UsePrevMarking -> use "prev" marking information,
3079 // _vo == UseNextMarking -> use "next" marking information,
3080 // _vo == UseMarkWord -> use mark word from object header.
3081 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3082 AbstractGangTask("Parallel verify task"),
3083 _g1h(g1h),
3084 _vo(vo),
3085 _failures(false),
3086 _hrclaimer(g1h->workers()->active_workers()) {}
3087
3088 bool failures() {
3089 return _failures;
3090 }
3091
3092 void work(uint worker_id) {
3093 HandleMark hm;
3094 VerifyRegionClosure blk(true, _vo);
3095 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3096 if (blk.failures()) {
3097 _failures = true;
3098 }
3099 }
3100 };
3101
3102 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3103 if (SafepointSynchronize::is_at_safepoint()) {
3104 assert(Thread::current()->is_VM_thread(),
3105 "Expected to be executed serially by the VM thread at this point");
3106
3107 if (!silent) { gclog_or_tty->print("Roots "); }
3108 VerifyRootsClosure rootsCl(vo);
3109 VerifyKlassClosure klassCl(this, &rootsCl);
3110 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3111
3112 // We apply the relevant closures to all the oops in the
3113 // system dictionary, class loader data graph, the string table
3114 // and the nmethods in the code cache.
3115 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3116 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3117
3118 {
3119 G1RootProcessor root_processor(this, 1);
3120 root_processor.process_all_roots(&rootsCl,
3121 &cldCl,
3122 &blobsCl);
3123 }
3124
3125 bool failures = rootsCl.failures() || codeRootsCl.failures();
3126
3127 if (vo != VerifyOption_G1UseMarkWord) {
3128 // If we're verifying during a full GC then the region sets
3129 // will have been torn down at the start of the GC. Therefore
3130 // verifying the region sets will fail. So we only verify
3131 // the region sets when not in a full GC.
3132 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3133 verify_region_sets();
3134 }
3135
3136 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3137 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3138
3139 G1ParVerifyTask task(this, vo);
3140 workers()->run_task(&task);
3141 if (task.failures()) {
3142 failures = true;
3143 }
3144
3145 } else {
3146 VerifyRegionClosure blk(false, vo);
3147 heap_region_iterate(&blk);
3148 if (blk.failures()) {
3149 failures = true;
3150 }
3151 }
3152
3153 if (G1StringDedup::is_enabled()) {
3154 if (!silent) gclog_or_tty->print("StrDedup ");
3155 G1StringDedup::verify();
3156 }
3157
3158 if (failures) {
3159 gclog_or_tty->print_cr("Heap:");
3160 // It helps to have the per-region information in the output to
3161 // help us track down what went wrong. This is why we call
3162 // print_extended_on() instead of print_on().
3163 print_extended_on(gclog_or_tty);
3164 gclog_or_tty->cr();
3165 gclog_or_tty->flush();
3166 }
3167 guarantee(!failures, "there should not have been any failures");
3168 } else {
3169 if (!silent) {
3170 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3171 if (G1StringDedup::is_enabled()) {
3172 gclog_or_tty->print(", StrDedup");
3173 }
3174 gclog_or_tty->print(") ");
3175 }
3176 }
3177 }
3178
3179 void G1CollectedHeap::verify(bool silent) {
3180 verify(silent, VerifyOption_G1UsePrevMarking);
3181 }
3182
3183 double G1CollectedHeap::verify(bool guard, const char* msg) {
3184 double verify_time_ms = 0.0;
3185
3186 if (guard && total_collections() >= VerifyGCStartAt) {
3187 double verify_start = os::elapsedTime();
3188 HandleMark hm; // Discard invalid handles created during verification
3189 prepare_for_verify();
3190 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3191 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3192 }
3193
3194 return verify_time_ms;
3195 }
3196
3197 void G1CollectedHeap::verify_before_gc() {
3198 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3199 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3200 }
3201
3202 void G1CollectedHeap::verify_after_gc() {
3203 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3204 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3205 }
3206
3207 class PrintRegionClosure: public HeapRegionClosure {
3208 outputStream* _st;
3209 public:
3210 PrintRegionClosure(outputStream* st) : _st(st) {}
3211 bool doHeapRegion(HeapRegion* r) {
3212 r->print_on(_st);
3213 return false;
3214 }
3215 };
3216
3217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3218 const HeapRegion* hr,
3219 const VerifyOption vo) const {
3220 switch (vo) {
3221 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3222 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3223 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3224 default: ShouldNotReachHere();
3225 }
3226 return false; // keep some compilers happy
3227 }
3228
3229 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3230 const VerifyOption vo) const {
3231 switch (vo) {
3232 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3233 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3234 case VerifyOption_G1UseMarkWord: {
3235 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3236 return !obj->is_gc_marked() && !hr->is_archive();
3237 }
3238 default: ShouldNotReachHere();
3239 }
3240 return false; // keep some compilers happy
3241 }
3242
3243 void G1CollectedHeap::print_on(outputStream* st) const {
3244 st->print(" %-20s", "garbage-first heap");
3245 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3246 capacity()/K, used_unlocked()/K);
3247 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3248 p2i(_hrm.reserved().start()),
3249 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3250 p2i(_hrm.reserved().end()));
3251 st->cr();
3252 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3253 uint young_regions = _young_list->length();
3254 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3255 (size_t) young_regions * HeapRegion::GrainBytes / K);
3256 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3257 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3258 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3259 st->cr();
3260 MetaspaceAux::print_on(st);
3261 }
3262
3263 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3264 print_on(st);
3265
3266 // Print the per-region information.
3267 st->cr();
3268 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3269 "HS=humongous(starts), HC=humongous(continues), "
3270 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3271 "PTAMS=previous top-at-mark-start, "
3272 "NTAMS=next top-at-mark-start)");
3273 PrintRegionClosure blk(st);
3274 heap_region_iterate(&blk);
3275 }
3276
3277 void G1CollectedHeap::print_on_error(outputStream* st) const {
3278 this->CollectedHeap::print_on_error(st);
3279
3280 if (_cm != NULL) {
3281 st->cr();
3282 _cm->print_on_error(st);
3283 }
3284 }
3285
3286 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3287 workers()->print_worker_threads_on(st);
3288 _cmThread->print_on(st);
3289 st->cr();
3290 _cm->print_worker_threads_on(st);
3291 _cg1r->print_worker_threads_on(st);
3292 if (G1StringDedup::is_enabled()) {
3293 G1StringDedup::print_worker_threads_on(st);
3294 }
3295 }
3296
3297 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3298 workers()->threads_do(tc);
3299 tc->do_thread(_cmThread);
3300 _cg1r->threads_do(tc);
3301 if (G1StringDedup::is_enabled()) {
3302 G1StringDedup::threads_do(tc);
3303 }
3304 }
3305
3306 void G1CollectedHeap::print_tracing_info() const {
3307 // We'll overload this to mean "trace GC pause statistics."
3308 if (TraceYoungGenTime || TraceOldGenTime) {
3309 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3310 // to that.
3311 g1_policy()->print_tracing_info();
3312 }
3313 if (G1SummarizeRSetStats) {
3314 g1_rem_set()->print_summary_info();
3315 }
3316 if (G1SummarizeConcMark) {
3317 concurrent_mark()->print_summary_info();
3318 }
3319 g1_policy()->print_yg_surv_rate_info();
3320 }
3321
3322 #ifndef PRODUCT
3323 // Helpful for debugging RSet issues.
3324
3325 class PrintRSetsClosure : public HeapRegionClosure {
3326 private:
3327 const char* _msg;
3328 size_t _occupied_sum;
3329
3330 public:
3331 bool doHeapRegion(HeapRegion* r) {
3332 HeapRegionRemSet* hrrs = r->rem_set();
3333 size_t occupied = hrrs->occupied();
3334 _occupied_sum += occupied;
3335
3336 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3337 HR_FORMAT_PARAMS(r));
3338 if (occupied == 0) {
3339 gclog_or_tty->print_cr(" RSet is empty");
3340 } else {
3341 hrrs->print();
3342 }
3343 gclog_or_tty->print_cr("----------");
3344 return false;
3345 }
3346
3347 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3348 gclog_or_tty->cr();
3349 gclog_or_tty->print_cr("========================================");
3350 gclog_or_tty->print_cr("%s", msg);
3351 gclog_or_tty->cr();
3352 }
3353
3354 ~PrintRSetsClosure() {
3355 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3356 gclog_or_tty->print_cr("========================================");
3357 gclog_or_tty->cr();
3358 }
3359 };
3360
3361 void G1CollectedHeap::print_cset_rsets() {
3362 PrintRSetsClosure cl("Printing CSet RSets");
3363 collection_set_iterate(&cl);
3364 }
3365
3366 void G1CollectedHeap::print_all_rsets() {
3367 PrintRSetsClosure cl("Printing All RSets");;
3368 heap_region_iterate(&cl);
3369 }
3370 #endif // PRODUCT
3371
3372 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3373 YoungList* young_list = heap()->young_list();
3374
3375 size_t eden_used_bytes = young_list->eden_used_bytes();
3376 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3377
3378 size_t eden_capacity_bytes =
3379 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3380
3381 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3382 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3383 }
3384
3385 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3386 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3387 stats->unused(), stats->used(), stats->region_end_waste(),
3388 stats->regions_filled(), stats->direct_allocated(),
3389 stats->failure_used(), stats->failure_waste());
3390 }
3391
3392 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3393 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3394 gc_tracer->report_gc_heap_summary(when, heap_summary);
3395
3396 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3397 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3398 }
3399
3400
3401 G1CollectedHeap* G1CollectedHeap::heap() {
3402 CollectedHeap* heap = Universe::heap();
3403 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3404 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3405 return (G1CollectedHeap*)heap;
3406 }
3407
3408 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3409 // always_do_update_barrier = false;
3410 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3411 // Fill TLAB's and such
3412 accumulate_statistics_all_tlabs();
3413 ensure_parsability(true);
3414
3415 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3416 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3417 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3418 }
3419 }
3420
3421 void G1CollectedHeap::gc_epilogue(bool full) {
3422
3423 if (G1SummarizeRSetStats &&
3424 (G1SummarizeRSetStatsPeriod > 0) &&
3425 // we are at the end of the GC. Total collections has already been increased.
3426 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3427 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3428 }
3429
3430 // FIXME: what is this about?
3431 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3432 // is set.
3433 #if defined(COMPILER2) || INCLUDE_JVMCI
3434 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3435 #endif
3436 // always_do_update_barrier = true;
3437
3438 resize_all_tlabs();
3439 allocation_context_stats().update(full);
3440
3441 // We have just completed a GC. Update the soft reference
3442 // policy with the new heap occupancy
3443 Universe::update_heap_info_at_gc();
3444 }
3445
3446 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3447 uint gc_count_before,
3448 bool* succeeded,
3449 GCCause::Cause gc_cause) {
3450 assert_heap_not_locked_and_not_at_safepoint();
3451 g1_policy()->record_stop_world_start();
3452 VM_G1IncCollectionPause op(gc_count_before,
3453 word_size,
3454 false, /* should_initiate_conc_mark */
3455 g1_policy()->max_pause_time_ms(),
3456 gc_cause);
3457
3458 op.set_allocation_context(AllocationContext::current());
3459 VMThread::execute(&op);
3460
3461 HeapWord* result = op.result();
3462 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3463 assert(result == NULL || ret_succeeded,
3464 "the result should be NULL if the VM did not succeed");
3465 *succeeded = ret_succeeded;
3466
3467 assert_heap_not_locked();
3468 return result;
3469 }
3470
3471 void
3472 G1CollectedHeap::doConcurrentMark() {
3473 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3474 if (!_cmThread->in_progress()) {
3475 _cmThread->set_started();
3476 CGC_lock->notify();
3477 }
3478 }
3479
3480 size_t G1CollectedHeap::pending_card_num() {
3481 size_t extra_cards = 0;
3482 JavaThread *curr = Threads::first();
3483 while (curr != NULL) {
3484 DirtyCardQueue& dcq = curr->dirty_card_queue();
3485 extra_cards += dcq.size();
3486 curr = curr->next();
3487 }
3488 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3489 size_t buffer_size = dcqs.buffer_size();
3490 size_t buffer_num = dcqs.completed_buffers_num();
3491
3492 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3493 // in bytes - not the number of 'entries'. We need to convert
3494 // into a number of cards.
3495 return (buffer_size * buffer_num + extra_cards) / oopSize;
3496 }
3497
3498 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3499 private:
3500 size_t _total_humongous;
3501 size_t _candidate_humongous;
3502
3503 DirtyCardQueue _dcq;
3504
3505 // We don't nominate objects with many remembered set entries, on
3506 // the assumption that such objects are likely still live.
