1 /*
2 * Copyright (c) 2001, 2017, 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 "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullGCScope.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1SerialCollector.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/heapRegion.inline.hpp"
58 #include "gc/g1/heapRegionRemSet.hpp"
59 #include "gc/g1/heapRegionSet.inline.hpp"
60 #include "gc/g1/suspendibleThreadSet.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/gcHeapSummary.hpp"
63 #include "gc/shared/gcId.hpp"
64 #include "gc/shared/gcLocker.inline.hpp"
65 #include "gc/shared/gcTimer.hpp"
66 #include "gc/shared/gcTrace.hpp"
67 #include "gc/shared/gcTraceTime.inline.hpp"
68 #include "gc/shared/generationSpec.hpp"
69 #include "gc/shared/isGCActiveMark.hpp"
70 #include "gc/shared/preservedMarks.inline.hpp"
71 #include "gc/shared/referenceProcessor.inline.hpp"
72 #include "gc/shared/taskqueue.inline.hpp"
73 #include "logging/log.hpp"
74 #include "memory/allocation.hpp"
75 #include "memory/iterator.hpp"
76 #include "memory/resourceArea.hpp"
77 #include "oops/oop.inline.hpp"
78 #include "prims/resolvedMethodTable.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/init.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "utilities/globalDefinitions.hpp"
84 #include "utilities/stack.inline.hpp"
85
86 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
87
88 // INVARIANTS/NOTES
89 //
90 // All allocation activity covered by the G1CollectedHeap interface is
91 // serialized by acquiring the HeapLock. This happens in mem_allocate
92 // and allocate_new_tlab, which are the "entry" points to the
93 // allocation code from the rest of the JVM. (Note that this does not
94 // apply to TLAB allocation, which is not part of this interface: it
95 // is done by clients of this interface.)
96
97 // Local to this file.
98
99 class RefineCardTableEntryClosure: public CardTableEntryClosure {
100 bool _concurrent;
101 public:
102 RefineCardTableEntryClosure() : _concurrent(true) { }
103
104 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
105 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_dirtied;
122 G1CollectedHeap* _g1h;
123 G1SATBCardTableLoggingModRefBS* _g1_bs;
124
125 HeapRegion* region_for_card(jbyte* card_ptr) const {
126 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
127 }
128
129 bool will_become_free(HeapRegion* hr) const {
130 // A region will be freed by free_collection_set if the region is in the
131 // collection set and has not had an evacuation failure.
132 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
133 }
134
135 public:
136 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
137 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
138
139 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
140 HeapRegion* hr = region_for_card(card_ptr);
141
142 // Should only dirty cards in regions that won't be freed.
143 if (!will_become_free(hr)) {
144 *card_ptr = CardTableModRefBS::dirty_card_val();
145 _num_dirtied++;
146 }
147
148 return true;
149 }
150
151 size_t num_dirtied() const { return _num_dirtied; }
152 };
153
154
155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
160 // The from card cache is not the memory that is actually committed. So we cannot
161 // take advantage of the zero_filled parameter.
162 reset_from_card_cache(start_idx, num_regions);
163 }
164
165 // Returns true if the reference points to an object that
166 // can move in an incremental collection.
167 bool G1CollectedHeap::is_scavengable(const void* p) {
168 HeapRegion* hr = heap_region_containing(p);
169 return !hr->is_pinned();
170 }
171
172 // Private methods.
173
174 HeapRegion*
175 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
176 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
177 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
178 if (!_secondary_free_list.is_empty()) {
179 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
180 "secondary_free_list has %u entries",
181 _secondary_free_list.length());
182 // It looks as if there are free regions available on the
183 // secondary_free_list. Let's move them to the free_list and try
184 // again to allocate from it.
185 append_secondary_free_list();
186
187 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
188 "empty we should have moved at least one entry to the free_list");
189 HeapRegion* res = _hrm.allocate_free_region(is_old);
190 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
191 "allocated " HR_FORMAT " from secondary_free_list",
192 HR_FORMAT_PARAMS(res));
193 return res;
194 }
195
196 // Wait here until we get notified either when (a) there are no
197 // more free regions coming or (b) some regions have been moved on
198 // the secondary_free_list.
199 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
200 }
201
202 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
203 "could not allocate from secondary_free_list");
204 return NULL;
205 }
206
207 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
208 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
209 "the only time we use this to allocate a humongous region is "
210 "when we are allocating a single humongous region");
211
212 HeapRegion* res;
213 if (G1StressConcRegionFreeing) {
214 if (!_secondary_free_list.is_empty()) {
215 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
216 "forced to look at the secondary_free_list");
217 res = new_region_try_secondary_free_list(is_old);
218 if (res != NULL) {
219 return res;
220 }
221 }
222 }
223
224 res = _hrm.allocate_free_region(is_old);
225
226 if (res == NULL) {
227 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
228 "res == NULL, trying the secondary_free_list");
229 res = new_region_try_secondary_free_list(is_old);
230 }
231 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
232 // Currently, only attempts to allocate GC alloc regions set
233 // do_expand to true. So, we should only reach here during a
234 // safepoint. If this assumption changes we might have to
235 // reconsider the use of _expand_heap_after_alloc_failure.
236 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
237
238 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
239 word_size * HeapWordSize);
240
241 if (expand(word_size * HeapWordSize)) {
242 // Given that expand() succeeded in expanding the heap, and we
243 // always expand the heap by an amount aligned to the heap
244 // region size, the free list should in theory not be empty.
245 // In either case allocate_free_region() will check for NULL.
246 res = _hrm.allocate_free_region(is_old);
247 } else {
248 _expand_heap_after_alloc_failure = false;
249 }
250 }
251 return res;
252 }
253
254 HeapWord*
255 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
256 uint num_regions,
257 size_t word_size,
258 AllocationContext_t context) {
259 assert(first != G1_NO_HRM_INDEX, "pre-condition");
260 assert(is_humongous(word_size), "word_size should be humongous");
261 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
262
263 // Index of last region in the series.
264 uint last = first + num_regions - 1;
265
266 // We need to initialize the region(s) we just discovered. This is
267 // a bit tricky given that it can happen concurrently with
268 // refinement threads refining cards on these regions and
269 // potentially wanting to refine the BOT as they are scanning
270 // those cards (this can happen shortly after a cleanup; see CR
271 // 6991377). So we have to set up the region(s) carefully and in
272 // a specific order.
273
274 // The word size sum of all the regions we will allocate.
275 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
276 assert(word_size <= word_size_sum, "sanity");
277
278 // This will be the "starts humongous" region.
279 HeapRegion* first_hr = region_at(first);
280 // The header of the new object will be placed at the bottom of
281 // the first region.
282 HeapWord* new_obj = first_hr->bottom();
283 // This will be the new top of the new object.
284 HeapWord* obj_top = new_obj + word_size;
285
286 // First, we need to zero the header of the space that we will be
287 // allocating. When we update top further down, some refinement
288 // threads might try to scan the region. By zeroing the header we
289 // ensure that any thread that will try to scan the region will
290 // come across the zero klass word and bail out.
291 //
292 // NOTE: It would not have been correct to have used
293 // CollectedHeap::fill_with_object() and make the space look like
294 // an int array. The thread that is doing the allocation will
295 // later update the object header to a potentially different array
296 // type and, for a very short period of time, the klass and length
297 // fields will be inconsistent. This could cause a refinement
298 // thread to calculate the object size incorrectly.
299 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
300
301 // Next, pad out the unused tail of the last region with filler
302 // objects, for improved usage accounting.
303 // How many words we use for filler objects.
304 size_t word_fill_size = word_size_sum - word_size;
305
306 // How many words memory we "waste" which cannot hold a filler object.
307 size_t words_not_fillable = 0;
308
309 if (word_fill_size >= min_fill_size()) {
310 fill_with_objects(obj_top, word_fill_size);
311 } else if (word_fill_size > 0) {
312 // We have space to fill, but we cannot fit an object there.
313 words_not_fillable = word_fill_size;
314 word_fill_size = 0;
315 }
316
317 // We will set up the first region as "starts humongous". This
318 // will also update the BOT covering all the regions to reflect
319 // that there is a single object that starts at the bottom of the
320 // first region.
321 first_hr->set_starts_humongous(obj_top, word_fill_size);
322 first_hr->set_allocation_context(context);
323 // Then, if there are any, we will set up the "continues
324 // humongous" regions.
325 HeapRegion* hr = NULL;
326 for (uint i = first + 1; i <= last; ++i) {
327 hr = region_at(i);
328 hr->set_continues_humongous(first_hr);
329 hr->set_allocation_context(context);
330 }
331
332 // Up to this point no concurrent thread would have been able to
333 // do any scanning on any region in this series. All the top
334 // fields still point to bottom, so the intersection between
335 // [bottom,top] and [card_start,card_end] will be empty. Before we
336 // update the top fields, we'll do a storestore to make sure that
337 // no thread sees the update to top before the zeroing of the
338 // object header and the BOT initialization.
339 OrderAccess::storestore();
340
341 // Now, we will update the top fields of the "continues humongous"
342 // regions except the last one.
343 for (uint i = first; i < last; ++i) {
344 hr = region_at(i);
345 hr->set_top(hr->end());
346 }
347
348 hr = region_at(last);
349 // If we cannot fit a filler object, we must set top to the end
350 // of the humongous object, otherwise we cannot iterate the heap
351 // and the BOT will not be complete.
352 hr->set_top(hr->end() - words_not_fillable);
353
354 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
355 "obj_top should be in last region");
356
357 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
358
359 assert(words_not_fillable == 0 ||
360 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
361 "Miscalculation in humongous allocation");
362
363 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
364
365 for (uint i = first; i <= last; ++i) {
366 hr = region_at(i);
367 _humongous_set.add(hr);
368 _hr_printer.alloc(hr);
369 }
370
371 return new_obj;
372 }
373
374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
375 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
376 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
377 }
378
379 // If could fit into free regions w/o expansion, try.
380 // Otherwise, if can expand, do so.
381 // Otherwise, if using ex regions might help, try with ex given back.
382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
383 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
384
385 _verifier->verify_region_sets_optional();
386
387 uint first = G1_NO_HRM_INDEX;
388 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
389
390 if (obj_regions == 1) {
391 // Only one region to allocate, try to use a fast path by directly allocating
392 // from the free lists. Do not try to expand here, we will potentially do that
393 // later.
394 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
395 if (hr != NULL) {
396 first = hr->hrm_index();
397 }
398 } else {
399 // We can't allocate humongous regions spanning more than one region while
400 // cleanupComplete() is running, since some of the regions we find to be
401 // empty might not yet be added to the free list. It is not straightforward
402 // to know in which list they are on so that we can remove them. We only
403 // need to do this if we need to allocate more than one region to satisfy the
404 // current humongous allocation request. If we are only allocating one region
405 // we use the one-region region allocation code (see above), that already
406 // potentially waits for regions from the secondary free list.
407 wait_while_free_regions_coming();
408 append_secondary_free_list_if_not_empty_with_lock();
409
410 // Policy: Try only empty regions (i.e. already committed first). Maybe we
411 // are lucky enough to find some.
412 first = _hrm.find_contiguous_only_empty(obj_regions);
413 if (first != G1_NO_HRM_INDEX) {
414 _hrm.allocate_free_regions_starting_at(first, obj_regions);
415 }
416 }
417
418 if (first == G1_NO_HRM_INDEX) {
419 // Policy: We could not find enough regions for the humongous object in the
420 // free list. Look through the heap to find a mix of free and uncommitted regions.
421 // If so, try expansion.
422 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
423 if (first != G1_NO_HRM_INDEX) {
424 // We found something. Make sure these regions are committed, i.e. expand
425 // the heap. Alternatively we could do a defragmentation GC.
426 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
427 word_size * HeapWordSize);
428
429 _hrm.expand_at(first, obj_regions, workers());
430 g1_policy()->record_new_heap_size(num_regions());
431
432 #ifdef ASSERT
433 for (uint i = first; i < first + obj_regions; ++i) {
434 HeapRegion* hr = region_at(i);
435 assert(hr->is_free(), "sanity");
436 assert(hr->is_empty(), "sanity");
437 assert(is_on_master_free_list(hr), "sanity");
438 }
439 #endif
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 } else {
442 // Policy: Potentially trigger a defragmentation GC.
443 }
444 }
445
446 HeapWord* result = NULL;
447 if (first != G1_NO_HRM_INDEX) {
448 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
449 word_size, context);
450 assert(result != NULL, "it should always return a valid result");
451
452 // A successful humongous object allocation changes the used space
453 // information of the old generation so we need to recalculate the
454 // sizes and update the jstat counters here.
455 g1mm()->update_sizes();
456 }
457
458 _verifier->verify_region_sets_optional();
459
460 return result;
461 }
462
463 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
464 assert_heap_not_locked_and_not_at_safepoint();
465 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
466
467 uint dummy_gc_count_before;
468 uint dummy_gclocker_retry_count = 0;
469 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
470 }
471
472 HeapWord*
473 G1CollectedHeap::mem_allocate(size_t word_size,
474 bool* gc_overhead_limit_was_exceeded) {
475 assert_heap_not_locked_and_not_at_safepoint();
476
477 // Loop until the allocation is satisfied, or unsatisfied after GC.
478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
479 uint gc_count_before;
480
481 HeapWord* result = NULL;
482 if (!is_humongous(word_size)) {
483 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
484 } else {
485 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
486 }
487 if (result != NULL) {
488 return result;
489 }
490
491 // Create the garbage collection operation...
492 VM_G1CollectForAllocation op(gc_count_before, word_size);
493 op.set_allocation_context(AllocationContext::current());
494
495 // ...and get the VM thread to execute it.
496 VMThread::execute(&op);
497
498 if (op.prologue_succeeded() && op.pause_succeeded()) {
499 // If the operation was successful we'll return the result even
500 // if it is NULL. If the allocation attempt failed immediately
501 // after a Full GC, it's unlikely we'll be able to allocate now.
502 HeapWord* result = op.result();
503 if (result != NULL && !is_humongous(word_size)) {
504 // Allocations that take place on VM operations do not do any
505 // card dirtying and we have to do it here. We only have to do
506 // this for non-humongous allocations, though.
507 dirty_young_block(result, word_size);
508 }
509 return result;
510 } else {
511 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
512 return NULL;
513 }
514 assert(op.result() == NULL,
515 "the result should be NULL if the VM op did not succeed");
516 }
517
518 // Give a warning if we seem to be looping forever.
519 if ((QueuedAllocationWarningCount > 0) &&
520 (try_count % QueuedAllocationWarningCount == 0)) {
521 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
522 }
523 }
524
525 ShouldNotReachHere();
526 return NULL;
527 }
528
529 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
530 AllocationContext_t context,
531 uint* gc_count_before_ret,
532 uint* gclocker_retry_count_ret) {
533 // Make sure you read the note in attempt_allocation_humongous().
534
535 assert_heap_not_locked_and_not_at_safepoint();
536 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
537 "be called for humongous allocation requests");
538
539 // We should only get here after the first-level allocation attempt
540 // (attempt_allocation()) failed to allocate.
541
542 // We will loop until a) we manage to successfully perform the
543 // allocation or b) we successfully schedule a collection which
544 // fails to perform the allocation. b) is the only case when we'll
545 // return NULL.
546 HeapWord* result = NULL;
547 for (int try_count = 1; /* we'll return */; try_count += 1) {
548 bool should_try_gc;
549 uint gc_count_before;
550
551 {
552 MutexLockerEx x(Heap_lock);
553 result = _allocator->attempt_allocation_locked(word_size, context);
554 if (result != NULL) {
555 return result;
556 }
557
558 if (GCLocker::is_active_and_needs_gc()) {
559 if (g1_policy()->can_expand_young_list()) {
560 // No need for an ergo verbose message here,
561 // can_expand_young_list() does this when it returns true.