3507 bool is_remset_small(HeapRegion* region) const {
3508 HeapRegionRemSet* const rset = region->rem_set();
3509 return G1EagerReclaimHumongousObjectsWithStaleRefs
3510 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3511 : rset->is_empty();
3512 }
3513
3514 bool is_typeArray_region(HeapRegion* region) const {
3515 return oop(region->bottom())->is_typeArray();
3516 }
3517
3518 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3519 assert(region->is_starts_humongous(), "Must start a humongous object");
3520
3521 // Candidate selection must satisfy the following constraints
3522 // while concurrent marking is in progress:
3523 //
3524 // * In order to maintain SATB invariants, an object must not be
3525 // reclaimed if it was allocated before the start of marking and
3526 // has not had its references scanned. Such an object must have
3527 // its references (including type metadata) scanned to ensure no
3528 // live objects are missed by the marking process. Objects
3529 // allocated after the start of concurrent marking don't need to
3530 // be scanned.
3531 //
3532 // * An object must not be reclaimed if it is on the concurrent
3533 // mark stack. Objects allocated after the start of concurrent
3534 // marking are never pushed on the mark stack.
3535 //
3536 // Nominating only objects allocated after the start of concurrent
3537 // marking is sufficient to meet both constraints. This may miss
3538 // some objects that satisfy the constraints, but the marking data
3539 // structures don't support efficiently performing the needed
3540 // additional tests or scrubbing of the mark stack.
3541 //
3542 // However, we presently only nominate is_typeArray() objects.
3543 // A humongous object containing references induces remembered
3544 // set entries on other regions. In order to reclaim such an
3545 // object, those remembered sets would need to be cleaned up.
3546 //
3547 // We also treat is_typeArray() objects specially, allowing them
3548 // to be reclaimed even if allocated before the start of
3549 // concurrent mark. For this we rely on mark stack insertion to
3550 // exclude is_typeArray() objects, preventing reclaiming an object
3551 // that is in the mark stack. We also rely on the metadata for
3552 // such objects to be built-in and so ensured to be kept live.
3553 // Frequent allocation and drop of large binary blobs is an
3554 // important use case for eager reclaim, and this special handling
3555 // may reduce needed headroom.
3556
3557 return is_typeArray_region(region) && is_remset_small(region);
3558 }
3559
3560 public:
3561 RegisterHumongousWithInCSetFastTestClosure()
3562 : _total_humongous(0),
3563 _candidate_humongous(0),
3564 _dcq(&JavaThread::dirty_card_queue_set()) {
3565 }
3566
3567 virtual bool doHeapRegion(HeapRegion* r) {
3568 if (!r->is_starts_humongous()) {
3569 return false;
3570 }
3571 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3572
3573 bool is_candidate = humongous_region_is_candidate(g1h, r);
3574 uint rindex = r->hrm_index();
3575 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3576 if (is_candidate) {
3577 _candidate_humongous++;
3578 g1h->register_humongous_region_with_cset(rindex);
3579 // Is_candidate already filters out humongous object with large remembered sets.
3580 // If we have a humongous object with a few remembered sets, we simply flush these
3581 // remembered set entries into the DCQS. That will result in automatic
3582 // re-evaluation of their remembered set entries during the following evacuation
3583 // phase.
3584 if (!r->rem_set()->is_empty()) {
3585 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3586 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3587 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3588 HeapRegionRemSetIterator hrrs(r->rem_set());
3589 size_t card_index;
3590 while (hrrs.has_next(card_index)) {
3591 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3592 // The remembered set might contain references to already freed
3593 // regions. Filter out such entries to avoid failing card table
3594 // verification.
3595 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3596 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3597 *card_ptr = CardTableModRefBS::dirty_card_val();
3598 _dcq.enqueue(card_ptr);
3599 }
3600 }
3601 }
3602 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3603 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3604 hrrs.n_yielded(), r->rem_set()->occupied());
3605 r->rem_set()->clear_locked();
3606 }
3607 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3608 }
3609 _total_humongous++;
3610
3611 return false;
3612 }
3613
3614 size_t total_humongous() const { return _total_humongous; }
3615 size_t candidate_humongous() const { return _candidate_humongous; }
3616
3617 void flush_rem_set_entries() { _dcq.flush(); }
3618 };
3619
3620 void G1CollectedHeap::register_humongous_regions_with_cset() {
3621 if (!G1EagerReclaimHumongousObjects) {
3622 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3623 return;
3624 }
3625 double time = os::elapsed_counter();
3626
3627 // Collect reclaim candidate information and register candidates with cset.
3628 RegisterHumongousWithInCSetFastTestClosure cl;
3629 heap_region_iterate(&cl);
3630
3631 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3632 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3633 cl.total_humongous(),
3634 cl.candidate_humongous());
3635 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3636
3637 // Finally flush all remembered set entries to re-check into the global DCQS.
3638 cl.flush_rem_set_entries();
3639 }
3640
3641 class VerifyRegionRSetClosure : public HeapRegionClosure {
3642 public:
3643 bool doHeapRegion(HeapRegion* hr) {
3644 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3645 bool dummy = false;
3646 hr->verifyRSet(VerifyOption_G1UsePrevMarking, &dummy);
3647 }
3648 return false;
3649 }
3650 };
3651
3652 #ifdef ASSERT
3653 class VerifyCSetClosure: public HeapRegionClosure {
3654 public:
3655 bool doHeapRegion(HeapRegion* hr) {
3656 // Here we check that the CSet region's RSet is ready for parallel
3657 // iteration. The fields that we'll verify are only manipulated
3658 // when the region is part of a CSet and is collected. Afterwards,
3659 // we reset these fields when we clear the region's RSet (when the
3660 // region is freed) so they are ready when the region is
3661 // re-allocated. The only exception to this is if there's an
3662 // evacuation failure and instead of freeing the region we leave
3663 // it in the heap. In that case, we reset these fields during
3664 // evacuation failure handling.
3665 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3666
3667 // Here's a good place to add any other checks we'd like to
3668 // perform on CSet regions.
3669 return false;
3670 }
3671 };
3672 #endif // ASSERT
3673
3674 uint G1CollectedHeap::num_task_queues() const {
3675 return _task_queues->size();
3676 }
3677
3678 #if TASKQUEUE_STATS
3679 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3680 st->print_raw_cr("GC Task Stats");
3681 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3682 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3683 }
3684
3685 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3686 print_taskqueue_stats_hdr(st);
3687
3688 TaskQueueStats totals;
3689 const uint n = num_task_queues();
3690 for (uint i = 0; i < n; ++i) {
3691 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3692 totals += task_queue(i)->stats;
3693 }
3694 st->print_raw("tot "); totals.print(st); st->cr();
3695
3696 DEBUG_ONLY(totals.verify());
3697 }
3698
3699 void G1CollectedHeap::reset_taskqueue_stats() {
3700 const uint n = num_task_queues();
3701 for (uint i = 0; i < n; ++i) {
3702 task_queue(i)->stats.reset();
3703 }
3704 }
3705 #endif // TASKQUEUE_STATS
3706
3707 void G1CollectedHeap::log_gc_header() {
3708 if (!G1Log::fine()) {
3709 return;
3710 }
3711
3712 gclog_or_tty->gclog_stamp();
3713
3714 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3715 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3716 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3717
3718 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3719 }
3720
3721 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3722 if (!G1Log::fine()) {
3723 return;
3724 }
3725
3726 if (G1Log::finer()) {
3727 if (evacuation_failed()) {
3728 gclog_or_tty->print(" (to-space exhausted)");
3729 }
3730 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3731 g1_policy()->print_phases(pause_time_sec);
3732 g1_policy()->print_detailed_heap_transition();
3733 } else {
3734 if (evacuation_failed()) {
3735 gclog_or_tty->print("--");
3736 }
3737 g1_policy()->print_heap_transition();
3738 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3739 }
3740 gclog_or_tty->flush();
3741 }
3742
3743 void G1CollectedHeap::wait_for_root_region_scanning() {
3744 double scan_wait_start = os::elapsedTime();
3745 // We have to wait until the CM threads finish scanning the
3746 // root regions as it's the only way to ensure that all the
3747 // objects on them have been correctly scanned before we start
3748 // moving them during the GC.
3749 bool waited = _cm->root_regions()->wait_until_scan_finished();
3750 double wait_time_ms = 0.0;
3751 if (waited) {
3752 double scan_wait_end = os::elapsedTime();
3753 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3754 }
3755 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3756 }
3757
3758 bool
3759 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3760 assert_at_safepoint(true /* should_be_vm_thread */);
3761 guarantee(!is_gc_active(), "collection is not reentrant");
3762
3763 if (GC_locker::check_active_before_gc()) {
3764 return false;
3765 }
3766
3767 _gc_timer_stw->register_gc_start();
3768
3769 GCIdMark gc_id_mark;
3770 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3771
3772 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3773 ResourceMark rm;
3774
3775 wait_for_root_region_scanning();
3776
3777 G1Log::update_level();
3778 print_heap_before_gc();
3779 trace_heap_before_gc(_gc_tracer_stw);
3780
3781 verify_region_sets_optional();
3782 verify_dirty_young_regions();
3783
3784 // This call will decide whether this pause is an initial-mark
3785 // pause. If it is, during_initial_mark_pause() will return true
3786 // for the duration of this pause.
3787 g1_policy()->decide_on_conc_mark_initiation();
3788
3789 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3790 assert(!collector_state()->during_initial_mark_pause() ||
3791 collector_state()->gcs_are_young(), "sanity");
3792
3793 // We also do not allow mixed GCs during marking.
3794 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3795
3796 // Record whether this pause is an initial mark. When the current
3797 // thread has completed its logging output and it's safe to signal
3798 // the CM thread, the flag's value in the policy has been reset.
3799 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3800
3801 // Inner scope for scope based logging, timers, and stats collection
3802 {
3803 EvacuationInfo evacuation_info;
3804
3805 if (collector_state()->during_initial_mark_pause()) {
3806 // We are about to start a marking cycle, so we increment the
3807 // full collection counter.
3808 increment_old_marking_cycles_started();
3809 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3810 }
3811
3812 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3813
3814 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3815
3816 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3817 workers()->active_workers(),
3818 Threads::number_of_non_daemon_threads());
3819 workers()->set_active_workers(active_workers);
3820
3821 double pause_start_sec = os::elapsedTime();
3822 g1_policy()->note_gc_start(active_workers);
3823 log_gc_header();
3824
3825 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3826 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3827
3828 // If the secondary_free_list is not empty, append it to the
3829 // free_list. No need to wait for the cleanup operation to finish;
3830 // the region allocation code will check the secondary_free_list
3831 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3832 // set, skip this step so that the region allocation code has to
3833 // get entries from the secondary_free_list.
3834 if (!G1StressConcRegionFreeing) {
3835 append_secondary_free_list_if_not_empty_with_lock();
3836 }
3837
3838 assert(check_young_list_well_formed(), "young list should be well formed");
3839
3840 // Don't dynamically change the number of GC threads this early. A value of
3841 // 0 is used to indicate serial work. When parallel work is done,
3842 // it will be set.
3843
3844 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3845 IsGCActiveMark x;
3846
3847 gc_prologue(false);
3848 increment_total_collections(false /* full gc */);
3849 increment_gc_time_stamp();
3850
3851 verify_before_gc();
3852
3853 check_bitmaps("GC Start");
3854
3855 #if defined(COMPILER2) || INCLUDE_JVMCI
3856 DerivedPointerTable::clear();
3857 #endif
3858
3859 // Please see comment in g1CollectedHeap.hpp and
3860 // G1CollectedHeap::ref_processing_init() to see how
3861 // reference processing currently works in G1.
3862
3863 // Enable discovery in the STW reference processor
3864 if (g1_policy()->should_process_references()) {
3865 ref_processor_stw()->enable_discovery();
3866 } else {
3867 ref_processor_stw()->disable_discovery();
3868 }
3869
3870 {
3871 // We want to temporarily turn off discovery by the
3872 // CM ref processor, if necessary, and turn it back on
3873 // on again later if we do. Using a scoped
3874 // NoRefDiscovery object will do this.
3875 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3876
3877 // Forget the current alloc region (we might even choose it to be part
3878 // of the collection set!).
3879 _allocator->release_mutator_alloc_region();
3880
3881 // We should call this after we retire the mutator alloc
3882 // region(s) so that all the ALLOC / RETIRE events are generated
3883 // before the start GC event.
3884 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3885
3886 // This timing is only used by the ergonomics to handle our pause target.
3887 // It is unclear why this should not include the full pause. We will
3888 // investigate this in CR 7178365.
3889 //
3890 // Preserving the old comment here if that helps the investigation:
3891 //
3892 // The elapsed time induced by the start time below deliberately elides
3893 // the possible verification above.