562 result = _allocator->attempt_allocation_force(word_size, context);
563 if (result != NULL) {
564 return result;
565 }
566 }
567 should_try_gc = false;
568 } else {
569 // The GCLocker may not be active but the GCLocker initiated
570 // GC may not yet have been performed (GCLocker::needs_gc()
571 // returns true). In this case we do not try this GC and
572 // wait until the GCLocker initiated GC is performed, and
573 // then retry the allocation.
574 if (GCLocker::needs_gc()) {
575 should_try_gc = false;
576 } else {
577 // Read the GC count while still holding the Heap_lock.
578 gc_count_before = total_collections();
579 should_try_gc = true;
580 }
581 }
582 }
583
584 if (should_try_gc) {
585 bool succeeded;
586 result = do_collection_pause(word_size, gc_count_before, &succeeded,
587 GCCause::_g1_inc_collection_pause);
588 if (result != NULL) {
589 assert(succeeded, "only way to get back a non-NULL result");
590 return result;
591 }
592
593 if (succeeded) {
594 // If we get here we successfully scheduled a collection which
595 // failed to allocate. No point in trying to allocate
596 // further. We'll just return NULL.
597 MutexLockerEx x(Heap_lock);
598 *gc_count_before_ret = total_collections();
599 return NULL;
600 }
601 } else {
602 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
603 MutexLockerEx x(Heap_lock);
604 *gc_count_before_ret = total_collections();
605 return NULL;
606 }
607 // The GCLocker is either active or the GCLocker initiated
608 // GC has not yet been performed. Stall until it is and
609 // then retry the allocation.
610 GCLocker::stall_until_clear();
611 (*gclocker_retry_count_ret) += 1;
612 }
613
614 // We can reach here if we were unsuccessful in scheduling a
615 // collection (because another thread beat us to it) or if we were
616 // stalled due to the GC locker. In either can we should retry the
617 // allocation attempt in case another thread successfully
618 // performed a collection and reclaimed enough space. We do the
619 // first attempt (without holding the Heap_lock) here and the
620 // follow-on attempt will be at the start of the next loop
621 // iteration (after taking the Heap_lock).
622 result = _allocator->attempt_allocation(word_size, context);
623 if (result != NULL) {
624 return result;
625 }
626
627 // Give a warning if we seem to be looping forever.
628 if ((QueuedAllocationWarningCount > 0) &&
629 (try_count % QueuedAllocationWarningCount == 0)) {
630 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
631 "retries %d times", try_count);
632 }
633 }
634
635 ShouldNotReachHere();
636 return NULL;
637 }
638
639 void G1CollectedHeap::begin_archive_alloc_range() {
640 assert_at_safepoint(true /* should_be_vm_thread */);
641 if (_archive_allocator == NULL) {
642 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
643 }
644 }
645
646 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
647 // Allocations in archive regions cannot be of a size that would be considered
648 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
649 // may be different at archive-restore time.
650 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
651 }
652
653 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
654 assert_at_safepoint(true /* should_be_vm_thread */);
655 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
656 if (is_archive_alloc_too_large(word_size)) {
657 return NULL;
658 }
659 return _archive_allocator->archive_mem_allocate(word_size);
660 }
661
662 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
663 size_t end_alignment_in_bytes) {
664 assert_at_safepoint(true /* should_be_vm_thread */);
665 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
666
667 // Call complete_archive to do the real work, filling in the MemRegion
668 // array with the archive regions.
669 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
670 delete _archive_allocator;
671 _archive_allocator = NULL;
672 }
673
674 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
675 assert(ranges != NULL, "MemRegion array NULL");
676 assert(count != 0, "No MemRegions provided");
677 MemRegion reserved = _hrm.reserved();
678 for (size_t i = 0; i < count; i++) {
679 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
680 return false;
681 }
682 }
683 return true;
684 }
685
686 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
687 assert(!is_init_completed(), "Expect to be called at JVM init time");
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690 MutexLockerEx x(Heap_lock);
691
692 MemRegion reserved = _hrm.reserved();
693 HeapWord* prev_last_addr = NULL;
694 HeapRegion* prev_last_region = NULL;
695
696 // Temporarily disable pretouching of heap pages. This interface is used
697 // when mmap'ing archived heap data in, so pre-touching is wasted.
698 FlagSetting fs(AlwaysPreTouch, false);
699
700 // Enable archive object checking used by G1MarkSweep. We have to let it know
701 // about each archive range, so that objects in those ranges aren't marked.
702 G1ArchiveAllocator::enable_archive_object_check();
703
704 // For each specified MemRegion range, allocate the corresponding G1
705 // regions and mark them as archive regions. We expect the ranges in
706 // ascending starting address order, without overlap.
707 for (size_t i = 0; i < count; i++) {
708 MemRegion curr_range = ranges[i];
709 HeapWord* start_address = curr_range.start();
710 size_t word_size = curr_range.word_size();
711 HeapWord* last_address = curr_range.last();
712 size_t commits = 0;
713
714 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
715 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
716 p2i(start_address), p2i(last_address));
717 guarantee(start_address > prev_last_addr,
718 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
719 p2i(start_address), p2i(prev_last_addr));
720 prev_last_addr = last_address;
721
722 // Check for ranges that start in the same G1 region in which the previous
723 // range ended, and adjust the start address so we don't try to allocate
724 // the same region again. If the current range is entirely within that
725 // region, skip it, just adjusting the recorded top.
726 HeapRegion* start_region = _hrm.addr_to_region(start_address);
727 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
728 start_address = start_region->end();
729 if (start_address > last_address) {
730 increase_used(word_size * HeapWordSize);
731 start_region->set_top(last_address + 1);
732 continue;
733 }
734 start_region->set_top(start_address);
735 curr_range = MemRegion(start_address, last_address + 1);
736 start_region = _hrm.addr_to_region(start_address);
737 }
738
739 // Perform the actual region allocation, exiting if it fails.
740 // Then note how much new space we have allocated.
741 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
742 return false;
743 }
744 increase_used(word_size * HeapWordSize);
745 if (commits != 0) {
746 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
747 HeapRegion::GrainWords * HeapWordSize * commits);
748
749 }
750
751 // Mark each G1 region touched by the range as archive, add it to the old set,
752 // and set the allocation context and top.
753 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
754 HeapRegion* last_region = _hrm.addr_to_region(last_address);
755 prev_last_region = last_region;
756
757 while (curr_region != NULL) {
758 assert(curr_region->is_empty() && !curr_region->is_pinned(),
759 "Region already in use (index %u)", curr_region->hrm_index());
760 curr_region->set_allocation_context(AllocationContext::system());
761 curr_region->set_archive();
762 _hr_printer.alloc(curr_region);
763 _old_set.add(curr_region);
764 if (curr_region != last_region) {
765 curr_region->set_top(curr_region->end());
766 curr_region = _hrm.next_region_in_heap(curr_region);
767 } else {
768 curr_region->set_top(last_address + 1);
769 curr_region = NULL;
770 }
771 }
772
773 // Notify mark-sweep of the archive range.
774 G1ArchiveAllocator::set_range_archive(curr_range, true);
775 }
776 return true;
777 }
778
779 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
780 assert(!is_init_completed(), "Expect to be called at JVM init time");
781 assert(ranges != NULL, "MemRegion array NULL");
782 assert(count != 0, "No MemRegions provided");
783 MemRegion reserved = _hrm.reserved();
784 HeapWord *prev_last_addr = NULL;
785 HeapRegion* prev_last_region = NULL;
786
787 // For each MemRegion, create filler objects, if needed, in the G1 regions
788 // that contain the address range. The address range actually within the
789 // MemRegion will not be modified. That is assumed to have been initialized
790 // elsewhere, probably via an mmap of archived heap data.
791 MutexLockerEx x(Heap_lock);
792 for (size_t i = 0; i < count; i++) {
793 HeapWord* start_address = ranges[i].start();
794 HeapWord* last_address = ranges[i].last();
795
796 assert(reserved.contains(start_address) && reserved.contains(last_address),
797 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
798 p2i(start_address), p2i(last_address));
799 assert(start_address > prev_last_addr,
800 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
801 p2i(start_address), p2i(prev_last_addr));
802
803 HeapRegion* start_region = _hrm.addr_to_region(start_address);
804 HeapRegion* last_region = _hrm.addr_to_region(last_address);
805 HeapWord* bottom_address = start_region->bottom();
806
807 // Check for a range beginning in the same region in which the
808 // previous one ended.
809 if (start_region == prev_last_region) {
810 bottom_address = prev_last_addr + 1;
811 }
812
813 // Verify that the regions were all marked as archive regions by
814 // alloc_archive_regions.
815 HeapRegion* curr_region = start_region;
816 while (curr_region != NULL) {
817 guarantee(curr_region->is_archive(),
818 "Expected archive region at index %u", curr_region->hrm_index());
819 if (curr_region != last_region) {
820 curr_region = _hrm.next_region_in_heap(curr_region);
821 } else {
822 curr_region = NULL;
823 }
824 }
825
826 prev_last_addr = last_address;
827 prev_last_region = last_region;
828
829 // Fill the memory below the allocated range with dummy object(s),
830 // if the region bottom does not match the range start, or if the previous
831 // range ended within the same G1 region, and there is a gap.
832 if (start_address != bottom_address) {
833 size_t fill_size = pointer_delta(start_address, bottom_address);
834 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
835 increase_used(fill_size * HeapWordSize);
836 }
837 }
838 }
839
840 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
841 uint* gc_count_before_ret,
842 uint* gclocker_retry_count_ret) {
843 assert_heap_not_locked_and_not_at_safepoint();
844 assert(!is_humongous(word_size), "attempt_allocation() should not "
845 "be called for humongous allocation requests");
846
847 AllocationContext_t context = AllocationContext::current();
848 HeapWord* result = _allocator->attempt_allocation(word_size, context);
849
850 if (result == NULL) {
851 result = attempt_allocation_slow(word_size,
852 context,
853 gc_count_before_ret,
854 gclocker_retry_count_ret);
855 }
856 assert_heap_not_locked();
857 if (result != NULL) {
858 dirty_young_block(result, word_size);
859 }
860 return result;
861 }
862
863 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
864 assert(!is_init_completed(), "Expect to be called at JVM init time");
865 assert(ranges != NULL, "MemRegion array NULL");
866 assert(count != 0, "No MemRegions provided");
867 MemRegion reserved = _hrm.reserved();
868 HeapWord* prev_last_addr = NULL;
869 HeapRegion* prev_last_region = NULL;
870 size_t size_used = 0;
871 size_t uncommitted_regions = 0;
872
873 // For each Memregion, free the G1 regions that constitute it, and
874 // notify mark-sweep that the range is no longer to be considered 'archive.'
875 MutexLockerEx x(Heap_lock);
876 for (size_t i = 0; i < count; i++) {
877 HeapWord* start_address = ranges[i].start();
878 HeapWord* last_address = ranges[i].last();
879
880 assert(reserved.contains(start_address) && reserved.contains(last_address),
881 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
882 p2i(start_address), p2i(last_address));
883 assert(start_address > prev_last_addr,
884 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
885 p2i(start_address), p2i(prev_last_addr));
886 size_used += ranges[i].byte_size();
887 prev_last_addr = last_address;
888
889 HeapRegion* start_region = _hrm.addr_to_region(start_address);
890 HeapRegion* last_region = _hrm.addr_to_region(last_address);
891
892 // Check for ranges that start in the same G1 region in which the previous
893 // range ended, and adjust the start address so we don't try to free
894 // the same region again. If the current range is entirely within that
895 // region, skip it.
896 if (start_region == prev_last_region) {
897 start_address = start_region->end();
898 if (start_address > last_address) {
899 continue;
900 }
901 start_region = _hrm.addr_to_region(start_address);
902 }
903 prev_last_region = last_region;
904
905 // After verifying that each region was marked as an archive region by
906 // alloc_archive_regions, set it free and empty and uncommit it.
907 HeapRegion* curr_region = start_region;
908 while (curr_region != NULL) {
909 guarantee(curr_region->is_archive(),
910 "Expected archive region at index %u", curr_region->hrm_index());
911 uint curr_index = curr_region->hrm_index();
912 _old_set.remove(curr_region);
913 curr_region->set_free();
914 curr_region->set_top(curr_region->bottom());
915 if (curr_region != last_region) {
916 curr_region = _hrm.next_region_in_heap(curr_region);
917 } else {
918 curr_region = NULL;
919 }
920 _hrm.shrink_at(curr_index, 1);
921 uncommitted_regions++;
922 }
923
924 // Notify mark-sweep that this is no longer an archive range.
925 G1ArchiveAllocator::set_range_archive(ranges[i], false);
926 }
927
928 if (uncommitted_regions != 0) {
929 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
930 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
931 }
932 decrease_used(size_used);
933 }
934
935 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
936 uint* gc_count_before_ret,
937 uint* gclocker_retry_count_ret) {
938 // The structure of this method has a lot of similarities to
939 // attempt_allocation_slow(). The reason these two were not merged
940 // into a single one is that such a method would require several "if
941 // allocation is not humongous do this, otherwise do that"
942 // conditional paths which would obscure its flow. In fact, an early
943 // version of this code did use a unified method which was harder to
944 // follow and, as a result, it had subtle bugs that were hard to
945 // track down. So keeping these two methods separate allows each to
946 // be more readable. It will be good to keep these two in sync as
947 // much as possible.
948
949 assert_heap_not_locked_and_not_at_safepoint();
950 assert(is_humongous(word_size), "attempt_allocation_humongous() "
951 "should only be called for humongous allocations");
952
953 // Humongous objects can exhaust the heap quickly, so we should check if we
954 // need to start a marking cycle at each humongous object allocation. We do
955 // the check before we do the actual allocation. The reason for doing it
956 // before the allocation is that we avoid having to keep track of the newly
957 // allocated memory while we do a GC.
958 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
959 word_size)) {
960 collect(GCCause::_g1_humongous_allocation);
961 }
962
963 // We will loop until a) we manage to successfully perform the
964 // allocation or b) we successfully schedule a collection which
965 // fails to perform the allocation. b) is the only case when we'll
966 // return NULL.
967 HeapWord* result = NULL;
968 for (int try_count = 1; /* we'll return */; try_count += 1) {
969 bool should_try_gc;
970 uint gc_count_before;
971
972 {
973 MutexLockerEx x(Heap_lock);
974
975 // Given that humongous objects are not allocated in young
976 // regions, we'll first try to do the allocation without doing a
977 // collection hoping that there's enough space in the heap.
978 result = humongous_obj_allocate(word_size, AllocationContext::current());
979 if (result != NULL) {
980 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
981 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
982 return result;
983 }
984
985 if (GCLocker::is_active_and_needs_gc()) {
986 should_try_gc = false;
987 } else {
988 // The GCLocker may not be active but the GCLocker initiated
989 // GC may not yet have been performed (GCLocker::needs_gc()
990 // returns true). In this case we do not try this GC and
991 // wait until the GCLocker initiated GC is performed, and
992 // then retry the allocation.
993 if (GCLocker::needs_gc()) {
994 should_try_gc = false;
995 } else {
996 // Read the GC count while still holding the Heap_lock.
997 gc_count_before = total_collections();
998 should_try_gc = true;
999 }
1000 }
1001 }
1002
1003 if (should_try_gc) {
1004 // If we failed to allocate the humongous object, we should try to
1005 // do a collection pause (if we're allowed) in case it reclaims
1006 // enough space for the allocation to succeed after the pause.
1007
1008 bool succeeded;
1009 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1010 GCCause::_g1_humongous_allocation);
1011 if (result != NULL) {
1012 assert(succeeded, "only way to get back a non-NULL result");
1013 return result;
1014 }
1015
1016 if (succeeded) {
1017 // If we get here we successfully scheduled a collection which
1018 // failed to allocate. No point in trying to allocate
1019 // further. We'll just return NULL.
1020 MutexLockerEx x(Heap_lock);
1021 *gc_count_before_ret = total_collections();
1022 return NULL;
1023 }
1024 } else {
1025 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1026 MutexLockerEx x(Heap_lock);
1027 *gc_count_before_ret = total_collections();
1028 return NULL;
1029 }
1030 // The GCLocker is either active or the GCLocker initiated
1031 // GC has not yet been performed. Stall until it is and
1032 // then retry the allocation.
1033 GCLocker::stall_until_clear();
1034 (*gclocker_retry_count_ret) += 1;
1035 }
1036
1037 // We can reach here if we were unsuccessful in scheduling a
1038 // collection (because another thread beat us to it) or if we were
1039 // stalled due to the GC locker. In either can we should retry the
1040 // allocation attempt in case another thread successfully
1041 // performed a collection and reclaimed enough space. Give a
1042 // warning if we seem to be looping forever.
1043
1044 if ((QueuedAllocationWarningCount > 0) &&
1045 (try_count % QueuedAllocationWarningCount == 0)) {
1046 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1047 "retries %d times", try_count);
1048 }
1049 }
1050
1051 ShouldNotReachHere();
1052 return NULL;
1053 }
1054
1055 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1056 AllocationContext_t context,
1057 bool expect_null_mutator_alloc_region) {
1058 assert_at_safepoint(true /* should_be_vm_thread */);
1059 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1060 "the current alloc region was unexpectedly found to be non-NULL");
1061
1062 if (!is_humongous(word_size)) {
1063 return _allocator->attempt_allocation_locked(word_size, context);
1064 } else {
1065 HeapWord* result = humongous_obj_allocate(word_size, context);
1066 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1067 collector_state()->set_initiate_conc_mark_if_possible(true);
1068 }
1069 return result;
1070 }
1071
1072 ShouldNotReachHere();
1073 }
1074
1075 class PostCompactionPrinterClosure: public HeapRegionClosure {
1076 private:
1077 G1HRPrinter* _hr_printer;
1078 public:
1079 bool doHeapRegion(HeapRegion* hr) {
1080 assert(!hr->is_young(), "not expecting to find young regions");
1081 _hr_printer->post_compaction(hr);
1082 return false;
1083 }
1084
1085 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1086 : _hr_printer(hr_printer) { }
1087 };
1088
1089 void G1CollectedHeap::print_hrm_post_compaction() {
1090 if (_hr_printer.is_active()) {
1091 PostCompactionPrinterClosure cl(hr_printer());
1092 heap_region_iterate(&cl);
1093 }
1094
1095 }
1096
1097 void G1CollectedHeap::abort_concurrent_cycle() {
1098 // Note: When we have a more flexible GC logging framework that
1099 // allows us to add optional attributes to a GC log record we
1100 // could consider timing and reporting how long we wait in the
1101 // following two methods.
1102 wait_while_free_regions_coming();
1103 // If we start the compaction before the CM threads finish
1104 // scanning the root regions we might trip them over as we'll
1105 // be moving objects / updating references. So let's wait until
1106 // they are done. By telling them to abort, they should complete
1107 // early.
1108 _cm->root_regions()->abort();
1109 _cm->root_regions()->wait_until_scan_finished();
1110 append_secondary_free_list_if_not_empty_with_lock();
1111
1112 // Disable discovery and empty the discovered lists
1113 // for the CM ref processor.
1114 ref_processor_cm()->disable_discovery();
1115 ref_processor_cm()->abandon_partial_discovery();
1116 ref_processor_cm()->verify_no_references_recorded();
1117
1118 // Abandon current iterations of concurrent marking and concurrent
1119 // refinement, if any are in progress.
1120 concurrent_mark()->abort();
1121 }
1122
1123 void G1CollectedHeap::prepare_heap_for_full_collection() {
1124 // Make sure we'll choose a new allocation region afterwards.
1125 _allocator->release_mutator_alloc_region();
1126 _allocator->abandon_gc_alloc_regions();
1127 g1_rem_set()->cleanupHRRS();
1128
1129 // We may have added regions to the current incremental collection
1130 // set between the last GC or pause and now. We need to clear the
1131 // incremental collection set and then start rebuilding it afresh
1132 // after this full GC.
1133 abandon_collection_set(collection_set());
1134
1135 tear_down_region_sets(false /* free_list_only */);
1136 collector_state()->set_gcs_are_young(true);
1137 }
1138
1139 void G1CollectedHeap::reset_card_cache_and_queue() {
1140 if (_hot_card_cache->use_cache()) {
1141 _hot_card_cache->reset_card_counts();
1142 _hot_card_cache->reset_hot_cache();
1143 }
1144
1145 // Discard all stale remembered set updates.
1146 JavaThread::dirty_card_queue_set().abandon_logs();
1147 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1148 }
1149
1150 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1151 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1152 assert(used() == recalculate_used(), "Should be equal");
1153 _verifier->verify_region_sets_optional();
1154 _verifier->verify_before_gc();
1155 _verifier->check_bitmaps("Full GC Start");
1156 }
1157
1158 void G1CollectedHeap::verify_after_full_collection() {
1159 check_gc_time_stamps();
1160 _hrm.verify_optional();
1161 _verifier->verify_region_sets_optional();
1162 _verifier->verify_after_gc();
1163 // Clear the previous marking bitmap, if needed for bitmap verification.
1164 // Note we cannot do this when we clear the next marking bitmap in
1165 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1166 // objects marked during a full GC against the previous bitmap.
1167 // But we need to clear it before calling check_bitmaps below since
1168 // the full GC has compacted objects and updated TAMS but not updated
1169 // the prev bitmap.
1170 if (G1VerifyBitmaps) {
1171 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1172 _cm->clear_prev_bitmap(workers());
1173 }
1174 _verifier->check_bitmaps("Full GC End");
1175
1176 // At this point there should be no regions in the
1177 // entire heap tagged as young.
1178 assert(check_young_list_empty(), "young list should be empty at this point");
1179
1180 // Note: since we've just done a full GC, concurrent
1181 // marking is no longer active. Therefore we need not
1182 // re-enable reference discovery for the CM ref processor.
1183 // That will be done at the start of the next marking cycle.
1184 // We also know that the STW processor should no longer
1185 // discover any new references.
1186 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1187 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1188 ref_processor_stw()->verify_no_references_recorded();
1189 ref_processor_cm()->verify_no_references_recorded();
1190 }
1191
1192 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1193 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1194 G1HeapTransition heap_transition(this);
1195 g1_policy()->record_full_collection_start();
1196
1197 print_heap_before_gc();
1198 print_heap_regions();
1199
1200 abort_concurrent_cycle();
1201 verify_before_full_collection(scope->is_explicit_gc());
1202
1203 gc_prologue(true);
1204 prepare_heap_for_full_collection();
1205
1206 G1SerialCollector serial(scope, ref_processor_stw());
1207 serial.prepare_collection();
1208 serial.collect();
1209 serial.complete_collection();
1210
1211 assert(num_free_regions() == 0, "we should not have added any free regions");
1212 MemoryService::track_memory_usage();
1213
1214 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1215 ClassLoaderDataGraph::purge();
1216 MetaspaceAux::verify_metrics();
1217
1218 // Prepare heap for normal collections.
1219 rebuild_region_sets(false /* free_list_only */);
1220 reset_card_cache_and_queue();
1221 resize_if_necessary_after_full_collection();
1222
1223 // Rebuild the strong code root lists for each region
1224 rebuild_strong_code_roots();
1225
1226 // Start a new incremental collection set for the next pause
1227 start_new_collection_set();
1228
1229 _allocator->init_mutator_alloc_region();
1230
1231 // Post collection state updates.
1232 MetaspaceGC::compute_new_size();
1233 gc_epilogue(true);
1234 g1_policy()->record_full_collection_end();
1235
1236 // Post collection verification.
1237 verify_after_full_collection();
1238
1239 // Post collection logging.
1240 // We should do this after we potentially resize the heap so
1241 // that all the COMMIT / UNCOMMIT events are generated before
1242 // the compaction events.
1243 print_hrm_post_compaction();
1244 heap_transition.print();
1245 print_heap_after_gc();
1246 print_heap_regions();
1247 #ifdef TRACESPINNING
1248 ParallelTaskTerminator::print_termination_counts();
1249 #endif
1250 }
1251
1252 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1253 bool clear_all_soft_refs) {
1254 assert_at_safepoint(true /* should_be_vm_thread */);
1255
1256 if (GCLocker::check_active_before_gc()) {
1257 // Full GC was not completed.
1258 return false;
1259 }
1260
1261 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1262 collector_policy()->should_clear_all_soft_refs();
1263
1264 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1265 do_full_collection_inner(&scope);
1266
1267 // Full collection was successfully completed.
1268 return true;
1269 }
1270
1271 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1272 // Currently, there is no facility in the do_full_collection(bool) API to notify
1273 // the caller that the collection did not succeed (e.g., because it was locked
1274 // out by the GC locker). So, right now, we'll ignore the return value.
1275 bool dummy = do_full_collection(true, /* explicit_gc */
1276 clear_all_soft_refs);
1277 }
1278
1279 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1280 // Include bytes that will be pre-allocated to support collections, as "used".
1281 const size_t used_after_gc = used();
1282 const size_t capacity_after_gc = capacity();
1283 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1284
1285 // This is enforced in arguments.cpp.
1286 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1287 "otherwise the code below doesn't make sense");
1288
1289 // We don't have floating point command-line arguments
1290 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1291 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1292 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1293 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1294
1295 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1296 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1297
1298 // We have to be careful here as these two calculations can overflow
1299 // 32-bit size_t's.
1300 double used_after_gc_d = (double) used_after_gc;
1301 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1302 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1303
1304 // Let's make sure that they are both under the max heap size, which
1305 // by default will make them fit into a size_t.
1306 double desired_capacity_upper_bound = (double) max_heap_size;
1307 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1308 desired_capacity_upper_bound);
1309 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1310 desired_capacity_upper_bound);
1311
1312 // We can now safely turn them into size_t's.
1313 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1314 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1315
1316 // This assert only makes sense here, before we adjust them
1317 // with respect to the min and max heap size.
1318 assert(minimum_desired_capacity <= maximum_desired_capacity,
1319 "minimum_desired_capacity = " SIZE_FORMAT ", "
1320 "maximum_desired_capacity = " SIZE_FORMAT,
1321 minimum_desired_capacity, maximum_desired_capacity);
1322
1323 // Should not be greater than the heap max size. No need to adjust
1324 // it with respect to the heap min size as it's a lower bound (i.e.,
1325 // we'll try to make the capacity larger than it, not smaller).
1326 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1327 // Should not be less than the heap min size. No need to adjust it
1328 // with respect to the heap max size as it's an upper bound (i.e.,
1329 // we'll try to make the capacity smaller than it, not greater).
1330 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1331
1332 if (capacity_after_gc < minimum_desired_capacity) {
1333 // Don't expand unless it's significant
1334 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1335
1336 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1337 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1338 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1339
1340 expand(expand_bytes, _workers);
1341
1342 // No expansion, now see if we want to shrink
1343 } else if (capacity_after_gc > maximum_desired_capacity) {
1344 // Capacity too large, compute shrinking size
1345 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1346
1347 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1348 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1349 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1350
1351 shrink(shrink_bytes);
1352 }
1353 }
1354
1355 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1356 AllocationContext_t context,
1357 bool do_gc,
1358 bool clear_all_soft_refs,
1359 bool expect_null_mutator_alloc_region,
1360 bool* gc_succeeded) {
1361 *gc_succeeded = true;
1362 // Let's attempt the allocation first.
1363 HeapWord* result =
1364 attempt_allocation_at_safepoint(word_size,
1365 context,
1366 expect_null_mutator_alloc_region);
1367 if (result != NULL) {
1368 assert(*gc_succeeded, "sanity");
1369 return result;
1370 }
1371
1372 // In a G1 heap, we're supposed to keep allocation from failing by
1373 // incremental pauses. Therefore, at least for now, we'll favor
1374 // expansion over collection. (This might change in the future if we can
1375 // do something smarter than full collection to satisfy a failed alloc.)
1376 result = expand_and_allocate(word_size, context);
1377 if (result != NULL) {
1378 assert(*gc_succeeded, "sanity");
1379 return result;
1380 }
1381
1382 if (do_gc) {
1383 // Expansion didn't work, we'll try to do a Full GC.
1384 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1385 clear_all_soft_refs);
1386 }
1387
1388 return NULL;
1389 }
1390
1391 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1392 AllocationContext_t context,
1393 bool* succeeded) {
1394 assert_at_safepoint(true /* should_be_vm_thread */);
1395
1396 // Attempts to allocate followed by Full GC.
1397 HeapWord* result =
1398 satisfy_failed_allocation_helper(word_size,
1399 context,
1400 true, /* do_gc */
1401 false, /* clear_all_soft_refs */
1402 false, /* expect_null_mutator_alloc_region */
1403 succeeded);
1404
1405 if (result != NULL || !*succeeded) {
1406 return result;
1407 }
1408
1409 // Attempts to allocate followed by Full GC that will collect all soft references.
1410 result = satisfy_failed_allocation_helper(word_size,
1411 context,
1412 true, /* do_gc */
1413 true, /* clear_all_soft_refs */
1414 true, /* expect_null_mutator_alloc_region */
1415 succeeded);
1416
1417 if (result != NULL || !*succeeded) {
1418 return result;
1419 }
1420
1421 // Attempts to allocate, no GC
1422 result = satisfy_failed_allocation_helper(word_size,
1423 context,
1424 false, /* do_gc */
1425 false, /* clear_all_soft_refs */
1426 true, /* expect_null_mutator_alloc_region */
1427 succeeded);
1428
1429 if (result != NULL) {
1430 assert(*succeeded, "sanity");
1431 return result;
1432 }
1433
1434 assert(!collector_policy()->should_clear_all_soft_refs(),
1435 "Flag should have been handled and cleared prior to this point");
1436
1437 // What else? We might try synchronous finalization later. If the total
1438 // space available is large enough for the allocation, then a more
1439 // complete compaction phase than we've tried so far might be
1440 // appropriate.
1441 assert(*succeeded, "sanity");
1442 return NULL;
1443 }
1444
1445 // Attempting to expand the heap sufficiently
1446 // to support an allocation of the given "word_size". If
1447 // successful, perform the allocation and return the address of the
1448 // allocated block, or else "NULL".
1449
1450 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1451 assert_at_safepoint(true /* should_be_vm_thread */);
1452
1453 _verifier->verify_region_sets_optional();
1454
1455 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1456 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1457 word_size * HeapWordSize);
1458
1459
1460 if (expand(expand_bytes, _workers)) {
1461 _hrm.verify_optional();
1462 _verifier->verify_region_sets_optional();
1463 return attempt_allocation_at_safepoint(word_size,
1464 context,
1465 false /* expect_null_mutator_alloc_region */);
1466 }
1467 return NULL;
1468 }
1469
1470 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1471 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1472 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1473 HeapRegion::GrainBytes);
1474
1475 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1476 expand_bytes, aligned_expand_bytes);
1477
1478 if (is_maximal_no_gc()) {
1479 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1480 return false;
1481 }
1482
1483 double expand_heap_start_time_sec = os::elapsedTime();
1484 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1485 assert(regions_to_expand > 0, "Must expand by at least one region");
1486
1487 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1488 if (expand_time_ms != NULL) {
1489 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1490 }
1491
1492 if (expanded_by > 0) {
1493 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1494 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1495 g1_policy()->record_new_heap_size(num_regions());
1496 } else {
1497 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1498
1499 // The expansion of the virtual storage space was unsuccessful.
1500 // Let's see if it was because we ran out of swap.