3894 double sample_start_time_sec = os::elapsedTime();
3895
3896 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3897
3898 if (collector_state()->during_initial_mark_pause()) {
3899 concurrent_mark()->checkpointRootsInitialPre();
3900 }
3901
3902 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3903 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3904
3905 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3906
3907 // Make sure the remembered sets are up to date. This needs to be
3908 // done before register_humongous_regions_with_cset(), because the
3909 // remembered sets are used there to choose eager reclaim candidates.
3910 // If the remembered sets are not up to date we might miss some
3911 // entries that need to be handled.
3912 g1_rem_set()->cleanupHRRS();
3913
3914 register_humongous_regions_with_cset();
3915
3916 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3917
3918 _cm->note_start_of_gc();
3919 // We call this after finalize_cset() to
3920 // ensure that the CSet has been finalized.
3921 _cm->verify_no_cset_oops();
3922
3923 if (_hr_printer.is_active()) {
3924 HeapRegion* hr = g1_policy()->collection_set();
3925 while (hr != NULL) {
3926 _hr_printer.cset(hr);
3927 hr = hr->next_in_collection_set();
3928 }
3929 }
3930
3931 #ifdef ASSERT
3932 VerifyCSetClosure cl;
3933 collection_set_iterate(&cl);
3934 #endif // ASSERT
3935
3936 // Initialize the GC alloc regions.
3937 _allocator->init_gc_alloc_regions(evacuation_info);
3938
3939 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3940 pre_evacuate_collection_set();
3941
3942 // Actually do the work...
3943 evacuate_collection_set(evacuation_info, &per_thread_states);
3944
3945 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3946
3947 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3948 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3949
3950 eagerly_reclaim_humongous_regions();
3951
3952 g1_policy()->clear_collection_set();
3953
3954 // Start a new incremental collection set for the next pause.
3955 g1_policy()->start_incremental_cset_building();
3956
3957 clear_cset_fast_test();
3958
3959 _young_list->reset_sampled_info();
3960
3961 // Don't check the whole heap at this point as the
3962 // GC alloc regions from this pause have been tagged
3963 // as survivors and moved on to the survivor list.
3964 // Survivor regions will fail the !is_young() check.
3965 assert(check_young_list_empty(false /* check_heap */),
3966 "young list should be empty");
3967
3968 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3969 _young_list->first_survivor_region(),
3970 _young_list->last_survivor_region());
3971
3972 _young_list->reset_auxilary_lists();
3973
3974 if (evacuation_failed()) {
3975 set_used(recalculate_used());
3976 if (_archive_allocator != NULL) {
3977 _archive_allocator->clear_used();
3978 }
3979 for (uint i = 0; i < ParallelGCThreads; i++) {
3980 if (_evacuation_failed_info_array[i].has_failed()) {
3981 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3982 }
3983 }
3984 } else {
3985 // The "used" of the the collection set have already been subtracted
3986 // when they were freed. Add in the bytes evacuated.
3987 increase_used(g1_policy()->bytes_copied_during_gc());
3988 }
3989
3990 if (collector_state()->during_initial_mark_pause()) {
3991 // We have to do this before we notify the CM threads that
3992 // they can start working to make sure that all the
3993 // appropriate initialization is done on the CM object.
3994 concurrent_mark()->checkpointRootsInitialPost();
3995 collector_state()->set_mark_in_progress(true);
3996 // Note that we don't actually trigger the CM thread at
3997 // this point. We do that later when we're sure that
3998 // the current thread has completed its logging output.
3999 }
4000
4001 allocate_dummy_regions();
4002
4003 _allocator->init_mutator_alloc_region();
4004
4005 {
4006 size_t expand_bytes = g1_policy()->expansion_amount();
4007 if (expand_bytes > 0) {
4008 size_t bytes_before = capacity();
4009 // No need for an ergo verbose message here,
4010 // expansion_amount() does this when it returns a value > 0.
4011 double expand_ms;
4012 if (!expand(expand_bytes, &expand_ms)) {
4013 // We failed to expand the heap. Cannot do anything about it.
4014 }
4015 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4016 }
4017 }
4018
4019 // We redo the verification but now wrt to the new CSet which
4020 // has just got initialized after the previous CSet was freed.
4021 _cm->verify_no_cset_oops();
4022 _cm->note_end_of_gc();
4023
4024 // This timing is only used by the ergonomics to handle our pause target.
4025 // It is unclear why this should not include the full pause. We will
4026 // investigate this in CR 7178365.
4027 double sample_end_time_sec = os::elapsedTime();
4028 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4029 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4030 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4031
4032 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4033 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4034
4035 MemoryService::track_memory_usage();
4036
4037 // In prepare_for_verify() below we'll need to scan the deferred
4038 // update buffers to bring the RSets up-to-date if
4039 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4040 // the update buffers we'll probably need to scan cards on the
4041 // regions we just allocated to (i.e., the GC alloc
4042 // regions). However, during the last GC we called
4043 // set_saved_mark() on all the GC alloc regions, so card
4044 // scanning might skip the [saved_mark_word()...top()] area of
4045 // those regions (i.e., the area we allocated objects into
4046 // during the last GC). But it shouldn't. Given that
4047 // saved_mark_word() is conditional on whether the GC time stamp
4048 // on the region is current or not, by incrementing the GC time
4049 // stamp here we invalidate all the GC time stamps on all the
4050 // regions and saved_mark_word() will simply return top() for
4051 // all the regions. This is a nicer way of ensuring this rather
4052 // than iterating over the regions and fixing them. In fact, the
4053 // GC time stamp increment here also ensures that
4054 // saved_mark_word() will return top() between pauses, i.e.,
4055 // during concurrent refinement. So we don't need the
4056 // is_gc_active() check to decided which top to use when
4057 // scanning cards (see CR 7039627).
4058 increment_gc_time_stamp();
4059
4060 if (G1VerifyRSetsAfterEvacuationPause) {
4061 gclog_or_tty->print("[Verifying RSets]");
4062 VerifyRegionRSetClosure v_cl;
4063 heap_region_iterate(&v_cl);
4064 }
4065
4066 verify_after_gc();
4067 check_bitmaps("GC End");
4068
4069 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4070 ref_processor_stw()->verify_no_references_recorded();
4071
4072 // CM reference discovery will be re-enabled if necessary.
4073 }
4074
4075 // We should do this after we potentially expand the heap so
4076 // that all the COMMIT events are generated before the end GC
4077 // event, and after we retire the GC alloc regions so that all
4078 // RETIRE events are generated before the end GC event.
4079 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4080
4081 #ifdef TRACESPINNING
4082 ParallelTaskTerminator::print_termination_counts();
4083 #endif
4084
4085 gc_epilogue(false);
4086 }
4087
4088 // Print the remainder of the GC log output.
4089 log_gc_footer(os::elapsedTime() - pause_start_sec);
4090
4091 // It is not yet to safe to tell the concurrent mark to
4092 // start as we have some optional output below. We don't want the
4093 // output from the concurrent mark thread interfering with this
4094 // logging output either.
4095
4096 _hrm.verify_optional();
4097 verify_region_sets_optional();
4098
4099 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4100 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4101
4102 print_heap_after_gc();
4103 trace_heap_after_gc(_gc_tracer_stw);
4104
4105 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4106 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4107 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4108 // before any GC notifications are raised.
4109 g1mm()->update_sizes();
4110
4111 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4112 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4113 _gc_timer_stw->register_gc_end();
4114 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4115 }
4116 // It should now be safe to tell the concurrent mark thread to start
4117 // without its logging output interfering with the logging output
4118 // that came from the pause.
4119
4120 if (should_start_conc_mark) {
4121 // CAUTION: after the doConcurrentMark() call below,
4122 // the concurrent marking thread(s) could be running
4123 // concurrently with us. Make sure that anything after
4124 // this point does not assume that we are the only GC thread
4125 // running. Note: of course, the actual marking work will
4126 // not start until the safepoint itself is released in
4127 // SuspendibleThreadSet::desynchronize().
4128 doConcurrentMark();
4129 }
4130
4131 return true;
4132 }
4133
4134 void G1CollectedHeap::restore_preserved_marks() {
4135 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4136 workers()->run_task(&rpm_task);
4137 }
4138
4139 void G1CollectedHeap::remove_self_forwarding_pointers() {
4140 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4141 workers()->run_task(&rsfp_task);
4142 }
4143
4144 void G1CollectedHeap::restore_after_evac_failure() {
4145 double remove_self_forwards_start = os::elapsedTime();
4146
4147 remove_self_forwarding_pointers();
4148 restore_preserved_marks();
4149
4150 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4151 }
4152
4153 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4154 if (!_evacuation_failed) {
4155 _evacuation_failed = true;
4156 }
4157
4158 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4159
4160 // We want to call the "for_promotion_failure" version only in the
4161 // case of a promotion failure.
4162 if (m->must_be_preserved_for_promotion_failure(obj)) {
4163 OopAndMarkOop elem(obj, m);
4164 _preserved_objs[worker_id].push(elem);
4165 }
4166 }
4167
4168 bool G1ParEvacuateFollowersClosure::offer_termination() {
4169 G1ParScanThreadState* const pss = par_scan_state();
4170 start_term_time();
4171 const bool res = terminator()->offer_termination();
4172 end_term_time();
4173 return res;
4174 }
4175
4176 void G1ParEvacuateFollowersClosure::do_void() {
4177 G1ParScanThreadState* const pss = par_scan_state();
4178 pss->trim_queue();
4179 do {
4180 pss->steal_and_trim_queue(queues());
4181 } while (!offer_termination());
4182 }
4183
4184 class G1ParTask : public AbstractGangTask {
4185 protected:
4186 G1CollectedHeap* _g1h;
4187 G1ParScanThreadStateSet* _pss;
4188 RefToScanQueueSet* _queues;
4189 G1RootProcessor* _root_processor;
4190 ParallelTaskTerminator _terminator;
4191 uint _n_workers;
4192
4193 public:
4194 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4195 : AbstractGangTask("G1 collection"),
4196 _g1h(g1h),
4197 _pss(per_thread_states),
4198 _queues(task_queues),
4199 _root_processor(root_processor),
4200 _terminator(n_workers, _queues),
4201 _n_workers(n_workers)
4202 {}
4203
4204 void work(uint worker_id) {
4205 if (worker_id >= _n_workers) return; // no work needed this round
4206
4207 double start_sec = os::elapsedTime();
4208 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4209
4210 {
4211 ResourceMark rm;
4212 HandleMark hm;
4213
4214 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4215
4216 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4217 pss->set_ref_processor(rp);
4218
4219 double start_strong_roots_sec = os::elapsedTime();
4220
4221 _root_processor->evacuate_roots(pss->closures(), worker_id);
4222
4223 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4224
4225 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4226 // treating the nmethods visited to act as roots for concurrent marking.
4227 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4228 // objects copied by the current evacuation.
4229 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4230 pss->closures()->weak_codeblobs(),
4231 worker_id);
4232
4233 _pss->add_cards_scanned(worker_id, cards_scanned);
4234
4235 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4236
4237 double term_sec = 0.0;
4238 size_t evac_term_attempts = 0;
4239 {
4240 double start = os::elapsedTime();
4241 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4242 evac.do_void();
4243
4244 evac_term_attempts = evac.term_attempts();
4245 term_sec = evac.term_time();
4246 double elapsed_sec = os::elapsedTime() - start;
4247 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4248 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4249 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4250 }
4251
4252 assert(pss->queue_is_empty(), "should be empty");
4253
4254 if (PrintTerminationStats) {
4255 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4256 size_t lab_waste;
4257 size_t lab_undo_waste;
4258 pss->waste(lab_waste, lab_undo_waste);
4259 _g1h->print_termination_stats(gclog_or_tty,
4260 worker_id,
4261 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4262 strong_roots_sec * 1000.0, /* strong roots time */
4263 term_sec * 1000.0, /* evac term time */
4264 evac_term_attempts, /* evac term attempts */
4265 lab_waste, /* alloc buffer waste */
4266 lab_undo_waste /* undo waste */
4267 );
4268 }
4269
4270 // Close the inner scope so that the ResourceMark and HandleMark
4271 // destructors are executed here and are included as part of the
4272 // "GC Worker Time".