1501 if (G1ExitOnExpansionFailure &&
1502 _hrm.available() >= regions_to_expand) {
1503 // We had head room...
1504 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1505 }
1506 }
1507 return regions_to_expand > 0;
1508 }
1509
1510 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1511 size_t aligned_shrink_bytes =
1512 ReservedSpace::page_align_size_down(shrink_bytes);
1513 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1514 HeapRegion::GrainBytes);
1515 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1516
1517 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1518 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1519
1520
1521 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1522 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1523 if (num_regions_removed > 0) {
1524 g1_policy()->record_new_heap_size(num_regions());
1525 } else {
1526 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1527 }
1528 }
1529
1530 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1531 _verifier->verify_region_sets_optional();
1532
1533 // We should only reach here at the end of a Full GC which means we
1534 // should not not be holding to any GC alloc regions. The method
1535 // below will make sure of that and do any remaining clean up.
1536 _allocator->abandon_gc_alloc_regions();
1537
1538 // Instead of tearing down / rebuilding the free lists here, we
1539 // could instead use the remove_all_pending() method on free_list to
1540 // remove only the ones that we need to remove.
1541 tear_down_region_sets(true /* free_list_only */);
1542 shrink_helper(shrink_bytes);
1543 rebuild_region_sets(true /* free_list_only */);
1544
1545 _hrm.verify_optional();
1546 _verifier->verify_region_sets_optional();
1547 }
1548
1549 // Public methods.
1550
1551 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1552 CollectedHeap(),
1553 _collector_policy(collector_policy),
1554 _g1_policy(create_g1_policy()),
1555 _collection_set(this, _g1_policy),
1556 _dirty_card_queue_set(false),
1557 _is_alive_closure_cm(this),
1558 _is_alive_closure_stw(this),
1559 _ref_processor_cm(NULL),
1560 _ref_processor_stw(NULL),
1561 _bot(NULL),
1562 _hot_card_cache(NULL),
1563 _g1_rem_set(NULL),
1564 _cg1r(NULL),
1565 _g1mm(NULL),
1566 _refine_cte_cl(NULL),
1567 _preserved_marks_set(true /* in_c_heap */),
1568 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1569 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1570 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1571 _humongous_reclaim_candidates(),
1572 _has_humongous_reclaim_candidates(false),
1573 _archive_allocator(NULL),
1574 _free_regions_coming(false),
1575 _gc_time_stamp(0),
1576 _summary_bytes_used(0),
1577 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1578 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1579 _expand_heap_after_alloc_failure(true),
1580 _old_marking_cycles_started(0),
1581 _old_marking_cycles_completed(0),
1582 _in_cset_fast_test(),
1583 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1584 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1585
1586 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1587 /* are_GC_task_threads */true,
1588 /* are_ConcurrentGC_threads */false);
1589 _workers->initialize_workers();
1590 _verifier = new G1HeapVerifier(this);
1591
1592 _allocator = G1Allocator::create_allocator(this);
1593
1594 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1595
1596 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1597
1598 // Override the default _filler_array_max_size so that no humongous filler
1599 // objects are created.
1600 _filler_array_max_size = _humongous_object_threshold_in_words;
1601
1602 uint n_queues = ParallelGCThreads;
1603 _task_queues = new RefToScanQueueSet(n_queues);
1604
1605 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1606
1607 for (uint i = 0; i < n_queues; i++) {
1608 RefToScanQueue* q = new RefToScanQueue();
1609 q->initialize();
1610 _task_queues->register_queue(i, q);
1611 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1612 }
1613
1614 // Initialize the G1EvacuationFailureALot counters and flags.
1615 NOT_PRODUCT(reset_evacuation_should_fail();)
1616
1617 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1618 }
1619
1620 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1621 size_t size,
1622 size_t translation_factor) {
1623 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1624 // Allocate a new reserved space, preferring to use large pages.
1625 ReservedSpace rs(size, preferred_page_size);
1626 G1RegionToSpaceMapper* result =
1627 G1RegionToSpaceMapper::create_mapper(rs,
1628 size,
1629 rs.alignment(),
1630 HeapRegion::GrainBytes,
1631 translation_factor,
1632 mtGC);
1633
1634 os::trace_page_sizes_for_requested_size(description,
1635 size,
1636 preferred_page_size,
1637 rs.alignment(),
1638 rs.base(),
1639 rs.size());
1640
1641 return result;
1642 }
1643
1644 jint G1CollectedHeap::initialize() {
1645 CollectedHeap::pre_initialize();
1646 os::enable_vtime();
1647
1648 // Necessary to satisfy locking discipline assertions.
1649
1650 MutexLocker x(Heap_lock);
1651
1652 // While there are no constraints in the GC code that HeapWordSize
1653 // be any particular value, there are multiple other areas in the
1654 // system which believe this to be true (e.g. oop->object_size in some
1655 // cases incorrectly returns the size in wordSize units rather than
1656 // HeapWordSize).
1657 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1658
1659 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1660 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1661 size_t heap_alignment = collector_policy()->heap_alignment();
1662
1663 // Ensure that the sizes are properly aligned.
1664 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1665 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1666 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1667
1668 _refine_cte_cl = new RefineCardTableEntryClosure();
1669
1670 jint ecode = JNI_OK;
1671 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1672 if (_cg1r == NULL) {
1673 return ecode;
1674 }
1675
1676 // Reserve the maximum.
1677
1678 // When compressed oops are enabled, the preferred heap base
1679 // is calculated by subtracting the requested size from the
1680 // 32Gb boundary and using the result as the base address for
1681 // heap reservation. If the requested size is not aligned to
1682 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1683 // into the ReservedHeapSpace constructor) then the actual
1684 // base of the reserved heap may end up differing from the
1685 // address that was requested (i.e. the preferred heap base).
1686 // If this happens then we could end up using a non-optimal
1687 // compressed oops mode.
1688
1689 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1690 heap_alignment);
1691
1692 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1693
1694 // Create the barrier set for the entire reserved region.
1695 G1SATBCardTableLoggingModRefBS* bs
1696 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1697 bs->initialize();
1698 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1699 set_barrier_set(bs);
1700
1701 // Create the hot card cache.
1702 _hot_card_cache = new G1HotCardCache(this);
1703
1704 // Also create a G1 rem set.
1705 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1706
1707 // Carve out the G1 part of the heap.
1708 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1709 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1710 G1RegionToSpaceMapper* heap_storage =
1711 G1RegionToSpaceMapper::create_mapper(g1_rs,
1712 g1_rs.size(),
1713 page_size,
1714 HeapRegion::GrainBytes,
1715 1,
1716 mtJavaHeap);
1717 os::trace_page_sizes("Heap",
1718 collector_policy()->min_heap_byte_size(),
1719 max_byte_size,
1720 page_size,
1721 heap_rs.base(),
1722 heap_rs.size());
1723 heap_storage->set_mapping_changed_listener(&_listener);
1724
1725 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1726 G1RegionToSpaceMapper* bot_storage =
1727 create_aux_memory_mapper("Block Offset Table",
1728 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1729 G1BlockOffsetTable::heap_map_factor());
1730
1731 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1732 G1RegionToSpaceMapper* cardtable_storage =
1733 create_aux_memory_mapper("Card Table",
1734 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1735 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1736
1737 G1RegionToSpaceMapper* card_counts_storage =
1738 create_aux_memory_mapper("Card Counts Table",
1739 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1740 G1CardCounts::heap_map_factor());
1741
1742 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1743 G1RegionToSpaceMapper* prev_bitmap_storage =
1744 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1745 G1RegionToSpaceMapper* next_bitmap_storage =
1746 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1747
1748 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1749 g1_barrier_set()->initialize(cardtable_storage);
1750 // Do later initialization work for concurrent refinement.
1751 _hot_card_cache->initialize(card_counts_storage);
1752
1753 // 6843694 - ensure that the maximum region index can fit
1754 // in the remembered set structures.
1755 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1756 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1757
1758 g1_rem_set()->initialize(max_capacity(), max_regions());
1759
1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1763 "too many cards per region");
1764
1765 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1766
1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1768
1769 {
1770 HeapWord* start = _hrm.reserved().start();
1771 HeapWord* end = _hrm.reserved().end();
1772 size_t granularity = HeapRegion::GrainBytes;
1773
1774 _in_cset_fast_test.initialize(start, end, granularity);
1775 _humongous_reclaim_candidates.initialize(start, end, granularity);
1776 }
1777
1778 // Create the G1ConcurrentMark data structure and thread.
1779 // (Must do this late, so that "max_regions" is defined.)
1780 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1781 if (_cm == NULL || !_cm->completed_initialization()) {
1782 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1783 return JNI_ENOMEM;
1784 }
1785 _cmThread = _cm->cmThread();
1786
1787 // Now expand into the initial heap size.
1788 if (!expand(init_byte_size, _workers)) {
1789 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1790 return JNI_ENOMEM;
1791 }
1792
1793 // Perform any initialization actions delegated to the policy.
1794 g1_policy()->init(this, &_collection_set);
1795
1796 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1797 SATB_Q_FL_lock,
1798 G1SATBProcessCompletedThreshold,
1799 Shared_SATB_Q_lock);
1800
1801 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1802 DirtyCardQ_CBL_mon,
1803 DirtyCardQ_FL_lock,
1804 (int)concurrent_g1_refine()->yellow_zone(),
1805 (int)concurrent_g1_refine()->red_zone(),
1806 Shared_DirtyCardQ_lock,
1807 NULL, // fl_owner
1808 true); // init_free_ids
1809
1810 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1811 DirtyCardQ_CBL_mon,
1812 DirtyCardQ_FL_lock,
1813 -1, // never trigger processing
1814 -1, // no limit on length
1815 Shared_DirtyCardQ_lock,
1816 &JavaThread::dirty_card_queue_set());
1817
1818 // Here we allocate the dummy HeapRegion that is required by the
1819 // G1AllocRegion class.
1820 HeapRegion* dummy_region = _hrm.get_dummy_region();
1821
1822 // We'll re-use the same region whether the alloc region will
1823 // require BOT updates or not and, if it doesn't, then a non-young
1824 // region will complain that it cannot support allocations without
1825 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1826 dummy_region->set_eden();
1827 // Make sure it's full.
1828 dummy_region->set_top(dummy_region->end());
1829 G1AllocRegion::setup(this, dummy_region);
1830
1831 _allocator->init_mutator_alloc_region();
1832
1833 // Do create of the monitoring and management support so that
1834 // values in the heap have been properly initialized.
1835 _g1mm = new G1MonitoringSupport(this);
1836
1837 G1StringDedup::initialize();
1838
1839 _preserved_marks_set.init(ParallelGCThreads);
1840
1841 _collection_set.initialize(max_regions());
1842
1843 return JNI_OK;
1844 }
1845
1846 void G1CollectedHeap::stop() {
1847 // Stop all concurrent threads. We do this to make sure these threads
1848 // do not continue to execute and access resources (e.g. logging)
1849 // that are destroyed during shutdown.
1850 _cg1r->stop();
1851 _cmThread->stop();
1852 if (G1StringDedup::is_enabled()) {
1853 G1StringDedup::stop();
1854 }
1855 }
1856
1857 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1858 return HeapRegion::max_region_size();
1859 }
1860
1861 void G1CollectedHeap::post_initialize() {
1862 ref_processing_init();
1863 }
1864
1865 void G1CollectedHeap::ref_processing_init() {
1866 // Reference processing in G1 currently works as follows:
1867 //
1868 // * There are two reference processor instances. One is
1869 // used to record and process discovered references
1870 // during concurrent marking; the other is used to
1871 // record and process references during STW pauses
1872 // (both full and incremental).
1873 // * Both ref processors need to 'span' the entire heap as
1874 // the regions in the collection set may be dotted around.
1875 //
1876 // * For the concurrent marking ref processor:
1877 // * Reference discovery is enabled at initial marking.
1878 // * Reference discovery is disabled and the discovered
1879 // references processed etc during remarking.
1880 // * Reference discovery is MT (see below).
1881 // * Reference discovery requires a barrier (see below).
1882 // * Reference processing may or may not be MT
1883 // (depending on the value of ParallelRefProcEnabled
1884 // and ParallelGCThreads).
1885 // * A full GC disables reference discovery by the CM
1886 // ref processor and abandons any entries on it's
1887 // discovered lists.
1888 //
1889 // * For the STW processor:
1890 // * Non MT discovery is enabled at the start of a full GC.
1891 // * Processing and enqueueing during a full GC is non-MT.
1892 // * During a full GC, references are processed after marking.
1893 //
1894 // * Discovery (may or may not be MT) is enabled at the start
1895 // of an incremental evacuation pause.
1896 // * References are processed near the end of a STW evacuation pause.
1897 // * For both types of GC:
1898 // * Discovery is atomic - i.e. not concurrent.
1899 // * Reference discovery will not need a barrier.
1900
1901 MemRegion mr = reserved_region();
1902
1903 // Concurrent Mark ref processor
1904 _ref_processor_cm =
1905 new ReferenceProcessor(mr, // span
1906 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1907 // mt processing
1908 ParallelGCThreads,
1909 // degree of mt processing
1910 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1911 // mt discovery
1912 MAX2(ParallelGCThreads, ConcGCThreads),
1913 // degree of mt discovery
1914 false,
1915 // Reference discovery is not atomic
1916 &_is_alive_closure_cm);
1917 // is alive closure
1918 // (for efficiency/performance)
1919
1920 // STW ref processor
1921 _ref_processor_stw =
1922 new ReferenceProcessor(mr, // span
1923 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1924 // mt processing
1925 ParallelGCThreads,
1926 // degree of mt processing
1927 (ParallelGCThreads > 1),
1928 // mt discovery
1929 ParallelGCThreads,
1930 // degree of mt discovery
1931 true,
1932 // Reference discovery is atomic
1933 &_is_alive_closure_stw);
1934 // is alive closure
1935 // (for efficiency/performance)
1936 }
1937
1938 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1939 return _collector_policy;
1940 }
1941
1942 size_t G1CollectedHeap::capacity() const {
1943 return _hrm.length() * HeapRegion::GrainBytes;
1944 }
1945
1946 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1947 hr->reset_gc_time_stamp();
1948 }
1949
1950 #ifndef PRODUCT
1951
1952 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1953 private:
1954 unsigned _gc_time_stamp;
1955 bool _failures;
1956
1957 public:
1958 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1959 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1960
1961 virtual bool doHeapRegion(HeapRegion* hr) {
1962 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1963 if (_gc_time_stamp != region_gc_time_stamp) {
1964 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1965 region_gc_time_stamp, _gc_time_stamp);
1966 _failures = true;
1967 }
1968 return false;
1969 }
1970
1971 bool failures() { return _failures; }
1972 };
1973
1974 void G1CollectedHeap::check_gc_time_stamps() {
1975 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1976 heap_region_iterate(&cl);
1977 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1978 }
1979 #endif // PRODUCT
1980
1981 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1982 _hot_card_cache->drain(cl, worker_i);
1983 }
1984
1985 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1986 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1987 size_t n_completed_buffers = 0;
1988 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
1989 n_completed_buffers++;
1990 }
1991 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1992 dcqs.clear_n_completed_buffers();
1993 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1994 }
1995
1996 // Computes the sum of the storage used by the various regions.
1997 size_t G1CollectedHeap::used() const {
1998 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1999 if (_archive_allocator != NULL) {
2000 result += _archive_allocator->used();
2001 }
2002 return result;
2003 }
2004
2005 size_t G1CollectedHeap::used_unlocked() const {
2006 return _summary_bytes_used;
2007 }
2008
2009 class SumUsedClosure: public HeapRegionClosure {
2010 size_t _used;
2011 public:
2012 SumUsedClosure() : _used(0) {}
2013 bool doHeapRegion(HeapRegion* r) {
2014 _used += r->used();
2015 return false;
2016 }
2017 size_t result() { return _used; }
2018 };
2019
2020 size_t G1CollectedHeap::recalculate_used() const {
2021 double recalculate_used_start = os::elapsedTime();
2022
2023 SumUsedClosure blk;
2024 heap_region_iterate(&blk);
2025
2026 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2027 return blk.result();
2028 }
2029
2030 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2031 switch (cause) {
2032 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2033 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2034 case GCCause::_update_allocation_context_stats_inc: return true;
2035 case GCCause::_wb_conc_mark: return true;
2036 default : return false;
2037 }
2038 }
2039
2040 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2041 switch (cause) {
2042 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2043 case GCCause::_g1_humongous_allocation: return true;
2044 default: return is_user_requested_concurrent_full_gc(cause);
2045 }
2046 }
2047
2048 #ifndef PRODUCT
2049 void G1CollectedHeap::allocate_dummy_regions() {
2050 // Let's fill up most of the region
2051 size_t word_size = HeapRegion::GrainWords - 1024;
2052 // And as a result the region we'll allocate will be humongous.
2053 guarantee(is_humongous(word_size), "sanity");
2054
2055 // _filler_array_max_size is set to humongous object threshold
2056 // but temporarily change it to use CollectedHeap::fill_with_object().
2057 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2058
2059 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2060 // Let's use the existing mechanism for the allocation
2061 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2062 AllocationContext::system());
2063 if (dummy_obj != NULL) {
2064 MemRegion mr(dummy_obj, word_size);
2065 CollectedHeap::fill_with_object(mr);
2066 } else {
2067 // If we can't allocate once, we probably cannot allocate
2068 // again. Let's get out of the loop.
2069 break;
2070 }
2071 }
2072 }
2073 #endif // !PRODUCT
2074
2075 void G1CollectedHeap::increment_old_marking_cycles_started() {
2076 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2077 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2078 "Wrong marking cycle count (started: %d, completed: %d)",
2079 _old_marking_cycles_started, _old_marking_cycles_completed);
2080
2081 _old_marking_cycles_started++;
2082 }
2083
2084 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2085 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2086
2087 // We assume that if concurrent == true, then the caller is a
2088 // concurrent thread that was joined the Suspendible Thread
2089 // Set. If there's ever a cheap way to check this, we should add an
2090 // assert here.
2091
2092 // Given that this method is called at the end of a Full GC or of a
2093 // concurrent cycle, and those can be nested (i.e., a Full GC can
2094 // interrupt a concurrent cycle), the number of full collections
2095 // completed should be either one (in the case where there was no
2096 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2097 // behind the number of full collections started.
2098
2099 // This is the case for the inner caller, i.e. a Full GC.
2100 assert(concurrent ||
2101 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2102 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2103 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2104 "is inconsistent with _old_marking_cycles_completed = %u",
2105 _old_marking_cycles_started, _old_marking_cycles_completed);
2106
2107 // This is the case for the outer caller, i.e. the concurrent cycle.
2108 assert(!concurrent ||
2109 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2110 "for outer caller (concurrent cycle): "
2111 "_old_marking_cycles_started = %u "
2112 "is inconsistent with _old_marking_cycles_completed = %u",
2113 _old_marking_cycles_started, _old_marking_cycles_completed);
2114
2115 _old_marking_cycles_completed += 1;
2116
2117 // We need to clear the "in_progress" flag in the CM thread before
2118 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2119 // is set) so that if a waiter requests another System.gc() it doesn't
2120 // incorrectly see that a marking cycle is still in progress.
2121 if (concurrent) {
2122 _cmThread->set_idle();
2123 }
2124
2125 // This notify_all() will ensure that a thread that called
2126 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2127 // and it's waiting for a full GC to finish will be woken up. It is
2128 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2129 FullGCCount_lock->notify_all();
2130 }
2131
2132 void G1CollectedHeap::collect(GCCause::Cause cause) {
2133 assert_heap_not_locked();
2134
2135 uint gc_count_before;
2136 uint old_marking_count_before;
2137 uint full_gc_count_before;
2138 bool retry_gc;
2139
2140 do {
2141 retry_gc = false;
2142
2143 {
2144 MutexLocker ml(Heap_lock);
2145
2146 // Read the GC count while holding the Heap_lock
2147 gc_count_before = total_collections();
2148 full_gc_count_before = total_full_collections();
2149 old_marking_count_before = _old_marking_cycles_started;
2150 }
2151
2152 if (should_do_concurrent_full_gc(cause)) {
2153 // Schedule an initial-mark evacuation pause that will start a
2154 // concurrent cycle. We're setting word_size to 0 which means that
2155 // we are not requesting a post-GC allocation.
2156 VM_G1IncCollectionPause op(gc_count_before,
2157 0, /* word_size */
2158 true, /* should_initiate_conc_mark */
2159 g1_policy()->max_pause_time_ms(),
2160 cause);
2161 op.set_allocation_context(AllocationContext::current());
2162
2163 VMThread::execute(&op);
2164 if (!op.pause_succeeded()) {
2165 if (old_marking_count_before == _old_marking_cycles_started) {
2166 retry_gc = op.should_retry_gc();
2167 } else {
2168 // A Full GC happened while we were trying to schedule the
2169 // initial-mark GC. No point in starting a new cycle given
2170 // that the whole heap was collected anyway.
2171 }
2172
2173 if (retry_gc) {
2174 if (GCLocker::is_active_and_needs_gc()) {
2175 GCLocker::stall_until_clear();
2176 }
2177 }
2178 }
2179 } else {
2180 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2181 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2182
2183 // Schedule a standard evacuation pause. We're setting word_size
2184 // to 0 which means that we are not requesting a post-GC allocation.
2185 VM_G1IncCollectionPause op(gc_count_before,
2186 0, /* word_size */
2187 false, /* should_initiate_conc_mark */
2188 g1_policy()->max_pause_time_ms(),
2189 cause);
2190 VMThread::execute(&op);
2191 } else {
2192 // Schedule a Full GC.
2193 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2194 VMThread::execute(&op);
2195 }
2196 }
2197 } while (retry_gc);
2198 }
2199
2200 bool G1CollectedHeap::is_in(const void* p) const {
2201 if (_hrm.reserved().contains(p)) {
2202 // Given that we know that p is in the reserved space,
2203 // heap_region_containing() should successfully
2204 // return the containing region.
2205 HeapRegion* hr = heap_region_containing(p);
2206 return hr->is_in(p);
2207 } else {
2208 return false;
2209 }
2210 }
2211
2212 #ifdef ASSERT
2213 bool G1CollectedHeap::is_in_exact(const void* p) const {
2214 bool contains = reserved_region().contains(p);
2215 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2216 if (contains && available) {
2217 return true;
2218 } else {
2219 return false;
2220 }
2221 }
2222 #endif
2223
2224 // Iteration functions.
2225
2226 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2227
2228 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2229 ExtendedOopClosure* _cl;
2230 public:
2231 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2232 bool doHeapRegion(HeapRegion* r) {
2233 if (!r->is_continues_humongous()) {
2234 r->oop_iterate(_cl);
2235 }
2236 return false;
2237 }
2238 };
2239
2240 // Iterates an ObjectClosure over all objects within a HeapRegion.
2241
2242 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2243 ObjectClosure* _cl;
2244 public:
2245 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2246 bool doHeapRegion(HeapRegion* r) {
2247 if (!r->is_continues_humongous()) {
2248 r->object_iterate(_cl);
2249 }
2250 return false;
2251 }
2252 };
2253
2254 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2255 IterateObjectClosureRegionClosure blk(cl);
2256 heap_region_iterate(&blk);
2257 }
2258
2259 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2260 _hrm.iterate(cl);
2261 }
2262
2263 void
2264 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2265 uint worker_id,
2266 HeapRegionClaimer *hrclaimer,
2267 bool concurrent) const {
2268 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2269 }
2270
2271 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2272 _collection_set.iterate(cl);
2273 }
2274
2275 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2276 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2277 }
2278
2279 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2280 HeapRegion* result = _hrm.next_region_in_heap(from);
2281 while (result != NULL && result->is_pinned()) {
2282 result = _hrm.next_region_in_heap(result);
2283 }
2284 return result;
2285 }
2286
2287 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2288 HeapRegion* hr = heap_region_containing(addr);
2289 return hr->block_start(addr);
2290 }
2291
2292 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2293 HeapRegion* hr = heap_region_containing(addr);
2294 return hr->block_size(addr);
2295 }
2296
2297 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2298 HeapRegion* hr = heap_region_containing(addr);
2299 return hr->block_is_obj(addr);
2300 }
2301
2302 bool G1CollectedHeap::supports_tlab_allocation() const {
2303 return true;
2304 }
2305
2306 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2307 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2308 }
2309
2310 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2311 return _eden.length() * HeapRegion::GrainBytes;
2312 }
2313
2314 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2315 // must be equal to the humongous object limit.
2316 size_t G1CollectedHeap::max_tlab_size() const {
2317 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2318 }
2319
2320 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2321 AllocationContext_t context = AllocationContext::current();
2322 return _allocator->unsafe_max_tlab_alloc(context);
2323 }
2324
2325 size_t G1CollectedHeap::max_capacity() const {
2326 return _hrm.reserved().byte_size();
2327 }
2328
2329 jlong G1CollectedHeap::millis_since_last_gc() {
2330 // See the notes in GenCollectedHeap::millis_since_last_gc()
2331 // for more information about the implementation.
2332 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2333 _g1_policy->collection_pause_end_millis();
2334 if (ret_val < 0) {
2335 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2336 ". returning zero instead.", ret_val);
2337 return 0;
2338 }
2339 return ret_val;
2340 }
2341
2342 void G1CollectedHeap::prepare_for_verify() {
2343 _verifier->prepare_for_verify();
2344 }
2345
2346 void G1CollectedHeap::verify(VerifyOption vo) {
2347 _verifier->verify(vo);
2348 }
2349
2350 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2351 return true;
2352 }
2353
2354 const char* const* G1CollectedHeap::concurrent_phases() const {
2355 return _cmThread->concurrent_phases();
2356 }
2357
2358 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2359 return _cmThread->request_concurrent_phase(phase);
2360 }
2361
2362 class PrintRegionClosure: public HeapRegionClosure {
2363 outputStream* _st;
2364 public:
2365 PrintRegionClosure(outputStream* st) : _st(st) {}
2366 bool doHeapRegion(HeapRegion* r) {
2367 r->print_on(_st);
2368 return false;
2369 }
2370 };
2371
2372 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2373 const HeapRegion* hr,
2374 const VerifyOption vo) const {
2375 switch (vo) {
2376 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2377 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2378 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2379 default: ShouldNotReachHere();
2380 }
2381 return false; // keep some compilers happy
2382 }
2383
2384 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2385 const VerifyOption vo) const {
2386 switch (vo) {
2387 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2388 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2389 case VerifyOption_G1UseMarkWord: {
2390 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2391 return !obj->is_gc_marked() && !hr->is_archive();
2392 }
2393 default: ShouldNotReachHere();
2394 }
2395 return false; // keep some compilers happy
2396 }
2397
2398 void G1CollectedHeap::print_heap_regions() const {
2399 Log(gc, heap, region) log;
2400 if (log.is_trace()) {
2401 ResourceMark rm;
2402 print_regions_on(log.trace_stream());
2403 }
2404 }
2405
2406 void G1CollectedHeap::print_on(outputStream* st) const {
2407 st->print(" %-20s", "garbage-first heap");
2408 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2409 capacity()/K, used_unlocked()/K);
2410 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2411 p2i(_hrm.reserved().start()),
2412 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2413 p2i(_hrm.reserved().end()));
2414 st->cr();
2415 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2416 uint young_regions = young_regions_count();
2417 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2418 (size_t) young_regions * HeapRegion::GrainBytes / K);
2419 uint survivor_regions = survivor_regions_count();
2420 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2421 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2422 st->cr();
2423 MetaspaceAux::print_on(st);
2424 }
2425
2426 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2427 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2428 "HS=humongous(starts), HC=humongous(continues), "
2429 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2430 "AC=allocation context, "
2431 "TAMS=top-at-mark-start (previous, next)");
2432 PrintRegionClosure blk(st);
2433 heap_region_iterate(&blk);
2434 }
2435
2436 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2437 print_on(st);
2438
2439 // Print the per-region information.
2440 print_regions_on(st);
2441 }
2442
2443 void G1CollectedHeap::print_on_error(outputStream* st) const {
2444 this->CollectedHeap::print_on_error(st);
2445
2446 if (_cm != NULL) {
2447 st->cr();
2448 _cm->print_on_error(st);
2449 }
2450 }
2451
2452 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2453 workers()->print_worker_threads_on(st);
2454 _cmThread->print_on(st);
2455 st->cr();
2456 _cm->print_worker_threads_on(st);
2457 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2458 if (G1StringDedup::is_enabled()) {
2459 G1StringDedup::print_worker_threads_on(st);
2460 }
2461 }
2462
2463 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2464 workers()->threads_do(tc);
2465 tc->do_thread(_cmThread);
2466 _cm->threads_do(tc);
2467 _cg1r->threads_do(tc); // also iterates over the sample thread
2468 if (G1StringDedup::is_enabled()) {
2469 G1StringDedup::threads_do(tc);
2470 }
2471 }
2472
2473 void G1CollectedHeap::print_tracing_info() const {
2474 g1_rem_set()->print_summary_info();
2475 concurrent_mark()->print_summary_info();
2476 }
2477
2478 #ifndef PRODUCT
2479 // Helpful for debugging RSet issues.
2480
2481 class PrintRSetsClosure : public HeapRegionClosure {
2482 private:
2483 const char* _msg;
2484 size_t _occupied_sum;
2485
2486 public:
2487 bool doHeapRegion(HeapRegion* r) {
2488 HeapRegionRemSet* hrrs = r->rem_set();
2489 size_t occupied = hrrs->occupied();
2490 _occupied_sum += occupied;
2491
2492 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2493 if (occupied == 0) {
2494 tty->print_cr(" RSet is empty");
2495 } else {
2496 hrrs->print();
2497 }
2498 tty->print_cr("----------");
2499 return false;
2500 }
2501
2502 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2503 tty->cr();
2504 tty->print_cr("========================================");
2505 tty->print_cr("%s", msg);
2506 tty->cr();
2507 }
2508
2509 ~PrintRSetsClosure() {
2510 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2511 tty->print_cr("========================================");
2512 tty->cr();
2513 }
2514 };
2515
2516 void G1CollectedHeap::print_cset_rsets() {
2517 PrintRSetsClosure cl("Printing CSet RSets");
2518 collection_set_iterate(&cl);
2519 }
2520
2521 void G1CollectedHeap::print_all_rsets() {
2522 PrintRSetsClosure cl("Printing All RSets");;
2523 heap_region_iterate(&cl);
2524 }
2525 #endif // PRODUCT
2526
2527 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2528
2529 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2530 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2531 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2532
2533 size_t eden_capacity_bytes =
2534 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2535
2536 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2537 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2538 eden_capacity_bytes, survivor_used_bytes, num_regions());
2539 }
2540
2541 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2542 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2543 stats->unused(), stats->used(), stats->region_end_waste(),
2544 stats->regions_filled(), stats->direct_allocated(),
2545 stats->failure_used(), stats->failure_waste());
2546 }
2547
2548 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2549 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2550 gc_tracer->report_gc_heap_summary(when, heap_summary);
2551
2552 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2553 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2554 }
2555
2556 G1CollectedHeap* G1CollectedHeap::heap() {
2557 CollectedHeap* heap = Universe::heap();
2558 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2559 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2560 return (G1CollectedHeap*)heap;
2561 }
2562
2563 void G1CollectedHeap::gc_prologue(bool full) {
2564 // always_do_update_barrier = false;
2565 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2566
2567 // This summary needs to be printed before incrementing total collections.