4273 }
4274 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4275 }
4276 };
4277
4278 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4279 st->print_raw_cr("GC Termination Stats");
4280 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4281 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4282 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4283 }
4284
4285 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4286 uint worker_id,
4287 double elapsed_ms,
4288 double strong_roots_ms,
4289 double term_ms,
4290 size_t term_attempts,
4291 size_t alloc_buffer_waste,
4292 size_t undo_waste) const {
4293 st->print_cr("%3d %9.2f %9.2f %6.2f "
4294 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4295 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4296 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4297 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4298 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4299 alloc_buffer_waste * HeapWordSize / K,
4300 undo_waste * HeapWordSize / K);
4301 }
4302
4303 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4304 private:
4305 BoolObjectClosure* _is_alive;
4306 int _initial_string_table_size;
4307 int _initial_symbol_table_size;
4308
4309 bool _process_strings;
4310 int _strings_processed;
4311 int _strings_removed;
4312
4313 bool _process_symbols;
4314 int _symbols_processed;
4315 int _symbols_removed;
4316
4317 public:
4318 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4319 AbstractGangTask("String/Symbol Unlinking"),
4320 _is_alive(is_alive),
4321 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4322 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4323
4324 _initial_string_table_size = StringTable::the_table()->table_size();
4325 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4326 if (process_strings) {
4327 StringTable::clear_parallel_claimed_index();
4328 }
4329 if (process_symbols) {
4330 SymbolTable::clear_parallel_claimed_index();
4331 }
4332 }
4333
4334 ~G1StringSymbolTableUnlinkTask() {
4335 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4336 "claim value %d after unlink less than initial string table size %d",
4337 StringTable::parallel_claimed_index(), _initial_string_table_size);
4338 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4339 "claim value %d after unlink less than initial symbol table size %d",
4340 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4341
4342 if (G1TraceStringSymbolTableScrubbing) {
4343 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4344 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4345 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4346 strings_processed(), strings_removed(),
4347 symbols_processed(), symbols_removed());
4348 }
4349 }
4350
4351 void work(uint worker_id) {
4352 int strings_processed = 0;
4353 int strings_removed = 0;
4354 int symbols_processed = 0;
4355 int symbols_removed = 0;
4356 if (_process_strings) {
4357 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4358 Atomic::add(strings_processed, &_strings_processed);
4359 Atomic::add(strings_removed, &_strings_removed);
4360 }
4361 if (_process_symbols) {
4362 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4363 Atomic::add(symbols_processed, &_symbols_processed);
4364 Atomic::add(symbols_removed, &_symbols_removed);
4365 }
4366 }
4367
4368 size_t strings_processed() const { return (size_t)_strings_processed; }
4369 size_t strings_removed() const { return (size_t)_strings_removed; }
4370
4371 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4372 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4373 };
4374
4375 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4376 private:
4377 static Monitor* _lock;
4378
4379 BoolObjectClosure* const _is_alive;
4380 const bool _unloading_occurred;
4381 const uint _num_workers;
4382
4383 // Variables used to claim nmethods.
4384 nmethod* _first_nmethod;
4385 volatile nmethod* _claimed_nmethod;
4386
4387 // The list of nmethods that need to be processed by the second pass.
4388 volatile nmethod* _postponed_list;
4389 volatile uint _num_entered_barrier;
4390
4391 public:
4392 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4393 _is_alive(is_alive),
4394 _unloading_occurred(unloading_occurred),
4395 _num_workers(num_workers),
4396 _first_nmethod(NULL),
4397 _claimed_nmethod(NULL),
4398 _postponed_list(NULL),
4399 _num_entered_barrier(0)
4400 {
4401 nmethod::increase_unloading_clock();
4402 // Get first alive nmethod
4403 NMethodIterator iter = NMethodIterator();
4404 if(iter.next_alive()) {
4405 _first_nmethod = iter.method();
4406 }
4407 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4408 }
4409
4410 ~G1CodeCacheUnloadingTask() {
4411 CodeCache::verify_clean_inline_caches();
4412
4413 CodeCache::set_needs_cache_clean(false);
4414 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4415
4416 CodeCache::verify_icholder_relocations();
4417 }
4418
4419 private:
4420 void add_to_postponed_list(nmethod* nm) {
4421 nmethod* old;
4422 do {
4423 old = (nmethod*)_postponed_list;
4424 nm->set_unloading_next(old);
4425 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4426 }
4427
4428 void clean_nmethod(nmethod* nm) {
4429 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4430
4431 if (postponed) {
4432 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4433 add_to_postponed_list(nm);
4434 }
4435
4436 // Mark that this thread has been cleaned/unloaded.
4437 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4438 nm->set_unloading_clock(nmethod::global_unloading_clock());
4439 }
4440
4441 void clean_nmethod_postponed(nmethod* nm) {
4442 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4443 }
4444
4445 static const int MaxClaimNmethods = 16;
4446
4447 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4448 nmethod* first;
4449 NMethodIterator last;
4450
4451 do {
4452 *num_claimed_nmethods = 0;
4453
4454 first = (nmethod*)_claimed_nmethod;
4455 last = NMethodIterator(first);
4456
4457 if (first != NULL) {
4458
4459 for (int i = 0; i < MaxClaimNmethods; i++) {
4460 if (!last.next_alive()) {
4461 break;
4462 }
4463 claimed_nmethods[i] = last.method();
4464 (*num_claimed_nmethods)++;
4465 }
4466 }
4467
4468 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4469 }
4470
4471 nmethod* claim_postponed_nmethod() {
4472 nmethod* claim;
4473 nmethod* next;
4474
4475 do {
4476 claim = (nmethod*)_postponed_list;
4477 if (claim == NULL) {
4478 return NULL;
4479 }
4480
4481 next = claim->unloading_next();
4482
4483 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4484
4485 return claim;
4486 }
4487
4488 public:
4489 // Mark that we're done with the first pass of nmethod cleaning.
4490 void barrier_mark(uint worker_id) {
4491 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4492 _num_entered_barrier++;
4493 if (_num_entered_barrier == _num_workers) {
4494 ml.notify_all();
4495 }
4496 }
4497
4498 // See if we have to wait for the other workers to
4499 // finish their first-pass nmethod cleaning work.
4500 void barrier_wait(uint worker_id) {
4501 if (_num_entered_barrier < _num_workers) {
4502 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4503 while (_num_entered_barrier < _num_workers) {
4504 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4505 }
4506 }
4507 }
4508
4509 // Cleaning and unloading of nmethods. Some work has to be postponed
4510 // to the second pass, when we know which nmethods survive.
4511 void work_first_pass(uint worker_id) {
4512 // The first nmethods is claimed by the first worker.
4513 if (worker_id == 0 && _first_nmethod != NULL) {
4514 clean_nmethod(_first_nmethod);
4515 _first_nmethod = NULL;
4516 }
4517
4518 int num_claimed_nmethods;
4519 nmethod* claimed_nmethods[MaxClaimNmethods];
4520
4521 while (true) {
4522 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4523
4524 if (num_claimed_nmethods == 0) {
4525 break;
4526 }
4527
4528 for (int i = 0; i < num_claimed_nmethods; i++) {
4529 clean_nmethod(claimed_nmethods[i]);
4530 }
4531 }
4532 }
4533
4534 void work_second_pass(uint worker_id) {
4535 nmethod* nm;
4536 // Take care of postponed nmethods.
4537 while ((nm = claim_postponed_nmethod()) != NULL) {
4538 clean_nmethod_postponed(nm);
4539 }
4540 }
4541 };
4542
4543 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4544
4545 class G1KlassCleaningTask : public StackObj {
4546 BoolObjectClosure* _is_alive;
4547 volatile jint _clean_klass_tree_claimed;
4548 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4549
4550 public:
4551 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4552 _is_alive(is_alive),
4553 _clean_klass_tree_claimed(0),
4554 _klass_iterator() {
4555 }
4556
4557 private:
4558 bool claim_clean_klass_tree_task() {
4559 if (_clean_klass_tree_claimed) {
4560 return false;
4561 }
4562
4563 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4564 }
4565
4566 InstanceKlass* claim_next_klass() {
4567 Klass* klass;
4568 do {
4569 klass =_klass_iterator.next_klass();
4570 } while (klass != NULL && !klass->is_instance_klass());
4571
4572 // this can be null so don't call InstanceKlass::cast
4573 return static_cast<InstanceKlass*>(klass);
4574 }
4575
4576 public:
4577
4578 void clean_klass(InstanceKlass* ik) {
4579 ik->clean_weak_instanceklass_links(_is_alive);
4580 }
4581
4582 void work() {
4583 ResourceMark rm;
4584
4585 // One worker will clean the subklass/sibling klass tree.
4586 if (claim_clean_klass_tree_task()) {
4587 Klass::clean_subklass_tree(_is_alive);
4588 }
4589
4590 // All workers will help cleaning the classes,
4591 InstanceKlass* klass;
4592 while ((klass = claim_next_klass()) != NULL) {
4593 clean_klass(klass);
4594 }
4595 }
4596 };
4597
4598 // To minimize the remark pause times, the tasks below are done in parallel.
4599 class G1ParallelCleaningTask : public AbstractGangTask {
4600 private:
4601 G1StringSymbolTableUnlinkTask _string_symbol_task;
4602 G1CodeCacheUnloadingTask _code_cache_task;
4603 G1KlassCleaningTask _klass_cleaning_task;
4604
4605 public:
4606 // The constructor is run in the VMThread.
4607 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4608 AbstractGangTask("Parallel Cleaning"),
4609 _string_symbol_task(is_alive, process_strings, process_symbols),
4610 _code_cache_task(num_workers, is_alive, unloading_occurred),
4611 _klass_cleaning_task(is_alive) {
4612 }
4613
4614 // The parallel work done by all worker threads.
4615 void work(uint worker_id) {
4616 // Do first pass of code cache cleaning.
4617 _code_cache_task.work_first_pass(worker_id);
4618
4619 // Let the threads mark that the first pass is done.
4620 _code_cache_task.barrier_mark(worker_id);
4621
4622 // Clean the Strings and Symbols.
4623 _string_symbol_task.work(worker_id);
4624
4625 // Wait for all workers to finish the first code cache cleaning pass.
4626 _code_cache_task.barrier_wait(worker_id);
4627
4628 // Do the second code cache cleaning work, which realize on
4629 // the liveness information gathered during the first pass.
4630 _code_cache_task.work_second_pass(worker_id);
4631
4632 // Clean all klasses that were not unloaded.
4633 _klass_cleaning_task.work();
4634 }
4635 };
4636
4637
4638 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4639 bool process_strings,
4640 bool process_symbols,
4641 bool class_unloading_occurred) {
4642 uint n_workers = workers()->active_workers();
4643
4644 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4645 n_workers, class_unloading_occurred);
4646 workers()->run_task(&g1_unlink_task);
4647 }
4648
4649 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4650 bool process_strings, bool process_symbols) {
4651 {
4652 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4653 workers()->run_task(&g1_unlink_task);
4654 }
4655
4656 if (G1StringDedup::is_enabled()) {
4657 G1StringDedup::unlink(is_alive);
4658 }
4659 }
4660
4661 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4662 private:
4663 DirtyCardQueueSet* _queue;
4664 G1CollectedHeap* _g1h;
4665 public:
4666 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4667 _queue(queue), _g1h(g1h) { }
4668
4669 virtual void work(uint worker_id) {
4670 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4671 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4672
4673 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4674 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4675
4676 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4677 }
4678 };
4679
4680 void G1CollectedHeap::redirty_logged_cards() {
4681 double redirty_logged_cards_start = os::elapsedTime();
4682
4683 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4684 dirty_card_queue_set().reset_for_par_iteration();
4685 workers()->run_task(&redirty_task);
4686
4687 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4688 dcq.merge_bufferlists(&dirty_card_queue_set());
4689 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4690
4691 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4692 }
4693
4694 // Weak Reference Processing support
4695
4696 // An always "is_alive" closure that is used to preserve referents.
4697 // If the object is non-null then it's alive. Used in the preservation
4698 // of referent objects that are pointed to by reference objects
4699 // discovered by the CM ref processor.
4700 class G1AlwaysAliveClosure: public BoolObjectClosure {
4701 G1CollectedHeap* _g1;
4702 public:
4703 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4704 bool do_object_b(oop p) {
4705 if (p != NULL) {
4706 return true;
4707 }
4708 return false;
4709 }
4710 };
4711
4712 bool G1STWIsAliveClosure::do_object_b(oop p) {
4713 // An object is reachable if it is outside the collection set,
4714 // or is inside and copied.
4715 return !_g1->is_in_cset(p) || p->is_forwarded();
4716 }
4717
4718 // Non Copying Keep Alive closure
4719 class G1KeepAliveClosure: public OopClosure {
4720 G1CollectedHeap* _g1;
4721 public:
4722 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4723 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4724 void do_oop(oop* p) {
4725 oop obj = *p;
4726 assert(obj != NULL, "the caller should have filtered out NULL values");
4727
4728 const InCSetState cset_state = _g1->in_cset_state(obj);
4729 if (!cset_state.is_in_cset_or_humongous()) {
4730 return;
4731 }
4732 if (cset_state.is_in_cset()) {
4733 assert( obj->is_forwarded(), "invariant" );
4734 *p = obj->forwardee();
4735 } else {
4736 assert(!obj->is_forwarded(), "invariant" );
4737 assert(cset_state.is_humongous(),
4738 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4739 _g1->set_humongous_is_live(obj);
4740 }
4741 }
4742 };
4743
4744 // Copying Keep Alive closure - can be called from both
4745 // serial and parallel code as long as different worker
4746 // threads utilize different G1ParScanThreadState instances
4747 // and different queues.
4748
4749 class G1CopyingKeepAliveClosure: public OopClosure {
4750 G1CollectedHeap* _g1h;
4751 OopClosure* _copy_non_heap_obj_cl;
4752 G1ParScanThreadState* _par_scan_state;
4753
4754 public:
4755 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4756 OopClosure* non_heap_obj_cl,
4757 G1ParScanThreadState* pss):
4758 _g1h(g1h),
4759 _copy_non_heap_obj_cl(non_heap_obj_cl),
4760 _par_scan_state(pss)
4761 {}
4762
4763 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4764 virtual void do_oop( oop* p) { do_oop_work(p); }
4765
4766 template <class T> void do_oop_work(T* p) {
4767 oop obj = oopDesc::load_decode_heap_oop(p);
4768
4769 if (_g1h->is_in_cset_or_humongous(obj)) {
4770 // If the referent object has been forwarded (either copied
4771 // to a new location or to itself in the event of an
4772 // evacuation failure) then we need to update the reference
4773 // field and, if both reference and referent are in the G1
4774 // heap, update the RSet for the referent.
4775 //
4776 // If the referent has not been forwarded then we have to keep
4777 // it alive by policy. Therefore we have copy the referent.
4778 //
4779 // If the reference field is in the G1 heap then we can push
4780 // on the PSS queue. When the queue is drained (after each
4781 // phase of reference processing) the object and it's followers
4782 // will be copied, the reference field set to point to the
4783 // new location, and the RSet updated. Otherwise we need to
4784 // use the the non-heap or metadata closures directly to copy
4785 // the referent object and update the pointer, while avoiding
4786 // updating the RSet.
4787
4788 if (_g1h->is_in_g1_reserved(p)) {
4789 _par_scan_state->push_on_queue(p);
4790 } else {
4791 assert(!Metaspace::contains((const void*)p),
4792 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4793 _copy_non_heap_obj_cl->do_oop(p);
4794 }
4795 }
4796 }
4797 };
4798
4799 // Serial drain queue closure. Called as the 'complete_gc'
4800 // closure for each discovered list in some of the
4801 // reference processing phases.
4802
4803 class G1STWDrainQueueClosure: public VoidClosure {
4804 protected:
4805 G1CollectedHeap* _g1h;
4806 G1ParScanThreadState* _par_scan_state;
4807
4808 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4809
4810 public:
4811 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4812 _g1h(g1h),
4813 _par_scan_state(pss)
4814 { }
4815
4816 void do_void() {
4817 G1ParScanThreadState* const pss = par_scan_state();
4818 pss->trim_queue();
4819 }
4820 };
4821
4822 // Parallel Reference Processing closures
4823
4824 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4825 // processing during G1 evacuation pauses.
4826
4827 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4828 private:
4829 G1CollectedHeap* _g1h;
4830 G1ParScanThreadStateSet* _pss;
4831 RefToScanQueueSet* _queues;
4832 WorkGang* _workers;
4833 uint _active_workers;
4834
4835 public:
4836 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4837 G1ParScanThreadStateSet* per_thread_states,
4838 WorkGang* workers,
4839 RefToScanQueueSet *task_queues,
4840 uint n_workers) :
4841 _g1h(g1h),
4842 _pss(per_thread_states),
4843 _queues(task_queues),
4844 _workers(workers),
4845 _active_workers(n_workers)
4846 {
4847 assert(n_workers > 0, "shouldn't call this otherwise");
4848 }
4849
4850 // Executes the given task using concurrent marking worker threads.
4851 virtual void execute(ProcessTask& task);
4852 virtual void execute(EnqueueTask& task);
4853 };
4854
4855 // Gang task for possibly parallel reference processing
4856
4857 class G1STWRefProcTaskProxy: public AbstractGangTask {
4858 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4859 ProcessTask& _proc_task;
4860 G1CollectedHeap* _g1h;
4861 G1ParScanThreadStateSet* _pss;
4862 RefToScanQueueSet* _task_queues;
4863 ParallelTaskTerminator* _terminator;
4864
4865 public:
4866 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4867 G1CollectedHeap* g1h,
4868 G1ParScanThreadStateSet* per_thread_states,
4869 RefToScanQueueSet *task_queues,
4870 ParallelTaskTerminator* terminator) :
4871 AbstractGangTask("Process reference objects in parallel"),
4872 _proc_task(proc_task),
4873 _g1h(g1h),
4874 _pss(per_thread_states),
4875 _task_queues(task_queues),
4876 _terminator(terminator)
4877 {}
4878
4879 virtual void work(uint worker_id) {
4880 // The reference processing task executed by a single worker.
4881 ResourceMark rm;
4882 HandleMark hm;
4883
4884 G1STWIsAliveClosure is_alive(_g1h);
4885
4886 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4887 pss->set_ref_processor(NULL);
4888
4889 // Keep alive closure.
4890 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4891
4892 // Complete GC closure
4893 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4894
4895 // Call the reference processing task's work routine.
4896 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4897
4898 // Note we cannot assert that the refs array is empty here as not all
4899 // of the processing tasks (specifically phase2 - pp2_work) execute
4900 // the complete_gc closure (which ordinarily would drain the queue) so
4901 // the queue may not be empty.
4902 }
4903 };
4904
4905 // Driver routine for parallel reference processing.
4906 // Creates an instance of the ref processing gang
4907 // task and has the worker threads execute it.
4908 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4909 assert(_workers != NULL, "Need parallel worker threads.");
4910
4911 ParallelTaskTerminator terminator(_active_workers, _queues);
4912 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4913
4914 _workers->run_task(&proc_task_proxy);
4915 }
4916
4917 // Gang task for parallel reference enqueueing.
4918
4919 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4920 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4921 EnqueueTask& _enq_task;
4922
4923 public:
4924 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4925 AbstractGangTask("Enqueue reference objects in parallel"),
4926 _enq_task(enq_task)
4927 { }
4928
4929 virtual void work(uint worker_id) {
4930 _enq_task.work(worker_id);
4931 }
4932 };
4933
4934 // Driver routine for parallel reference enqueueing.
4935 // Creates an instance of the ref enqueueing gang
4936 // task and has the worker threads execute it.
4937
4938 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4939 assert(_workers != NULL, "Need parallel worker threads.");
4940
4941 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4942
4943 _workers->run_task(&enq_task_proxy);
4944 }
4945
4946 // End of weak reference support closures
4947
4948 // Abstract task used to preserve (i.e. copy) any referent objects
4949 // that are in the collection set and are pointed to by reference
4950 // objects discovered by the CM ref processor.
4951
4952 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4953 protected:
4954 G1CollectedHeap* _g1h;
4955 G1ParScanThreadStateSet* _pss;
4956 RefToScanQueueSet* _queues;
4957 ParallelTaskTerminator _terminator;
4958 uint _n_workers;
4959
4960 public:
4961 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4962 AbstractGangTask("ParPreserveCMReferents"),
4963 _g1h(g1h),
4964 _pss(per_thread_states),
4965 _queues(task_queues),
4966 _terminator(workers, _queues),
4967 _n_workers(workers)
4968 { }
4969
4970 void work(uint worker_id) {
4971 ResourceMark rm;
4972 HandleMark hm;
4973
4974 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4975 pss->set_ref_processor(NULL);
4976 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4977
4978 // Is alive closure
4979 G1AlwaysAliveClosure always_alive(_g1h);
4980
4981 // Copying keep alive closure. Applied to referent objects that need
4982 // to be copied.
4983 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4984
4985 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4986
4987 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4988 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4989
4990 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4991 // So this must be true - but assert just in case someone decides to
4992 // change the worker ids.
4993 assert(worker_id < limit, "sanity");
4994 assert(!rp->discovery_is_atomic(), "check this code");
4995
4996 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4997 for (uint idx = worker_id; idx < limit; idx += stride) {
4998 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4999
5000 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5001 while (iter.has_next()) {
5002 // Since discovery is not atomic for the CM ref processor, we
5003 // can see some null referent objects.
5004 iter.load_ptrs(DEBUG_ONLY(true));
5005 oop ref = iter.obj();
5006
5007 // This will filter nulls.
5008 if (iter.is_referent_alive()) {
5009 iter.make_referent_alive();
5010 }
5011 iter.move_to_next();
5012 }
5013 }
5014
5015 // Drain the queue - which may cause stealing
5016 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5017 drain_queue.do_void();
5018 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5019 assert(pss->queue_is_empty(), "should be");
5020 }
5021 };
5022
5023 void G1CollectedHeap::process_weak_jni_handles() {
5024 double ref_proc_start = os::elapsedTime();
5025
5026 G1STWIsAliveClosure is_alive(this);
5027 G1KeepAliveClosure keep_alive(this);
5028 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5029
5030 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5031 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5032 }
5033
5034 // Weak Reference processing during an evacuation pause (part 1).
5035 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5036 double ref_proc_start = os::elapsedTime();
5037
5038 ReferenceProcessor* rp = _ref_processor_stw;
5039 assert(rp->discovery_enabled(), "should have been enabled");
5040
5041 // Any reference objects, in the collection set, that were 'discovered'
5042 // by the CM ref processor should have already been copied (either by
5043 // applying the external root copy closure to the discovered lists, or
5044 // by following an RSet entry).
5045 //
5046 // But some of the referents, that are in the collection set, that these
5047 // reference objects point to may not have been copied: the STW ref
5048 // processor would have seen that the reference object had already
5049 // been 'discovered' and would have skipped discovering the reference,
5050 // but would not have treated the reference object as a regular oop.
5051 // As a result the copy closure would not have been applied to the
5052 // referent object.
5053 //
5054 // We need to explicitly copy these referent objects - the references
5055 // will be processed at the end of remarking.
5056 //
5057 // We also need to do this copying before we process the reference
5058 // objects discovered by the STW ref processor in case one of these
5059 // referents points to another object which is also referenced by an
5060 // object discovered by the STW ref processor.
5061
5062 uint no_of_gc_workers = workers()->active_workers();
5063
5064 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5065 per_thread_states,
5066 no_of_gc_workers,
5067 _task_queues);
5068
5069 workers()->run_task(&keep_cm_referents);
5070
5071 // Closure to test whether a referent is alive.
5072 G1STWIsAliveClosure is_alive(this);
5073
5074 // Even when parallel reference processing is enabled, the processing
5075 // of JNI refs is serial and performed serially by the current thread
5076 // rather than by a worker. The following PSS will be used for processing
5077 // JNI refs.
5078
5079 // Use only a single queue for this PSS.
5080 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5081 pss->set_ref_processor(NULL);
5082 assert(pss->queue_is_empty(), "pre-condition");
5083
5084 // Keep alive closure.
5085 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5086
5087 // Serial Complete GC closure
5088 G1STWDrainQueueClosure drain_queue(this, pss);
5089
5090 // Setup the soft refs policy...
5091 rp->setup_policy(false);
5092
5093 ReferenceProcessorStats stats;
5094 if (!rp->processing_is_mt()) {
5095 // Serial reference processing...
5096 stats = rp->process_discovered_references(&is_alive,
5097 &keep_alive,
5098 &drain_queue,
5099 NULL,
5100 _gc_timer_stw);
5101 } else {
5102 // Parallel reference processing
5103 assert(rp->num_q() == no_of_gc_workers, "sanity");
5104 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5105
5106 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5107 stats = rp->process_discovered_references(&is_alive,
5108 &keep_alive,
5109 &drain_queue,
5110 &par_task_executor,
5111 _gc_timer_stw);
5112 }
5113
5114 _gc_tracer_stw->report_gc_reference_stats(stats);
5115
5116 // We have completed copying any necessary live referent objects.
5117 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5118
5119 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5120 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5121 }
5122
5123 // Weak Reference processing during an evacuation pause (part 2).
5124 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5125 double ref_enq_start = os::elapsedTime();
5126
5127 ReferenceProcessor* rp = _ref_processor_stw;
5128 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5129
5130 // Now enqueue any remaining on the discovered lists on to
5131 // the pending list.
5132 if (!rp->processing_is_mt()) {
5133 // Serial reference processing...
5134 rp->enqueue_discovered_references();
5135 } else {
5136 // Parallel reference enqueueing
5137
5138 uint n_workers = workers()->active_workers();
5139
5140 assert(rp->num_q() == n_workers, "sanity");
5141 assert(n_workers <= rp->max_num_q(), "sanity");
5142
5143 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5144 rp->enqueue_discovered_references(&par_task_executor);
5145 }
5146
5147 rp->verify_no_references_recorded();
5148 assert(!rp->discovery_enabled(), "should have been disabled");
5149
5150 // FIXME
5151 // CM's reference processing also cleans up the string and symbol tables.