2568 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2569
2570 // Update common counters.
2571 increment_total_collections(full /* full gc */);
2572 if (full) {
2573 increment_old_marking_cycles_started();
2574 reset_gc_time_stamp();
2575 } else {
2576 increment_gc_time_stamp();
2577 }
2578
2579 // Fill TLAB's and such
2580 double start = os::elapsedTime();
2581 accumulate_statistics_all_tlabs();
2582 ensure_parsability(true);
2583 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2584 }
2585
2586 void G1CollectedHeap::gc_epilogue(bool full) {
2587 // Update common counters.
2588 if (full) {
2589 // Update the number of full collections that have been completed.
2590 increment_old_marking_cycles_completed(false /* concurrent */);
2591 }
2592
2593 // We are at the end of the GC. Total collections has already been increased.
2594 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2595
2596 // FIXME: what is this about?
2597 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2598 // is set.
2599 #if defined(COMPILER2) || INCLUDE_JVMCI
2600 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2601 #endif
2602 // always_do_update_barrier = true;
2603
2604 double start = os::elapsedTime();
2605 resize_all_tlabs();
2606 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2607
2608 allocation_context_stats().update(full);
2609
2610 // We have just completed a GC. Update the soft reference
2611 // policy with the new heap occupancy
2612 Universe::update_heap_info_at_gc();
2613 }
2614
2615 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2616 uint gc_count_before,
2617 bool* succeeded,
2618 GCCause::Cause gc_cause) {
2619 assert_heap_not_locked_and_not_at_safepoint();
2620 VM_G1IncCollectionPause op(gc_count_before,
2621 word_size,
2622 false, /* should_initiate_conc_mark */
2623 g1_policy()->max_pause_time_ms(),
2624 gc_cause);
2625
2626 op.set_allocation_context(AllocationContext::current());
2627 VMThread::execute(&op);
2628
2629 HeapWord* result = op.result();
2630 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2631 assert(result == NULL || ret_succeeded,
2632 "the result should be NULL if the VM did not succeed");
2633 *succeeded = ret_succeeded;
2634
2635 assert_heap_not_locked();
2636 return result;
2637 }
2638
2639 void
2640 G1CollectedHeap::doConcurrentMark() {
2641 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2642 if (!_cmThread->in_progress()) {
2643 _cmThread->set_started();
2644 CGC_lock->notify();
2645 }
2646 }
2647
2648 size_t G1CollectedHeap::pending_card_num() {
2649 size_t extra_cards = 0;
2650 JavaThread *curr = Threads::first();
2651 while (curr != NULL) {
2652 DirtyCardQueue& dcq = curr->dirty_card_queue();
2653 extra_cards += dcq.size();
2654 curr = curr->next();
2655 }
2656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2657 size_t buffer_size = dcqs.buffer_size();
2658 size_t buffer_num = dcqs.completed_buffers_num();
2659
2660 return buffer_size * buffer_num + extra_cards;
2661 }
2662
2663 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2664 private:
2665 size_t _total_humongous;
2666 size_t _candidate_humongous;
2667
2668 DirtyCardQueue _dcq;
2669
2670 // We don't nominate objects with many remembered set entries, on
2671 // the assumption that such objects are likely still live.
2672 bool is_remset_small(HeapRegion* region) const {
2673 HeapRegionRemSet* const rset = region->rem_set();
2674 return G1EagerReclaimHumongousObjectsWithStaleRefs
2675 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2676 : rset->is_empty();
2677 }
2678
2679 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2680 assert(region->is_starts_humongous(), "Must start a humongous object");
2681
2682 oop obj = oop(region->bottom());
2683
2684 // Dead objects cannot be eager reclaim candidates. Due to class
2685 // unloading it is unsafe to query their classes so we return early.
2686 if (heap->is_obj_dead(obj, region)) {
2687 return false;
2688 }
2689
2690 // Candidate selection must satisfy the following constraints
2691 // while concurrent marking is in progress:
2692 //
2693 // * In order to maintain SATB invariants, an object must not be
2694 // reclaimed if it was allocated before the start of marking and
2695 // has not had its references scanned. Such an object must have
2696 // its references (including type metadata) scanned to ensure no
2697 // live objects are missed by the marking process. Objects
2698 // allocated after the start of concurrent marking don't need to
2699 // be scanned.
2700 //
2701 // * An object must not be reclaimed if it is on the concurrent
2702 // mark stack. Objects allocated after the start of concurrent
2703 // marking are never pushed on the mark stack.
2704 //
2705 // Nominating only objects allocated after the start of concurrent
2706 // marking is sufficient to meet both constraints. This may miss
2707 // some objects that satisfy the constraints, but the marking data
2708 // structures don't support efficiently performing the needed
2709 // additional tests or scrubbing of the mark stack.
2710 //
2711 // However, we presently only nominate is_typeArray() objects.
2712 // A humongous object containing references induces remembered
2713 // set entries on other regions. In order to reclaim such an
2714 // object, those remembered sets would need to be cleaned up.
2715 //
2716 // We also treat is_typeArray() objects specially, allowing them
2717 // to be reclaimed even if allocated before the start of
2718 // concurrent mark. For this we rely on mark stack insertion to
2719 // exclude is_typeArray() objects, preventing reclaiming an object
2720 // that is in the mark stack. We also rely on the metadata for
2721 // such objects to be built-in and so ensured to be kept live.
2722 // Frequent allocation and drop of large binary blobs is an
2723 // important use case for eager reclaim, and this special handling
2724 // may reduce needed headroom.
2725
2726 return obj->is_typeArray() && is_remset_small(region);
2727 }
2728
2729 public:
2730 RegisterHumongousWithInCSetFastTestClosure()
2731 : _total_humongous(0),
2732 _candidate_humongous(0),
2733 _dcq(&JavaThread::dirty_card_queue_set()) {
2734 }
2735
2736 virtual bool doHeapRegion(HeapRegion* r) {
2737 if (!r->is_starts_humongous()) {
2738 return false;
2739 }
2740 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2741
2742 bool is_candidate = humongous_region_is_candidate(g1h, r);
2743 uint rindex = r->hrm_index();
2744 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2745 if (is_candidate) {
2746 _candidate_humongous++;
2747 g1h->register_humongous_region_with_cset(rindex);
2748 // Is_candidate already filters out humongous object with large remembered sets.
2749 // If we have a humongous object with a few remembered sets, we simply flush these
2750 // remembered set entries into the DCQS. That will result in automatic
2751 // re-evaluation of their remembered set entries during the following evacuation
2752 // phase.
2753 if (!r->rem_set()->is_empty()) {
2754 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2755 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2756 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2757 HeapRegionRemSetIterator hrrs(r->rem_set());
2758 size_t card_index;
2759 while (hrrs.has_next(card_index)) {
2760 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2761 // The remembered set might contain references to already freed
2762 // regions. Filter out such entries to avoid failing card table
2763 // verification.
2764 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2765 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2766 *card_ptr = CardTableModRefBS::dirty_card_val();
2767 _dcq.enqueue(card_ptr);
2768 }
2769 }
2770 }
2771 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2772 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2773 hrrs.n_yielded(), r->rem_set()->occupied());
2774 r->rem_set()->clear_locked();
2775 }
2776 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2777 }
2778 _total_humongous++;
2779
2780 return false;
2781 }
2782
2783 size_t total_humongous() const { return _total_humongous; }
2784 size_t candidate_humongous() const { return _candidate_humongous; }
2785
2786 void flush_rem_set_entries() { _dcq.flush(); }
2787 };
2788
2789 void G1CollectedHeap::register_humongous_regions_with_cset() {
2790 if (!G1EagerReclaimHumongousObjects) {
2791 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2792 return;
2793 }
2794 double time = os::elapsed_counter();
2795
2796 // Collect reclaim candidate information and register candidates with cset.
2797 RegisterHumongousWithInCSetFastTestClosure cl;
2798 heap_region_iterate(&cl);
2799
2800 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2801 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2802 cl.total_humongous(),
2803 cl.candidate_humongous());
2804 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2805
2806 // Finally flush all remembered set entries to re-check into the global DCQS.
2807 cl.flush_rem_set_entries();
2808 }
2809
2810 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2811 public:
2812 bool doHeapRegion(HeapRegion* hr) {
2813 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2814 hr->verify_rem_set();
2815 }
2816 return false;
2817 }
2818 };
2819
2820 uint G1CollectedHeap::num_task_queues() const {
2821 return _task_queues->size();
2822 }
2823
2824 #if TASKQUEUE_STATS
2825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2826 st->print_raw_cr("GC Task Stats");
2827 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2828 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2829 }
2830
2831 void G1CollectedHeap::print_taskqueue_stats() const {
2832 if (!log_is_enabled(Trace, gc, task, stats)) {
2833 return;
2834 }
2835 Log(gc, task, stats) log;
2836 ResourceMark rm;
2837 outputStream* st = log.trace_stream();
2838
2839 print_taskqueue_stats_hdr(st);
2840
2841 TaskQueueStats totals;
2842 const uint n = num_task_queues();
2843 for (uint i = 0; i < n; ++i) {
2844 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2845 totals += task_queue(i)->stats;
2846 }
2847 st->print_raw("tot "); totals.print(st); st->cr();
2848
2849 DEBUG_ONLY(totals.verify());
2850 }
2851
2852 void G1CollectedHeap::reset_taskqueue_stats() {
2853 const uint n = num_task_queues();
2854 for (uint i = 0; i < n; ++i) {
2855 task_queue(i)->stats.reset();
2856 }
2857 }
2858 #endif // TASKQUEUE_STATS
2859
2860 void G1CollectedHeap::wait_for_root_region_scanning() {
2861 double scan_wait_start = os::elapsedTime();
2862 // We have to wait until the CM threads finish scanning the
2863 // root regions as it's the only way to ensure that all the
2864 // objects on them have been correctly scanned before we start
2865 // moving them during the GC.
2866 bool waited = _cm->root_regions()->wait_until_scan_finished();
2867 double wait_time_ms = 0.0;
2868 if (waited) {
2869 double scan_wait_end = os::elapsedTime();
2870 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2871 }
2872 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2873 }
2874
2875 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2876 private:
2877 G1HRPrinter* _hr_printer;
2878 public:
2879 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2880
2881 virtual bool doHeapRegion(HeapRegion* r) {
2882 _hr_printer->cset(r);
2883 return false;
2884 }
2885 };
2886
2887 void G1CollectedHeap::start_new_collection_set() {
2888 collection_set()->start_incremental_building();
2889
2890 clear_cset_fast_test();
2891
2892 guarantee(_eden.length() == 0, "eden should have been cleared");
2893 g1_policy()->transfer_survivors_to_cset(survivor());
2894 }
2895
2896 bool
2897 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2898 assert_at_safepoint(true /* should_be_vm_thread */);
2899 guarantee(!is_gc_active(), "collection is not reentrant");
2900
2901 if (GCLocker::check_active_before_gc()) {
2902 return false;
2903 }
2904
2905 _gc_timer_stw->register_gc_start();
2906
2907 GCIdMark gc_id_mark;
2908 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2909
2910 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2911 ResourceMark rm;
2912
2913 g1_policy()->note_gc_start();
2914
2915 wait_for_root_region_scanning();
2916
2917 print_heap_before_gc();
2918 print_heap_regions();
2919 trace_heap_before_gc(_gc_tracer_stw);
2920
2921 _verifier->verify_region_sets_optional();
2922 _verifier->verify_dirty_young_regions();
2923
2924 // We should not be doing initial mark unless the conc mark thread is running
2925 if (!_cmThread->should_terminate()) {
2926 // This call will decide whether this pause is an initial-mark
2927 // pause. If it is, during_initial_mark_pause() will return true
2928 // for the duration of this pause.
2929 g1_policy()->decide_on_conc_mark_initiation();
2930 }
2931
2932 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2933 assert(!collector_state()->during_initial_mark_pause() ||
2934 collector_state()->gcs_are_young(), "sanity");
2935
2936 // We also do not allow mixed GCs during marking.
2937 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2938
2939 // Record whether this pause is an initial mark. When the current
2940 // thread has completed its logging output and it's safe to signal
2941 // the CM thread, the flag's value in the policy has been reset.
2942 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2943
2944 // Inner scope for scope based logging, timers, and stats collection
2945 {
2946 EvacuationInfo evacuation_info;
2947
2948 if (collector_state()->during_initial_mark_pause()) {
2949 // We are about to start a marking cycle, so we increment the
2950 // full collection counter.
2951 increment_old_marking_cycles_started();
2952 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2953 }
2954
2955 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2956
2957 GCTraceCPUTime tcpu;
2958
2959 FormatBuffer<> gc_string("Pause ");
2960 if (collector_state()->during_initial_mark_pause()) {
2961 gc_string.append("Initial Mark");
2962 } else if (collector_state()->gcs_are_young()) {
2963 gc_string.append("Young");
2964 } else {
2965 gc_string.append("Mixed");
2966 }
2967 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2968
2969 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2970 workers()->active_workers(),
2971 Threads::number_of_non_daemon_threads());
2972 workers()->update_active_workers(active_workers);
2973 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2974
2975 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2976 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2977
2978 // If the secondary_free_list is not empty, append it to the
2979 // free_list. No need to wait for the cleanup operation to finish;
2980 // the region allocation code will check the secondary_free_list
2981 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2982 // set, skip this step so that the region allocation code has to
2983 // get entries from the secondary_free_list.
2984 if (!G1StressConcRegionFreeing) {
2985 append_secondary_free_list_if_not_empty_with_lock();
2986 }
2987
2988 G1HeapTransition heap_transition(this);
2989 size_t heap_used_bytes_before_gc = used();
2990
2991 // Don't dynamically change the number of GC threads this early. A value of
2992 // 0 is used to indicate serial work. When parallel work is done,
2993 // it will be set.
2994
2995 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2996 IsGCActiveMark x;
2997
2998 gc_prologue(false);
2999
3000 if (VerifyRememberedSets) {
3001 log_info(gc, verify)("[Verifying RemSets before GC]");
3002 VerifyRegionRemSetClosure v_cl;
3003 heap_region_iterate(&v_cl);
3004 }
3005
3006 _verifier->verify_before_gc();
3007
3008 _verifier->check_bitmaps("GC Start");
3009
3010 #if defined(COMPILER2) || INCLUDE_JVMCI
3011 DerivedPointerTable::clear();
3012 #endif
3013
3014 // Please see comment in g1CollectedHeap.hpp and
3015 // G1CollectedHeap::ref_processing_init() to see how
3016 // reference processing currently works in G1.
3017
3018 // Enable discovery in the STW reference processor
3019 if (g1_policy()->should_process_references()) {
3020 ref_processor_stw()->enable_discovery();
3021 } else {
3022 ref_processor_stw()->disable_discovery();
3023 }
3024
3025 {
3026 // We want to temporarily turn off discovery by the
3027 // CM ref processor, if necessary, and turn it back on
3028 // on again later if we do. Using a scoped
3029 // NoRefDiscovery object will do this.
3030 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3031
3032 // Forget the current alloc region (we might even choose it to be part
3033 // of the collection set!).
3034 _allocator->release_mutator_alloc_region();
3035
3036 // This timing is only used by the ergonomics to handle our pause target.
3037 // It is unclear why this should not include the full pause. We will
3038 // investigate this in CR 7178365.
3039 //
3040 // Preserving the old comment here if that helps the investigation:
3041 //
3042 // The elapsed time induced by the start time below deliberately elides
3043 // the possible verification above.
3044 double sample_start_time_sec = os::elapsedTime();
3045
3046 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3047
3048 if (collector_state()->during_initial_mark_pause()) {
3049 concurrent_mark()->checkpointRootsInitialPre();
3050 }
3051
3052 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3053
3054 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3055
3056 // Make sure the remembered sets are up to date. This needs to be
3057 // done before register_humongous_regions_with_cset(), because the
3058 // remembered sets are used there to choose eager reclaim candidates.