5152 // Should we do that here also? We could, but it is a serial operation
5153 // and could significantly increase the pause time.
5154
5155 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5156 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5157 }
5158
5159 void G1CollectedHeap::pre_evacuate_collection_set() {
5160 _expand_heap_after_alloc_failure = true;
5161 _evacuation_failed = false;
5162
5163 // Disable the hot card cache.
5164 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5165 hot_card_cache->reset_hot_cache_claimed_index();
5166 hot_card_cache->set_use_cache(false);
5167
5168 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5169 }
5170
5171 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5172 // Should G1EvacuationFailureALot be in effect for this GC?
5173 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5174
5175 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5176 double start_par_time_sec = os::elapsedTime();
5177 double end_par_time_sec;
5178
5179 {
5180 const uint n_workers = workers()->active_workers();
5181 G1RootProcessor root_processor(this, n_workers);
5182 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5183 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5184 if (collector_state()->during_initial_mark_pause()) {
5185 ClassLoaderDataGraph::clear_claimed_marks();
5186 }
5187
5188 // The individual threads will set their evac-failure closures.
5189 if (PrintTerminationStats) {
5190 print_termination_stats_hdr(gclog_or_tty);
5191 }
5192
5193 workers()->run_task(&g1_par_task);
5194 end_par_time_sec = os::elapsedTime();
5195
5196 // Closing the inner scope will execute the destructor
5197 // for the G1RootProcessor object. We record the current
5198 // elapsed time before closing the scope so that time
5199 // taken for the destructor is NOT included in the
5200 // reported parallel time.
5201 }
5202
5203 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5204
5205 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5206 phase_times->record_par_time(par_time_ms);
5207
5208 double code_root_fixup_time_ms =
5209 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5210 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5211 }
5212
5213 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5214 // Process any discovered reference objects - we have
5215 // to do this _before_ we retire the GC alloc regions
5216 // as we may have to copy some 'reachable' referent
5217 // objects (and their reachable sub-graphs) that were
5218 // not copied during the pause.
5219 if (g1_policy()->should_process_references()) {
5220 process_discovered_references(per_thread_states);
5221 } else {
5222 ref_processor_stw()->verify_no_references_recorded();
5223 process_weak_jni_handles();
5224 }
5225
5226 if (G1StringDedup::is_enabled()) {
5227 double fixup_start = os::elapsedTime();
5228
5229 G1STWIsAliveClosure is_alive(this);
5230 G1KeepAliveClosure keep_alive(this);
5231 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5232
5233 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5234 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5235 }
5236
5237 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5238
5239 if (evacuation_failed()) {
5240 restore_after_evac_failure();
5241
5242 // Reset the G1EvacuationFailureALot counters and flags
5243 // Note: the values are reset only when an actual
5244 // evacuation failure occurs.
5245 NOT_PRODUCT(reset_evacuation_should_fail();)
5246 }
5247
5248 // Enqueue any remaining references remaining on the STW
5249 // reference processor's discovered lists. We need to do
5250 // this after the card table is cleaned (and verified) as
5251 // the act of enqueueing entries on to the pending list
5252 // will log these updates (and dirty their associated
5253 // cards). We need these updates logged to update any
5254 // RSets.
5255 if (g1_policy()->should_process_references()) {
5256 enqueue_discovered_references(per_thread_states);
5257 } else {
5258 g1_policy()->phase_times()->record_ref_enq_time(0);
5259 }
5260
5261 _allocator->release_gc_alloc_regions(evacuation_info);
5262
5263 per_thread_states->flush();
5264
5265 record_obj_copy_mem_stats();
5266
5267 _survivor_evac_stats.adjust_desired_plab_sz();
5268 _old_evac_stats.adjust_desired_plab_sz();
5269
5270 // Reset and re-enable the hot card cache.
5271 // Note the counts for the cards in the regions in the
5272 // collection set are reset when the collection set is freed.
5273 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5274 hot_card_cache->reset_hot_cache();
5275 hot_card_cache->set_use_cache(true);
5276
5277 purge_code_root_memory();
5278
5279 redirty_logged_cards();
5280 #if defined(COMPILER2) || INCLUDE_JVMCI
5281 DerivedPointerTable::update_pointers();
5282 #endif
5283 }
5284
5285 void G1CollectedHeap::record_obj_copy_mem_stats() {
5286 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5287
5288 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5289 create_g1_evac_summary(&_old_evac_stats));
5290 }
5291
5292 void G1CollectedHeap::free_region(HeapRegion* hr,
5293 FreeRegionList* free_list,
5294 bool par,
5295 bool locked) {
5296 assert(!hr->is_free(), "the region should not be free");
5297 assert(!hr->is_empty(), "the region should not be empty");
5298 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5299 assert(free_list != NULL, "pre-condition");
5300
5301 if (G1VerifyBitmaps) {
5302 MemRegion mr(hr->bottom(), hr->end());
5303 concurrent_mark()->clearRangePrevBitmap(mr);
5304 }
5305
5306 // Clear the card counts for this region.
5307 // Note: we only need to do this if the region is not young
5308 // (since we don't refine cards in young regions).
5309 if (!hr->is_young()) {
5310 _cg1r->hot_card_cache()->reset_card_counts(hr);
5311 }
5312 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5313 free_list->add_ordered(hr);
5314 }
5315
5316 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5317 FreeRegionList* free_list,
5318 bool par) {
5319 assert(hr->is_humongous(), "this is only for humongous regions");
5320 assert(free_list != NULL, "pre-condition");
5321 hr->clear_humongous();
5322 free_region(hr, free_list, par);
5323 }
5324
5325 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5326 const HeapRegionSetCount& humongous_regions_removed) {
5327 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5328 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5329 _old_set.bulk_remove(old_regions_removed);
5330 _humongous_set.bulk_remove(humongous_regions_removed);
5331 }
5332
5333 }
5334
5335 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5336 assert(list != NULL, "list can't be null");
5337 if (!list->is_empty()) {
5338 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5339 _hrm.insert_list_into_free_list(list);
5340 }
5341 }
5342
5343 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5344 decrease_used(bytes);
5345 }
5346
5347 class G1ParCleanupCTTask : public AbstractGangTask {
5348 G1SATBCardTableModRefBS* _ct_bs;
5349 G1CollectedHeap* _g1h;
5350 HeapRegion* volatile _su_head;
5351 public:
5352 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5353 G1CollectedHeap* g1h) :
5354 AbstractGangTask("G1 Par Cleanup CT Task"),
5355 _ct_bs(ct_bs), _g1h(g1h) { }
5356
5357 void work(uint worker_id) {
5358 HeapRegion* r;
5359 while (r = _g1h->pop_dirty_cards_region()) {
5360 clear_cards(r);
5361 }
5362 }
5363
5364 void clear_cards(HeapRegion* r) {
5365 // Cards of the survivors should have already been dirtied.
5366 if (!r->is_survivor()) {
5367 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5368 }
5369 }
5370 };
5371
5372 #ifndef PRODUCT
5373 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5374 G1CollectedHeap* _g1h;
5375 G1SATBCardTableModRefBS* _ct_bs;
5376 public:
5377 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5378 : _g1h(g1h), _ct_bs(ct_bs) { }
5379 virtual bool doHeapRegion(HeapRegion* r) {
5380 if (r->is_survivor()) {
5381 _g1h->verify_dirty_region(r);
5382 } else {
5383 _g1h->verify_not_dirty_region(r);
5384 }
5385 return false;
5386 }
5387 };
5388
5389 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5390 // All of the region should be clean.
5391 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5392 MemRegion mr(hr->bottom(), hr->end());
5393 ct_bs->verify_not_dirty_region(mr);
5394 }
5395
5396 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5397 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5398 // dirty allocated blocks as they allocate them. The thread that
5399 // retires each region and replaces it with a new one will do a
5400 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5401 // not dirty that area (one less thing to have to do while holding
5402 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5403 // is dirty.
5404 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5405 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5406 if (hr->is_young()) {
5407 ct_bs->verify_g1_young_region(mr);
5408 } else {
5409 ct_bs->verify_dirty_region(mr);
5410 }
5411 }
5412
5413 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5414 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5415 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5416 verify_dirty_region(hr);
5417 }
5418 }
5419
5420 void G1CollectedHeap::verify_dirty_young_regions() {
5421 verify_dirty_young_list(_young_list->first_region());
5422 }
5423
5424 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5425 HeapWord* tams, HeapWord* end) {
5426 guarantee(tams <= end,
5427 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5428 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5429 if (result < end) {
5430 gclog_or_tty->cr();
5431 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5432 bitmap_name, p2i(result));
5433 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5434 bitmap_name, p2i(tams), p2i(end));
5435 return false;
5436 }
5437 return true;
5438 }
5439
5440 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5441 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5442 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5443
5444 HeapWord* bottom = hr->bottom();
5445 HeapWord* ptams = hr->prev_top_at_mark_start();
5446 HeapWord* ntams = hr->next_top_at_mark_start();
5447 HeapWord* end = hr->end();
5448
5449 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5450
5451 bool res_n = true;
5452 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5453 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5454 // if we happen to be in that state.
5455 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5456 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5457 }
5458 if (!res_p || !res_n) {
5459 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5460 HR_FORMAT_PARAMS(hr));
5461 gclog_or_tty->print_cr("#### Caller: %s", caller);
5462 return false;
5463 }
5464 return true;
5465 }
5466
5467 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5468 if (!G1VerifyBitmaps) return;
5469
5470 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5471 }
5472
5473 class G1VerifyBitmapClosure : public HeapRegionClosure {
5474 private:
5475 const char* _caller;
5476 G1CollectedHeap* _g1h;
5477 bool _failures;
5478
5479 public:
5480 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5481 _caller(caller), _g1h(g1h), _failures(false) { }
5482
5483 bool failures() { return _failures; }
5484
5485 virtual bool doHeapRegion(HeapRegion* hr) {
5486 bool result = _g1h->verify_bitmaps(_caller, hr);
5487 if (!result) {
5488 _failures = true;
5489 }
5490 return false;
5491 }
5492 };
5493
5494 void G1CollectedHeap::check_bitmaps(const char* caller) {
5495 if (!G1VerifyBitmaps) return;
5496
5497 G1VerifyBitmapClosure cl(caller, this);
5498 heap_region_iterate(&cl);
5499 guarantee(!cl.failures(), "bitmap verification");
5500 }
5501
5502 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5503 private:
5504 bool _failures;
5505 public:
5506 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5507
5508 virtual bool doHeapRegion(HeapRegion* hr) {
5509 uint i = hr->hrm_index();
5510 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5511 if (hr->is_humongous()) {
5512 if (hr->in_collection_set()) {
5513 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5514 _failures = true;
5515 return true;
5516 }
5517 if (cset_state.is_in_cset()) {
5518 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5519 _failures = true;
5520 return true;
5521 }
5522 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5523 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5524 _failures = true;
5525 return true;
5526 }
5527 } else {
5528 if (cset_state.is_humongous()) {
5529 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5530 _failures = true;
5531 return true;
5532 }
5533 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5534 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5535 hr->in_collection_set(), cset_state.value(), i);
5536 _failures = true;
5537 return true;
5538 }
5539 if (cset_state.is_in_cset()) {
5540 if (hr->is_young() != (cset_state.is_young())) {
5541 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5542 hr->is_young(), cset_state.value(), i);
5543 _failures = true;
5544 return true;
5545 }
5546 if (hr->is_old() != (cset_state.is_old())) {
5547 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5548 hr->is_old(), cset_state.value(), i);
5549 _failures = true;
5550 return true;
5551 }
5552 }
5553 }
5554 return false;
5555 }
5556
5557 bool failures() const { return _failures; }
5558 };
5559
5560 bool G1CollectedHeap::check_cset_fast_test() {
5561 G1CheckCSetFastTableClosure cl;
5562 _hrm.iterate(&cl);
5563 return !cl.failures();
5564 }
5565 #endif // PRODUCT
5566
5567 void G1CollectedHeap::cleanUpCardTable() {
5568 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5569 double start = os::elapsedTime();
5570
5571 {
5572 // Iterate over the dirty cards region list.
5573 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5574
5575 workers()->run_task(&cleanup_task);
5576 #ifndef PRODUCT
5577 if (G1VerifyCTCleanup || VerifyAfterGC) {
5578 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5579 heap_region_iterate(&cleanup_verifier);
5580 }
5581 #endif
5582 }
5583
5584 double elapsed = os::elapsedTime() - start;
5585 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5586 }
5587
5588 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5589 size_t pre_used = 0;
5590 FreeRegionList local_free_list("Local List for CSet Freeing");
5591
5592 double young_time_ms = 0.0;
5593 double non_young_time_ms = 0.0;
5594
5595 // Since the collection set is a superset of the the young list,
5596 // all we need to do to clear the young list is clear its
5597 // head and length, and unlink any young regions in the code below
5598 _young_list->clear();
5599
5600 G1CollectorPolicy* policy = g1_policy();
5601
5602 double start_sec = os::elapsedTime();
5603 bool non_young = true;
5604
5605 HeapRegion* cur = cs_head;
5606 int age_bound = -1;
5607 size_t rs_lengths = 0;
5608
5609 while (cur != NULL) {
5610 assert(!is_on_master_free_list(cur), "sanity");
5611 if (non_young) {
5612 if (cur->is_young()) {
5613 double end_sec = os::elapsedTime();
5614 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5615 non_young_time_ms += elapsed_ms;
5616
5617 start_sec = os::elapsedTime();
5618 non_young = false;
5619 }
5620 } else {
5621 if (!cur->is_young()) {
5622 double end_sec = os::elapsedTime();
5623 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5624 young_time_ms += elapsed_ms;
5625
5626 start_sec = os::elapsedTime();
5627 non_young = true;
5628 }
5629 }
5630
5631 rs_lengths += cur->rem_set()->occupied_locked();
5632
5633 HeapRegion* next = cur->next_in_collection_set();
5634 assert(cur->in_collection_set(), "bad CS");
5635 cur->set_next_in_collection_set(NULL);
5636 clear_in_cset(cur);
5637
5638 if (cur->is_young()) {
5639 int index = cur->young_index_in_cset();
5640 assert(index != -1, "invariant");
5641 assert((uint) index < policy->young_cset_region_length(), "invariant");
5642 size_t words_survived = surviving_young_words[index];
5643 cur->record_surv_words_in_group(words_survived);
5644
5645 // At this point the we have 'popped' cur from the collection set
5646 // (linked via next_in_collection_set()) but it is still in the
5647 // young list (linked via next_young_region()). Clear the
5648 // _next_young_region field.
5649 cur->set_next_young_region(NULL);
5650 } else {
5651 int index = cur->young_index_in_cset();
5652 assert(index == -1, "invariant");
5653 }
5654
5655 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5656 (!cur->is_young() && cur->young_index_in_cset() == -1),
5657 "invariant" );
5658
5659 if (!cur->evacuation_failed()) {
5660 MemRegion used_mr = cur->used_region();
5661
5662 // And the region is empty.
5663 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5664 pre_used += cur->used();
5665 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5666 } else {
5667 cur->uninstall_surv_rate_group();
5668 if (cur->is_young()) {
5669 cur->set_young_index_in_cset(-1);
5670 }
5671 cur->set_evacuation_failed(false);
5672 // When moving a young gen region to old gen, we "allocate" that whole region
5673 // there. This is in addition to any already evacuated objects. Notify the
5674 // policy about that.
5675 // Old gen regions do not cause an additional allocation: both the objects
5676 // still in the region and the ones already moved are accounted for elsewhere.
5677 if (cur->is_young()) {
5678 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5679 }
5680 // The region is now considered to be old.
5681 cur->set_old();
5682 // Do some allocation statistics accounting. Regions that failed evacuation
5683 // are always made old, so there is no need to update anything in the young
5684 // gen statistics, but we need to update old gen statistics.
5685 size_t used_words = cur->marked_bytes() / HeapWordSize;
5686 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5687 _old_set.add(cur);
5688 evacuation_info.increment_collectionset_used_after(cur->used());
5689 }
5690 cur = next;
5691 }
5692
5693 evacuation_info.set_regions_freed(local_free_list.length());
5694 policy->record_max_rs_lengths(rs_lengths);
5695 policy->cset_regions_freed();
5696
5697 double end_sec = os::elapsedTime();
5698 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5699
5700 if (non_young) {
5701 non_young_time_ms += elapsed_ms;
5702 } else {
5703 young_time_ms += elapsed_ms;
5704 }
5705
5706 prepend_to_freelist(&local_free_list);
5707 decrement_summary_bytes(pre_used);
5708 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5709 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5710 }
5711
5712 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5713 private:
5714 FreeRegionList* _free_region_list;
5715 HeapRegionSet* _proxy_set;
5716 HeapRegionSetCount _humongous_regions_removed;
5717 size_t _freed_bytes;
5718 public:
5719
5720 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5721 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5722 }
5723
5724 virtual bool doHeapRegion(HeapRegion* r) {
5725 if (!r->is_starts_humongous()) {
5726 return false;
5727 }
5728
5729 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5730
5731 oop obj = (oop)r->bottom();
5732 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5733
5734 // The following checks whether the humongous object is live are sufficient.
5735 // The main additional check (in addition to having a reference from the roots
5736 // or the young gen) is whether the humongous object has a remembered set entry.
5737 //
5738 // A humongous object cannot be live if there is no remembered set for it
5739 // because:
5740 // - there can be no references from within humongous starts regions referencing
5741 // the object because we never allocate other objects into them.
5742 // (I.e. there are no intra-region references that may be missed by the
5743 // remembered set)
5744 // - as soon there is a remembered set entry to the humongous starts region
5745 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5746 // until the end of a concurrent mark.
5747 //
5748 // It is not required to check whether the object has been found dead by marking
5749 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5750 // all objects allocated during that time are considered live.
5751 // SATB marking is even more conservative than the remembered set.
5752 // So if at this point in the collection there is no remembered set entry,
5753 // nobody has a reference to it.
5754 // At the start of collection we flush all refinement logs, and remembered sets
5755 // are completely up-to-date wrt to references to the humongous object.
5756 //
5757 // Other implementation considerations:
5758 // - never consider object arrays at this time because they would pose
5759 // considerable effort for cleaning up the the remembered sets. This is
5760 // required because stale remembered sets might reference locations that
5761 // are currently allocated into.
5762 uint region_idx = r->hrm_index();
5763 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5764 !r->rem_set()->is_empty()) {
5765
5766 if (G1TraceEagerReclaimHumongousObjects) {
5767 gclog_or_tty->print_cr("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5768 region_idx,
5769 (size_t)obj->size() * HeapWordSize,
5770 p2i(r->bottom()),
5771 r->rem_set()->occupied(),
5772 r->rem_set()->strong_code_roots_list_length(),
5773 next_bitmap->isMarked(r->bottom()),
5774 g1h->is_humongous_reclaim_candidate(region_idx),
5775 obj->is_typeArray()
5776 );
5777 }
5778
5779 return false;
5780 }
5781
5782 guarantee(obj->is_typeArray(),
5783 "Only eagerly reclaiming type arrays is supported, but the object "
5784 PTR_FORMAT " is not.", p2i(r->bottom()));
5785
5786 if (G1TraceEagerReclaimHumongousObjects) {
5787 gclog_or_tty->print_cr("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5788 region_idx,
5789 (size_t)obj->size() * HeapWordSize,
5790 p2i(r->bottom()),
5791 r->rem_set()->occupied(),
5792 r->rem_set()->strong_code_roots_list_length(),
5793 next_bitmap->isMarked(r->bottom()),
5794 g1h->is_humongous_reclaim_candidate(region_idx),
5795 obj->is_typeArray()
5796 );
5797 }
5798 // Need to clear mark bit of the humongous object if already set.
5799 if (next_bitmap->isMarked(r->bottom())) {
5800 next_bitmap->clear(r->bottom());
5801 }
5802 do {
5803 HeapRegion* next = g1h->next_region_in_humongous(r);
5804 _freed_bytes += r->used();
5805 r->set_containing_set(NULL);
5806 _humongous_regions_removed.increment(1u, r->capacity());
5807 g1h->free_humongous_region(r, _free_region_list, false);
5808 r = next;
5809 } while (r != NULL);
5810
5811 return false;
5812 }
5813
5814 HeapRegionSetCount& humongous_free_count() {
5815 return _humongous_regions_removed;
5816 }
5817
5818 size_t bytes_freed() const {
5819 return _freed_bytes;
5820 }
5821
5822 size_t humongous_reclaimed() const {
5823 return _humongous_regions_removed.length();
5824 }
5825 };
5826
5827 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5828 assert_at_safepoint(true);
5829
5830 if (!G1EagerReclaimHumongousObjects ||
5831 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5832 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5833 return;
5834 }
5835
5836 double start_time = os::elapsedTime();
5837
5838 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5839
5840 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5841 heap_region_iterate(&cl);
5842
5843 HeapRegionSetCount empty_set;
5844 remove_from_old_sets(empty_set, cl.humongous_free_count());
5845
5846 G1HRPrinter* hrp = hr_printer();
5847 if (hrp->is_active()) {
5848 FreeRegionListIterator iter(&local_cleanup_list);
5849 while (iter.more_available()) {
5850 HeapRegion* hr = iter.get_next();
5851 hrp->cleanup(hr);
5852 }
5853 }
5854
5855 prepend_to_freelist(&local_cleanup_list);
5856 decrement_summary_bytes(cl.bytes_freed());
5857
5858 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5859 cl.humongous_reclaimed());
5860 }
5861
5862 // This routine is similar to the above but does not record
5863 // any policy statistics or update free lists; we are abandoning
5864 // the current incremental collection set in preparation of a
5865 // full collection. After the full GC we will start to build up
5866 // the incremental collection set again.
5867 // This is only called when we're doing a full collection
5868 // and is immediately followed by the tearing down of the young list.
5869
5870 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5871 HeapRegion* cur = cs_head;
5872
5873 while (cur != NULL) {
5874 HeapRegion* next = cur->next_in_collection_set();
5875 assert(cur->in_collection_set(), "bad CS");
5876 cur->set_next_in_collection_set(NULL);
5877 clear_in_cset(cur);
5878 cur->set_young_index_in_cset(-1);
5879 cur = next;
5880 }
5881 }
5882
5883 void G1CollectedHeap::set_free_regions_coming() {
5884 if (G1ConcRegionFreeingVerbose) {
5885 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5886 "setting free regions coming");
5887 }
5888
5889 assert(!free_regions_coming(), "pre-condition");
5890 _free_regions_coming = true;
5891 }
5892
5893 void G1CollectedHeap::reset_free_regions_coming() {
5894 assert(free_regions_coming(), "pre-condition");
5895
5896 {
5897 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5898 _free_regions_coming = false;
5899 SecondaryFreeList_lock->notify_all();
5900 }
5901
5902 if (G1ConcRegionFreeingVerbose) {
5903 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5904 "reset free regions coming");
5905 }
5906 }
5907
5908 void G1CollectedHeap::wait_while_free_regions_coming() {
5909 // Most of the time we won't have to wait, so let's do a quick test
5910 // first before we take the lock.
5911 if (!free_regions_coming()) {
5912 return;
5913 }
5914
5915 if (G1ConcRegionFreeingVerbose) {
5916 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5917 "waiting for free regions");
5918 }
5919
5920 {
5921 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5922 while (free_regions_coming()) {
5923 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5924 }
5925 }
5926
5927 if (G1ConcRegionFreeingVerbose) {
5928 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5929 "done waiting for free regions");
5930 }
5931 }
5932
5933 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5934 return _allocator->is_retained_old_region(hr);
5935 }
5936
5937 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5938 _young_list->push_region(hr);
5939 }
5940
5941 class NoYoungRegionsClosure: public HeapRegionClosure {
5942 private:
5943 bool _success;
5944 public:
5945 NoYoungRegionsClosure() : _success(true) { }
5946 bool doHeapRegion(HeapRegion* r) {
5947 if (r->is_young()) {
5948 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5949 p2i(r->bottom()), p2i(r->end()));
5950 _success = false;
5951 }
5952 return false;
5953 }
5954 bool success() { return _success; }
5955 };
5956
5957 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5958 bool ret = _young_list->check_list_empty(check_sample);
5959
5960 if (check_heap) {
5961 NoYoungRegionsClosure closure;
5962 heap_region_iterate(&closure);
5963 ret = ret && closure.success();
5964 }
5965
5966 return ret;
5967 }
5968
5969 class TearDownRegionSetsClosure : public HeapRegionClosure {
5970 private:
5971 HeapRegionSet *_old_set;
5972
5973 public:
5974 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5975
5976 bool doHeapRegion(HeapRegion* r) {
5977 if (r->is_old()) {
5978 _old_set->remove(r);
5979 } else {
5980 // We ignore free regions, we'll empty the free list afterwards.
5981 // We ignore young regions, we'll empty the young list afterwards.
5982 // We ignore humongous regions, we're not tearing down the
5983 // humongous regions set.
5984 assert(r->is_free() || r->is_young() || r->is_humongous(),
5985 "it cannot be another type");
5986 }
5987 return false;
5988 }
5989
5990 ~TearDownRegionSetsClosure() {
5991 assert(_old_set->is_empty(), "post-condition");
5992 }
5993 };
5994
5995 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5996 assert_at_safepoint(true /* should_be_vm_thread */);
5997
5998 if (!free_list_only) {
5999 TearDownRegionSetsClosure cl(&_old_set);
6000 heap_region_iterate(&cl);
6001
6002 // Note that emptying the _young_list is postponed and instead done as
6003 // the first step when rebuilding the regions sets again. The reason for
6004 // this is that during a full GC string deduplication needs to know if
6005 // a collected region was young or old when the full GC was initiated.