3059 // If the remembered sets are not up to date we might miss some
3060 // entries that need to be handled.
3061 g1_rem_set()->cleanupHRRS();
3062
3063 register_humongous_regions_with_cset();
3064
3065 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3066
3067 // We call this after finalize_cset() to
3068 // ensure that the CSet has been finalized.
3069 _cm->verify_no_cset_oops();
3070
3071 if (_hr_printer.is_active()) {
3072 G1PrintCollectionSetClosure cl(&_hr_printer);
3073 _collection_set.iterate(&cl);
3074 }
3075
3076 // Initialize the GC alloc regions.
3077 _allocator->init_gc_alloc_regions(evacuation_info);
3078
3079 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3080 pre_evacuate_collection_set();
3081
3082 // Actually do the work...
3083 evacuate_collection_set(evacuation_info, &per_thread_states);
3084
3085 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3086
3087 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3088 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3089
3090 eagerly_reclaim_humongous_regions();
3091
3092 record_obj_copy_mem_stats();
3093 _survivor_evac_stats.adjust_desired_plab_sz();
3094 _old_evac_stats.adjust_desired_plab_sz();
3095
3096 double start = os::elapsedTime();
3097 start_new_collection_set();
3098 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3099
3100 if (evacuation_failed()) {
3101 set_used(recalculate_used());
3102 if (_archive_allocator != NULL) {
3103 _archive_allocator->clear_used();
3104 }
3105 for (uint i = 0; i < ParallelGCThreads; i++) {
3106 if (_evacuation_failed_info_array[i].has_failed()) {
3107 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3108 }
3109 }
3110 } else {
3111 // The "used" of the the collection set have already been subtracted
3112 // when they were freed. Add in the bytes evacuated.
3113 increase_used(g1_policy()->bytes_copied_during_gc());
3114 }
3115
3116 if (collector_state()->during_initial_mark_pause()) {
3117 // We have to do this before we notify the CM threads that
3118 // they can start working to make sure that all the
3119 // appropriate initialization is done on the CM object.
3120 concurrent_mark()->checkpointRootsInitialPost();
3121 collector_state()->set_mark_in_progress(true);
3122 // Note that we don't actually trigger the CM thread at
3123 // this point. We do that later when we're sure that
3124 // the current thread has completed its logging output.
3125 }
3126
3127 allocate_dummy_regions();
3128
3129 _allocator->init_mutator_alloc_region();
3130
3131 {
3132 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3133 if (expand_bytes > 0) {
3134 size_t bytes_before = capacity();
3135 // No need for an ergo logging here,
3136 // expansion_amount() does this when it returns a value > 0.
3137 double expand_ms;
3138 if (!expand(expand_bytes, _workers, &expand_ms)) {
3139 // We failed to expand the heap. Cannot do anything about it.
3140 }
3141 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3142 }
3143 }
3144
3145 // We redo the verification but now wrt to the new CSet which
3146 // has just got initialized after the previous CSet was freed.
3147 _cm->verify_no_cset_oops();
3148
3149 // This timing is only used by the ergonomics to handle our pause target.
3150 // It is unclear why this should not include the full pause. We will
3151 // investigate this in CR 7178365.
3152 double sample_end_time_sec = os::elapsedTime();
3153 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3154 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3155 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3156
3157 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3158 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3159
3160 MemoryService::track_memory_usage();
3161
3162 // In prepare_for_verify() below we'll need to scan the deferred
3163 // update buffers to bring the RSets up-to-date if
3164 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3165 // the update buffers we'll probably need to scan cards on the
3166 // regions we just allocated to (i.e., the GC alloc
3167 // regions). However, during the last GC we called
3168 // set_saved_mark() on all the GC alloc regions, so card
3169 // scanning might skip the [saved_mark_word()...top()] area of
3170 // those regions (i.e., the area we allocated objects into
3171 // during the last GC). But it shouldn't. Given that
3172 // saved_mark_word() is conditional on whether the GC time stamp
3173 // on the region is current or not, by incrementing the GC time
3174 // stamp here we invalidate all the GC time stamps on all the
3175 // regions and saved_mark_word() will simply return top() for
3176 // all the regions. This is a nicer way of ensuring this rather
3177 // than iterating over the regions and fixing them. In fact, the
3178 // GC time stamp increment here also ensures that
3179 // saved_mark_word() will return top() between pauses, i.e.,
3180 // during concurrent refinement. So we don't need the
3181 // is_gc_active() check to decided which top to use when
3182 // scanning cards (see CR 7039627).
3183 increment_gc_time_stamp();
3184
3185 if (VerifyRememberedSets) {
3186 log_info(gc, verify)("[Verifying RemSets after GC]");
3187 VerifyRegionRemSetClosure v_cl;
3188 heap_region_iterate(&v_cl);
3189 }
3190
3191 _verifier->verify_after_gc();
3192 _verifier->check_bitmaps("GC End");
3193
3194 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3195 ref_processor_stw()->verify_no_references_recorded();
3196
3197 // CM reference discovery will be re-enabled if necessary.
3198 }
3199
3200 #ifdef TRACESPINNING
3201 ParallelTaskTerminator::print_termination_counts();
3202 #endif
3203
3204 gc_epilogue(false);
3205 }
3206
3207 // Print the remainder of the GC log output.
3208 if (evacuation_failed()) {
3209 log_info(gc)("To-space exhausted");
3210 }
3211
3212 g1_policy()->print_phases();
3213 heap_transition.print();
3214
3215 // It is not yet to safe to tell the concurrent mark to
3216 // start as we have some optional output below. We don't want the
3217 // output from the concurrent mark thread interfering with this
3218 // logging output either.
3219
3220 _hrm.verify_optional();
3221 _verifier->verify_region_sets_optional();
3222
3223 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3224 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3225
3226 print_heap_after_gc();
3227 print_heap_regions();
3228 trace_heap_after_gc(_gc_tracer_stw);
3229
3230 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3231 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3232 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3233 // before any GC notifications are raised.
3234 g1mm()->update_sizes();
3235
3236 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3237 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3238 _gc_timer_stw->register_gc_end();
3239 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3240 }
3241 // It should now be safe to tell the concurrent mark thread to start
3242 // without its logging output interfering with the logging output
3243 // that came from the pause.
3244
3245 if (should_start_conc_mark) {
3246 // CAUTION: after the doConcurrentMark() call below,
3247 // the concurrent marking thread(s) could be running
3248 // concurrently with us. Make sure that anything after
3249 // this point does not assume that we are the only GC thread
3250 // running. Note: of course, the actual marking work will
3251 // not start until the safepoint itself is released in
3252 // SuspendibleThreadSet::desynchronize().
3253 doConcurrentMark();
3254 }
3255
3256 return true;
3257 }
3258
3259 void G1CollectedHeap::remove_self_forwarding_pointers() {
3260 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3261 workers()->run_task(&rsfp_task);
3262 }
3263
3264 void G1CollectedHeap::restore_after_evac_failure() {
3265 double remove_self_forwards_start = os::elapsedTime();
3266
3267 remove_self_forwarding_pointers();
3268 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3269 _preserved_marks_set.restore(&task_executor);
3270
3271 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3272 }
3273
3274 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3275 if (!_evacuation_failed) {
3276 _evacuation_failed = true;
3277 }
3278
3279 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3280 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3281 }
3282
3283 bool G1ParEvacuateFollowersClosure::offer_termination() {
3284 G1ParScanThreadState* const pss = par_scan_state();
3285 start_term_time();
3286 const bool res = terminator()->offer_termination();
3287 end_term_time();
3288 return res;
3289 }
3290
3291 void G1ParEvacuateFollowersClosure::do_void() {
3292 G1ParScanThreadState* const pss = par_scan_state();
3293 pss->trim_queue();
3294 do {
3295 pss->steal_and_trim_queue(queues());
3296 } while (!offer_termination());
3297 }
3298
3299 class G1ParTask : public AbstractGangTask {
3300 protected:
3301 G1CollectedHeap* _g1h;
3302 G1ParScanThreadStateSet* _pss;
3303 RefToScanQueueSet* _queues;
3304 G1RootProcessor* _root_processor;
3305 ParallelTaskTerminator _terminator;
3306 uint _n_workers;
3307
3308 public:
3309 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3310 : AbstractGangTask("G1 collection"),
3311 _g1h(g1h),
3312 _pss(per_thread_states),
3313 _queues(task_queues),
3314 _root_processor(root_processor),
3315 _terminator(n_workers, _queues),
3316 _n_workers(n_workers)
3317 {}
3318
3319 void work(uint worker_id) {
3320 if (worker_id >= _n_workers) return; // no work needed this round
3321
3322 double start_sec = os::elapsedTime();
3323 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3324
3325 {
3326 ResourceMark rm;
3327 HandleMark hm;
3328
3329 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3330
3331 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3332 pss->set_ref_processor(rp);
3333
3334 double start_strong_roots_sec = os::elapsedTime();
3335
3336 _root_processor->evacuate_roots(pss->closures(), worker_id);
3337
3338 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3339
3340 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3341 // treating the nmethods visited to act as roots for concurrent marking.
3342 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3343 // objects copied by the current evacuation.
3344 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3345 pss->closures()->weak_codeblobs(),
3346 worker_id);
3347
3348 _pss->add_cards_scanned(worker_id, cards_scanned);
3349
3350 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3351
3352 double term_sec = 0.0;
3353 size_t evac_term_attempts = 0;
3354 {
3355 double start = os::elapsedTime();
3356 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3357 evac.do_void();
3358
3359 evac_term_attempts = evac.term_attempts();
3360 term_sec = evac.term_time();
3361 double elapsed_sec = os::elapsedTime() - start;
3362 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3363 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3364 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3365 }
3366
3367 assert(pss->queue_is_empty(), "should be empty");
3368
3369 if (log_is_enabled(Debug, gc, task, stats)) {
3370 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3371 size_t lab_waste;
3372 size_t lab_undo_waste;
3373 pss->waste(lab_waste, lab_undo_waste);
3374 _g1h->print_termination_stats(worker_id,
3375 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3376 strong_roots_sec * 1000.0, /* strong roots time */
3377 term_sec * 1000.0, /* evac term time */
3378 evac_term_attempts, /* evac term attempts */
3379 lab_waste, /* alloc buffer waste */
3380 lab_undo_waste /* undo waste */
3381 );
3382 }
3383
3384 // Close the inner scope so that the ResourceMark and HandleMark
3385 // destructors are executed here and are included as part of the
3386 // "GC Worker Time".
3387 }
3388 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3389 }
3390 };
3391
3392 void G1CollectedHeap::print_termination_stats_hdr() {
3393 log_debug(gc, task, stats)("GC Termination Stats");
3394 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3395 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3396 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3397 }
3398
3399 void G1CollectedHeap::print_termination_stats(uint worker_id,
3400 double elapsed_ms,
3401 double strong_roots_ms,
3402 double term_ms,
3403 size_t term_attempts,
3404 size_t alloc_buffer_waste,
3405 size_t undo_waste) const {
3406 log_debug(gc, task, stats)
3407 ("%3d %9.2f %9.2f %6.2f "
3408 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3409 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3410 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3411 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3412 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3413 alloc_buffer_waste * HeapWordSize / K,
3414 undo_waste * HeapWordSize / K);
3415 }
3416
3417 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3418 private:
3419 BoolObjectClosure* _is_alive;
3420 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3421
3422 int _initial_string_table_size;
3423 int _initial_symbol_table_size;
3424
3425 bool _process_strings;
3426 int _strings_processed;
3427 int _strings_removed;
3428
3429 bool _process_symbols;
3430 int _symbols_processed;
3431 int _symbols_removed;
3432
3433 bool _process_string_dedup;
3434
3435 public:
3436 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3437 AbstractGangTask("String/Symbol Unlinking"),
3438 _is_alive(is_alive),
3439 _dedup_closure(is_alive, NULL, false),
3440 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3441 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3442 _process_string_dedup(process_string_dedup) {
3443
3444 _initial_string_table_size = StringTable::the_table()->table_size();
3445 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3446 if (process_strings) {
3447 StringTable::clear_parallel_claimed_index();
3448 }
3449 if (process_symbols) {
3450 SymbolTable::clear_parallel_claimed_index();
3451 }
3452 }
3453
3454 ~G1StringAndSymbolCleaningTask() {
3455 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3456 "claim value %d after unlink less than initial string table size %d",
3457 StringTable::parallel_claimed_index(), _initial_string_table_size);
3458 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3459 "claim value %d after unlink less than initial symbol table size %d",
3460 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3461
3462 log_info(gc, stringtable)(
3463 "Cleaned string and symbol table, "
3464 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3465 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3466 strings_processed(), strings_removed(),
3467 symbols_processed(), symbols_removed());
3468 }
3469
3470 void work(uint worker_id) {
3471 int strings_processed = 0;
3472 int strings_removed = 0;
3473 int symbols_processed = 0;
3474 int symbols_removed = 0;
3475 if (_process_strings) {
3476 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3477 Atomic::add(strings_processed, &_strings_processed);
3478 Atomic::add(strings_removed, &_strings_removed);
3479 }
3480 if (_process_symbols) {
3481 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3482 Atomic::add(symbols_processed, &_symbols_processed);
3483 Atomic::add(symbols_removed, &_symbols_removed);
3484 }
3485 if (_process_string_dedup) {
3486 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3487 }
3488 }
3489
3490 size_t strings_processed() const { return (size_t)_strings_processed; }
3491 size_t strings_removed() const { return (size_t)_strings_removed; }
3492
3493 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3494 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3495 };
3496
3497 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3498 private:
3499 static Monitor* _lock;
3500
3501 BoolObjectClosure* const _is_alive;
3502 const bool _unloading_occurred;
3503 const uint _num_workers;
3504
3505 // Variables used to claim nmethods.
3506 CompiledMethod* _first_nmethod;
3507 volatile CompiledMethod* _claimed_nmethod;
3508
3509 // The list of nmethods that need to be processed by the second pass.
3510 volatile CompiledMethod* _postponed_list;
3511 volatile uint _num_entered_barrier;
3512
3513 public:
3514 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3515 _is_alive(is_alive),
3516 _unloading_occurred(unloading_occurred),
3517 _num_workers(num_workers),
3518 _first_nmethod(NULL),
3519 _claimed_nmethod(NULL),
3520 _postponed_list(NULL),
3521 _num_entered_barrier(0)
3522 {
3523 CompiledMethod::increase_unloading_clock();
3524 // Get first alive nmethod
3525 CompiledMethodIterator iter = CompiledMethodIterator();
3526 if(iter.next_alive()) {
3527 _first_nmethod = iter.method();
3528 }
3529 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3530 }
3531
3532 ~G1CodeCacheUnloadingTask() {
3533 CodeCache::verify_clean_inline_caches();
3534
3535 CodeCache::set_needs_cache_clean(false);
3536 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3537
3538 CodeCache::verify_icholder_relocations();
3539 }
3540
3541 private:
3542 void add_to_postponed_list(CompiledMethod* nm) {
3543 CompiledMethod* old;
3544 do {
3545 old = (CompiledMethod*)_postponed_list;
3546 nm->set_unloading_next(old);
3547 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3548 }
3549
3550 void clean_nmethod(CompiledMethod* nm) {
3551 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3552
3553 if (postponed) {
3554 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3555 add_to_postponed_list(nm);
3556 }
3557
3558 // Mark that this thread has been cleaned/unloaded.