6006 }
6007 _hrm.remove_all_free_regions();
6008 }
6009
6010 void G1CollectedHeap::increase_used(size_t bytes) {
6011 _summary_bytes_used += bytes;
6012 }
6013
6014 void G1CollectedHeap::decrease_used(size_t bytes) {
6015 assert(_summary_bytes_used >= bytes,
6016 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6017 _summary_bytes_used, bytes);
6018 _summary_bytes_used -= bytes;
6019 }
6020
6021 void G1CollectedHeap::set_used(size_t bytes) {
6022 _summary_bytes_used = bytes;
6023 }
6024
6025 class RebuildRegionSetsClosure : public HeapRegionClosure {
6026 private:
6027 bool _free_list_only;
6028 HeapRegionSet* _old_set;
6029 HeapRegionManager* _hrm;
6030 size_t _total_used;
6031
6032 public:
6033 RebuildRegionSetsClosure(bool free_list_only,
6034 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6035 _free_list_only(free_list_only),
6036 _old_set(old_set), _hrm(hrm), _total_used(0) {
6037 assert(_hrm->num_free_regions() == 0, "pre-condition");
6038 if (!free_list_only) {
6039 assert(_old_set->is_empty(), "pre-condition");
6040 }
6041 }
6042
6043 bool doHeapRegion(HeapRegion* r) {
6044 if (r->is_empty()) {
6045 // Add free regions to the free list
6046 r->set_free();
6047 r->set_allocation_context(AllocationContext::system());
6048 _hrm->insert_into_free_list(r);
6049 } else if (!_free_list_only) {
6050 assert(!r->is_young(), "we should not come across young regions");
6051
6052 if (r->is_humongous()) {
6053 // We ignore humongous regions. We left the humongous set unchanged.
6054 } else {
6055 // Objects that were compacted would have ended up on regions
6056 // that were previously old or free. Archive regions (which are
6057 // old) will not have been touched.
6058 assert(r->is_free() || r->is_old(), "invariant");
6059 // We now consider them old, so register as such. Leave
6060 // archive regions set that way, however, while still adding
6061 // them to the old set.
6062 if (!r->is_archive()) {
6063 r->set_old();
6064 }
6065 _old_set->add(r);
6066 }
6067 _total_used += r->used();
6068 }
6069
6070 return false;
6071 }
6072
6073 size_t total_used() {
6074 return _total_used;
6075 }
6076 };
6077
6078 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6079 assert_at_safepoint(true /* should_be_vm_thread */);
6080
6081 if (!free_list_only) {
6082 _young_list->empty_list();
6083 }
6084
6085 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6086 heap_region_iterate(&cl);
6087
6088 if (!free_list_only) {
6089 set_used(cl.total_used());
6090 if (_archive_allocator != NULL) {
6091 _archive_allocator->clear_used();
6092 }
6093 }
6094 assert(used_unlocked() == recalculate_used(),
6095 "inconsistent used_unlocked(), "
6096 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6097 used_unlocked(), recalculate_used());
6098 }
6099
6100 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6101 _refine_cte_cl->set_concurrent(concurrent);
6102 }
6103
6104 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6105 HeapRegion* hr = heap_region_containing(p);
6106 return hr->is_in(p);
6107 }
6108
6109 // Methods for the mutator alloc region
6110
6111 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6112 bool force) {
6113 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6114 assert(!force || g1_policy()->can_expand_young_list(),
6115 "if force is true we should be able to expand the young list");
6116 bool young_list_full = g1_policy()->is_young_list_full();
6117 if (force || !young_list_full) {
6118 HeapRegion* new_alloc_region = new_region(word_size,
6119 false /* is_old */,
6120 false /* do_expand */);
6121 if (new_alloc_region != NULL) {
6122 set_region_short_lived_locked(new_alloc_region);
6123 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6124 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6125 return new_alloc_region;
6126 }
6127 }
6128 return NULL;
6129 }
6130
6131 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6132 size_t allocated_bytes) {
6133 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6134 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6135
6136 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6137 increase_used(allocated_bytes);
6138 _hr_printer.retire(alloc_region);
6139 // We update the eden sizes here, when the region is retired,
6140 // instead of when it's allocated, since this is the point that its
6141 // used space has been recored in _summary_bytes_used.
6142 g1mm()->update_eden_size();
6143 }
6144
6145 // Methods for the GC alloc regions
6146
6147 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6148 uint count,
6149 InCSetState dest) {
6150 assert(FreeList_lock->owned_by_self(), "pre-condition");
6151
6152 if (count < g1_policy()->max_regions(dest)) {
6153 const bool is_survivor = (dest.is_young());
6154 HeapRegion* new_alloc_region = new_region(word_size,
6155 !is_survivor,
6156 true /* do_expand */);
6157 if (new_alloc_region != NULL) {
6158 // We really only need to do this for old regions given that we
6159 // should never scan survivors. But it doesn't hurt to do it
6160 // for survivors too.
6161 new_alloc_region->record_timestamp();
6162 if (is_survivor) {
6163 new_alloc_region->set_survivor();
6164 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6165 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6166 } else {
6167 new_alloc_region->set_old();
6168 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6169 check_bitmaps("Old Region Allocation", new_alloc_region);
6170 }
6171 bool during_im = collector_state()->during_initial_mark_pause();
6172 new_alloc_region->note_start_of_copying(during_im);
6173 return new_alloc_region;
6174 }
6175 }
6176 return NULL;
6177 }
6178
6179 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6180 size_t allocated_bytes,
6181 InCSetState dest) {
6182 bool during_im = collector_state()->during_initial_mark_pause();
6183 alloc_region->note_end_of_copying(during_im);
6184 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6185 if (dest.is_young()) {
6186 young_list()->add_survivor_region(alloc_region);
6187 } else {
6188 _old_set.add(alloc_region);
6189 }
6190 _hr_printer.retire(alloc_region);
6191 }
6192
6193 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6194 bool expanded = false;
6195 uint index = _hrm.find_highest_free(&expanded);
6196
6197 if (index != G1_NO_HRM_INDEX) {
6198 if (expanded) {
6199 ergo_verbose1(ErgoHeapSizing,
6200 "attempt heap expansion",
6201 ergo_format_reason("requested address range outside heap bounds")
6202 ergo_format_byte("region size"),
6203 HeapRegion::GrainWords * HeapWordSize);
6204 }
6205 _hrm.allocate_free_regions_starting_at(index, 1);
6206 return region_at(index);
6207 }
6208 return NULL;
6209 }
6210
6211 // Heap region set verification
6212
6213 class VerifyRegionListsClosure : public HeapRegionClosure {
6214 private:
6215 HeapRegionSet* _old_set;
6216 HeapRegionSet* _humongous_set;
6217 HeapRegionManager* _hrm;
6218
6219 public:
6220 HeapRegionSetCount _old_count;
6221 HeapRegionSetCount _humongous_count;
6222 HeapRegionSetCount _free_count;
6223
6224 VerifyRegionListsClosure(HeapRegionSet* old_set,
6225 HeapRegionSet* humongous_set,
6226 HeapRegionManager* hrm) :
6227 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6228 _old_count(), _humongous_count(), _free_count(){ }
6229
6230 bool doHeapRegion(HeapRegion* hr) {
6231 if (hr->is_young()) {
6232 // TODO
6233 } else if (hr->is_humongous()) {
6234 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6235 _humongous_count.increment(1u, hr->capacity());
6236 } else if (hr->is_empty()) {
6237 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6238 _free_count.increment(1u, hr->capacity());
6239 } else if (hr->is_old()) {
6240 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6241 _old_count.increment(1u, hr->capacity());
6242 } else {
6243 // There are no other valid region types. Check for one invalid
6244 // one we can identify: pinned without old or humongous set.
6245 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6246 ShouldNotReachHere();
6247 }
6248 return false;
6249 }
6250
6251 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6252 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6253 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6254 old_set->total_capacity_bytes(), _old_count.capacity());
6255
6256 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6257 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6258 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6259
6260 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());
6261 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6262 free_list->total_capacity_bytes(), _free_count.capacity());
6263 }
6264 };
6265
6266 void G1CollectedHeap::verify_region_sets() {
6267 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6268
6269 // First, check the explicit lists.
6270 _hrm.verify();
6271 {
6272 // Given that a concurrent operation might be adding regions to
6273 // the secondary free list we have to take the lock before
6274 // verifying it.
6275 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6276 _secondary_free_list.verify_list();
6277 }
6278
6279 // If a concurrent region freeing operation is in progress it will
6280 // be difficult to correctly attributed any free regions we come
6281 // across to the correct free list given that they might belong to
6282 // one of several (free_list, secondary_free_list, any local lists,
6283 // etc.). So, if that's the case we will skip the rest of the
6284 // verification operation. Alternatively, waiting for the concurrent
6285 // operation to complete will have a non-trivial effect on the GC's
6286 // operation (no concurrent operation will last longer than the
6287 // interval between two calls to verification) and it might hide
6288 // any issues that we would like to catch during testing.
6289 if (free_regions_coming()) {
6290 return;
6291 }
6292
6293 // Make sure we append the secondary_free_list on the free_list so
6294 // that all free regions we will come across can be safely
6295 // attributed to the free_list.
6296 append_secondary_free_list_if_not_empty_with_lock();
6297
6298 // Finally, make sure that the region accounting in the lists is
6299 // consistent with what we see in the heap.
6300
6301 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6302 heap_region_iterate(&cl);
6303 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6304 }
6305
6306 // Optimized nmethod scanning
6307
6308 class RegisterNMethodOopClosure: public OopClosure {
6309 G1CollectedHeap* _g1h;
6310 nmethod* _nm;
6311
6312 template <class T> void do_oop_work(T* p) {
6313 T heap_oop = oopDesc::load_heap_oop(p);
6314 if (!oopDesc::is_null(heap_oop)) {
6315 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6316 HeapRegion* hr = _g1h->heap_region_containing(obj);
6317 assert(!hr->is_continues_humongous(),
6318 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6319 " starting at " HR_FORMAT,
6320 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6321
6322 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6323 hr->add_strong_code_root_locked(_nm);
6324 }
6325 }
6326
6327 public:
6328 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6329 _g1h(g1h), _nm(nm) {}
6330
6331 void do_oop(oop* p) { do_oop_work(p); }
6332 void do_oop(narrowOop* p) { do_oop_work(p); }
6333 };
6334
6335 class UnregisterNMethodOopClosure: public OopClosure {
6336 G1CollectedHeap* _g1h;
6337 nmethod* _nm;
6338
6339 template <class T> void do_oop_work(T* p) {
6340 T heap_oop = oopDesc::load_heap_oop(p);
6341 if (!oopDesc::is_null(heap_oop)) {
6342 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6343 HeapRegion* hr = _g1h->heap_region_containing(obj);
6344 assert(!hr->is_continues_humongous(),
6345 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6346 " starting at " HR_FORMAT,
6347 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6348
6349 hr->remove_strong_code_root(_nm);
6350 }
6351 }
6352
6353 public:
6354 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6355 _g1h(g1h), _nm(nm) {}
6356
6357 void do_oop(oop* p) { do_oop_work(p); }
6358 void do_oop(narrowOop* p) { do_oop_work(p); }
6359 };
6360
6361 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6362 CollectedHeap::register_nmethod(nm);
6363
6364 guarantee(nm != NULL, "sanity");
6365 RegisterNMethodOopClosure reg_cl(this, nm);
6366 nm->oops_do(®_cl);
6367 }
6368
6369 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6370 CollectedHeap::unregister_nmethod(nm);
6371
6372 guarantee(nm != NULL, "sanity");
6373 UnregisterNMethodOopClosure reg_cl(this, nm);
6374 nm->oops_do(®_cl, true);
6375 }
6376
6377 void G1CollectedHeap::purge_code_root_memory() {
6378 double purge_start = os::elapsedTime();
6379 G1CodeRootSet::purge();
6380 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6381 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6382 }
6383
6384 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6385 G1CollectedHeap* _g1h;
6386
6387 public:
6388 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6389 _g1h(g1h) {}
6390
6391 void do_code_blob(CodeBlob* cb) {
6392 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6393 if (nm == NULL) {
6394 return;
6395 }
6396
6397 if (ScavengeRootsInCode) {
6398 _g1h->register_nmethod(nm);
6399 }
6400 }
6401 };
6402
6403 void G1CollectedHeap::rebuild_strong_code_roots() {
6404 RebuildStrongCodeRootClosure blob_cl(this);
6405 CodeCache::blobs_do(&blob_cl);
6406 }