3559 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3560 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3561 }
3562
3563 void clean_nmethod_postponed(CompiledMethod* nm) {
3564 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3565 }
3566
3567 static const int MaxClaimNmethods = 16;
3568
3569 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3570 CompiledMethod* first;
3571 CompiledMethodIterator last;
3572
3573 do {
3574 *num_claimed_nmethods = 0;
3575
3576 first = (CompiledMethod*)_claimed_nmethod;
3577 last = CompiledMethodIterator(first);
3578
3579 if (first != NULL) {
3580
3581 for (int i = 0; i < MaxClaimNmethods; i++) {
3582 if (!last.next_alive()) {
3583 break;
3584 }
3585 claimed_nmethods[i] = last.method();
3586 (*num_claimed_nmethods)++;
3587 }
3588 }
3589
3590 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3591 }
3592
3593 CompiledMethod* claim_postponed_nmethod() {
3594 CompiledMethod* claim;
3595 CompiledMethod* next;
3596
3597 do {
3598 claim = (CompiledMethod*)_postponed_list;
3599 if (claim == NULL) {
3600 return NULL;
3601 }
3602
3603 next = claim->unloading_next();
3604
3605 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3606
3607 return claim;
3608 }
3609
3610 public:
3611 // Mark that we're done with the first pass of nmethod cleaning.
3612 void barrier_mark(uint worker_id) {
3613 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3614 _num_entered_barrier++;
3615 if (_num_entered_barrier == _num_workers) {
3616 ml.notify_all();
3617 }
3618 }
3619
3620 // See if we have to wait for the other workers to
3621 // finish their first-pass nmethod cleaning work.
3622 void barrier_wait(uint worker_id) {
3623 if (_num_entered_barrier < _num_workers) {
3624 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3625 while (_num_entered_barrier < _num_workers) {
3626 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3627 }
3628 }
3629 }
3630
3631 // Cleaning and unloading of nmethods. Some work has to be postponed
3632 // to the second pass, when we know which nmethods survive.
3633 void work_first_pass(uint worker_id) {
3634 // The first nmethods is claimed by the first worker.
3635 if (worker_id == 0 && _first_nmethod != NULL) {
3636 clean_nmethod(_first_nmethod);
3637 _first_nmethod = NULL;
3638 }
3639
3640 int num_claimed_nmethods;
3641 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3642
3643 while (true) {
3644 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3645
3646 if (num_claimed_nmethods == 0) {
3647 break;
3648 }
3649
3650 for (int i = 0; i < num_claimed_nmethods; i++) {
3651 clean_nmethod(claimed_nmethods[i]);
3652 }
3653 }
3654 }
3655
3656 void work_second_pass(uint worker_id) {
3657 CompiledMethod* nm;
3658 // Take care of postponed nmethods.
3659 while ((nm = claim_postponed_nmethod()) != NULL) {
3660 clean_nmethod_postponed(nm);
3661 }
3662 }
3663 };
3664
3665 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3666
3667 class G1KlassCleaningTask : public StackObj {
3668 BoolObjectClosure* _is_alive;
3669 volatile jint _clean_klass_tree_claimed;
3670 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3671
3672 public:
3673 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3674 _is_alive(is_alive),
3675 _clean_klass_tree_claimed(0),
3676 _klass_iterator() {
3677 }
3678
3679 private:
3680 bool claim_clean_klass_tree_task() {
3681 if (_clean_klass_tree_claimed) {
3682 return false;
3683 }
3684
3685 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3686 }
3687
3688 InstanceKlass* claim_next_klass() {
3689 Klass* klass;
3690 do {
3691 klass =_klass_iterator.next_klass();
3692 } while (klass != NULL && !klass->is_instance_klass());
3693
3694 // this can be null so don't call InstanceKlass::cast
3695 return static_cast<InstanceKlass*>(klass);
3696 }
3697
3698 public:
3699
3700 void clean_klass(InstanceKlass* ik) {
3701 ik->clean_weak_instanceklass_links(_is_alive);
3702 }
3703
3704 void work() {
3705 ResourceMark rm;
3706
3707 // One worker will clean the subklass/sibling klass tree.
3708 if (claim_clean_klass_tree_task()) {
3709 Klass::clean_subklass_tree(_is_alive);
3710 }
3711
3712 // All workers will help cleaning the classes,
3713 InstanceKlass* klass;
3714 while ((klass = claim_next_klass()) != NULL) {
3715 clean_klass(klass);
3716 }
3717 }
3718 };
3719
3720 class G1ResolvedMethodCleaningTask : public StackObj {
3721 BoolObjectClosure* _is_alive;
3722 volatile jint _resolved_method_task_claimed;
3723 public:
3724 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3725 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3726
3727 bool claim_resolved_method_task() {
3728 if (_resolved_method_task_claimed) {
3729 return false;
3730 }
3731 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3732 }
3733
3734 // These aren't big, one thread can do it all.
3735 void work() {
3736 if (claim_resolved_method_task()) {
3737 ResolvedMethodTable::unlink(_is_alive);
3738 }
3739 }
3740 };
3741
3742
3743 // To minimize the remark pause times, the tasks below are done in parallel.
3744 class G1ParallelCleaningTask : public AbstractGangTask {
3745 private:
3746 G1StringAndSymbolCleaningTask _string_symbol_task;
3747 G1CodeCacheUnloadingTask _code_cache_task;
3748 G1KlassCleaningTask _klass_cleaning_task;
3749 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3750
3751 public:
3752 // The constructor is run in the VMThread.
3753 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3754 AbstractGangTask("Parallel Cleaning"),
3755 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3756 _code_cache_task(num_workers, is_alive, unloading_occurred),
3757 _klass_cleaning_task(is_alive),
3758 _resolved_method_cleaning_task(is_alive) {
3759 }
3760
3761 // The parallel work done by all worker threads.
3762 void work(uint worker_id) {
3763 // Do first pass of code cache cleaning.
3764 _code_cache_task.work_first_pass(worker_id);
3765
3766 // Let the threads mark that the first pass is done.
3767 _code_cache_task.barrier_mark(worker_id);
3768
3769 // Clean the Strings and Symbols.
3770 _string_symbol_task.work(worker_id);
3771
3772 // Clean unreferenced things in the ResolvedMethodTable
3773 _resolved_method_cleaning_task.work();
3774
3775 // Wait for all workers to finish the first code cache cleaning pass.
3776 _code_cache_task.barrier_wait(worker_id);
3777
3778 // Do the second code cache cleaning work, which realize on
3779 // the liveness information gathered during the first pass.
3780 _code_cache_task.work_second_pass(worker_id);
3781
3782 // Clean all klasses that were not unloaded.
3783 _klass_cleaning_task.work();
3784 }
3785 };
3786
3787
3788 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3789 bool class_unloading_occurred) {
3790 uint n_workers = workers()->active_workers();
3791
3792 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3793 workers()->run_task(&g1_unlink_task);
3794 }
3795
3796 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3797 bool process_strings,
3798 bool process_symbols,
3799 bool process_string_dedup) {
3800 if (!process_strings && !process_symbols && !process_string_dedup) {
3801 // Nothing to clean.
3802 return;
3803 }
3804
3805 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3806 workers()->run_task(&g1_unlink_task);
3807
3808 }
3809
3810 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3811 private:
3812 DirtyCardQueueSet* _queue;
3813 G1CollectedHeap* _g1h;
3814 public:
3815 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3816 _queue(queue), _g1h(g1h) { }
3817
3818 virtual void work(uint worker_id) {
3819 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3820 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3821
3822 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3823 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3824
3825 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3826 }
3827 };
3828
3829 void G1CollectedHeap::redirty_logged_cards() {
3830 double redirty_logged_cards_start = os::elapsedTime();
3831
3832 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3833 dirty_card_queue_set().reset_for_par_iteration();
3834 workers()->run_task(&redirty_task);
3835
3836 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3837 dcq.merge_bufferlists(&dirty_card_queue_set());
3838 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3839
3840 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3841 }
3842
3843 // Weak Reference Processing support
3844
3845 // An always "is_alive" closure that is used to preserve referents.
3846 // If the object is non-null then it's alive. Used in the preservation
3847 // of referent objects that are pointed to by reference objects
3848 // discovered by the CM ref processor.
3849 class G1AlwaysAliveClosure: public BoolObjectClosure {
3850 G1CollectedHeap* _g1;
3851 public:
3852 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3853 bool do_object_b(oop p) {
3854 if (p != NULL) {
3855 return true;
3856 }
3857 return false;
3858 }
3859 };
3860
3861 bool G1STWIsAliveClosure::do_object_b(oop p) {
3862 // An object is reachable if it is outside the collection set,
3863 // or is inside and copied.
3864 return !_g1->is_in_cset(p) || p->is_forwarded();
3865 }
3866
3867 // Non Copying Keep Alive closure
3868 class G1KeepAliveClosure: public OopClosure {
3869 G1CollectedHeap* _g1;
3870 public:
3871 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3872 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3873 void do_oop(oop* p) {
3874 oop obj = *p;
3875 assert(obj != NULL, "the caller should have filtered out NULL values");
3876
3877 const InCSetState cset_state = _g1->in_cset_state(obj);
3878 if (!cset_state.is_in_cset_or_humongous()) {
3879 return;
3880 }
3881 if (cset_state.is_in_cset()) {
3882 assert( obj->is_forwarded(), "invariant" );
3883 *p = obj->forwardee();
3884 } else {
3885 assert(!obj->is_forwarded(), "invariant" );
3886 assert(cset_state.is_humongous(),
3887 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3888 _g1->set_humongous_is_live(obj);
3889 }
3890 }
3891 };
3892
3893 // Copying Keep Alive closure - can be called from both
3894 // serial and parallel code as long as different worker
3895 // threads utilize different G1ParScanThreadState instances
3896 // and different queues.
3897
3898 class G1CopyingKeepAliveClosure: public OopClosure {
3899 G1CollectedHeap* _g1h;
3900 OopClosure* _copy_non_heap_obj_cl;
3901 G1ParScanThreadState* _par_scan_state;
3902
3903 public:
3904 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3905 OopClosure* non_heap_obj_cl,
3906 G1ParScanThreadState* pss):
3907 _g1h(g1h),
3908 _copy_non_heap_obj_cl(non_heap_obj_cl),
3909 _par_scan_state(pss)
3910 {}
3911
3912 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3913 virtual void do_oop( oop* p) { do_oop_work(p); }
3914
3915 template <class T> void do_oop_work(T* p) {
3916 oop obj = oopDesc::load_decode_heap_oop(p);
3917
3918 if (_g1h->is_in_cset_or_humongous(obj)) {
3919 // If the referent object has been forwarded (either copied
3920 // to a new location or to itself in the event of an
3921 // evacuation failure) then we need to update the reference
3922 // field and, if both reference and referent are in the G1
3923 // heap, update the RSet for the referent.
3924 //
3925 // If the referent has not been forwarded then we have to keep
3926 // it alive by policy. Therefore we have copy the referent.
3927 //
3928 // If the reference field is in the G1 heap then we can push
3929 // on the PSS queue. When the queue is drained (after each
3930 // phase of reference processing) the object and it's followers
3931 // will be copied, the reference field set to point to the
3932 // new location, and the RSet updated. Otherwise we need to
3933 // use the the non-heap or metadata closures directly to copy
3934 // the referent object and update the pointer, while avoiding
3935 // updating the RSet.
3936
3937 if (_g1h->is_in_g1_reserved(p)) {
3938 _par_scan_state->push_on_queue(p);
3939 } else {
3940 assert(!Metaspace::contains((const void*)p),
3941 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3942 _copy_non_heap_obj_cl->do_oop(p);
3943 }
3944 }
3945 }
3946 };
3947
3948 // Serial drain queue closure. Called as the 'complete_gc'
3949 // closure for each discovered list in some of the
3950 // reference processing phases.
3951
3952 class G1STWDrainQueueClosure: public VoidClosure {
3953 protected:
3954 G1CollectedHeap* _g1h;
3955 G1ParScanThreadState* _par_scan_state;
3956
3957 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3958
3959 public:
3960 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3961 _g1h(g1h),
3962 _par_scan_state(pss)
3963 { }
3964
3965 void do_void() {
3966 G1ParScanThreadState* const pss = par_scan_state();
3967 pss->trim_queue();
3968 }
3969 };
3970
3971 // Parallel Reference Processing closures
3972
3973 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3974 // processing during G1 evacuation pauses.
3975
3976 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3977 private:
3978 G1CollectedHeap* _g1h;
3979 G1ParScanThreadStateSet* _pss;
3980 RefToScanQueueSet* _queues;
3981 WorkGang* _workers;
3982 uint _active_workers;
3983
3984 public:
3985 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3986 G1ParScanThreadStateSet* per_thread_states,
3987 WorkGang* workers,
3988 RefToScanQueueSet *task_queues,
3989 uint n_workers) :
3990 _g1h(g1h),
3991 _pss(per_thread_states),
3992 _queues(task_queues),
3993 _workers(workers),
3994 _active_workers(n_workers)
3995 {
3996 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3997 }
3998
3999 // Executes the given task using concurrent marking worker threads.
4000 virtual void execute(ProcessTask& task);
4001 virtual void execute(EnqueueTask& task);
4002 };
4003
4004 // Gang task for possibly parallel reference processing
4005
4006 class G1STWRefProcTaskProxy: public AbstractGangTask {
4007 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4008 ProcessTask& _proc_task;
4009 G1CollectedHeap* _g1h;
4010 G1ParScanThreadStateSet* _pss;
4011 RefToScanQueueSet* _task_queues;
4012 ParallelTaskTerminator* _terminator;
4013
4014 public:
4015 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4016 G1CollectedHeap* g1h,
4017 G1ParScanThreadStateSet* per_thread_states,
4018 RefToScanQueueSet *task_queues,
4019 ParallelTaskTerminator* terminator) :
4020 AbstractGangTask("Process reference objects in parallel"),
4021 _proc_task(proc_task),
4022 _g1h(g1h),
4023 _pss(per_thread_states),
4024 _task_queues(task_queues),
4025 _terminator(terminator)
4026 {}
4027
4028 virtual void work(uint worker_id) {
4029 // The reference processing task executed by a single worker.
4030 ResourceMark rm;
4031 HandleMark hm;
4032
4033 G1STWIsAliveClosure is_alive(_g1h);
4034
4035 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4036 pss->set_ref_processor(NULL);
4037
4038 // Keep alive closure.
4039 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4040
4041 // Complete GC closure
4042 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4043
4044 // Call the reference processing task's work routine.
4045 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4046
4047 // Note we cannot assert that the refs array is empty here as not all
4048 // of the processing tasks (specifically phase2 - pp2_work) execute
4049 // the complete_gc closure (which ordinarily would drain the queue) so
4050 // the queue may not be empty.
4051 }
4052 };
4053
4054 // Driver routine for parallel reference processing.
4055 // Creates an instance of the ref processing gang
4056 // task and has the worker threads execute it.
4057 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4058 assert(_workers != NULL, "Need parallel worker threads.");
4059
4060 ParallelTaskTerminator terminator(_active_workers, _queues);
4061 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4062
4063 _workers->run_task(&proc_task_proxy);
4064 }
4065
4066 // Gang task for parallel reference enqueueing.
4067
4068 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4069 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4070 EnqueueTask& _enq_task;
4071
4072 public:
4073 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4074 AbstractGangTask("Enqueue reference objects in parallel"),
4075 _enq_task(enq_task)
4076 { }
4077
4078 virtual void work(uint worker_id) {
4079 _enq_task.work(worker_id);
4080 }
4081 };
4082
4083 // Driver routine for parallel reference enqueueing.
4084 // Creates an instance of the ref enqueueing gang
4085 // task and has the worker threads execute it.
4086
4087 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4088 assert(_workers != NULL, "Need parallel worker threads.");
4089
4090 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4091
4092 _workers->run_task(&enq_task_proxy);
4093 }
4094
4095 // End of weak reference support closures
4096
4097 // Abstract task used to preserve (i.e. copy) any referent objects
4098 // that are in the collection set and are pointed to by reference
4099 // objects discovered by the CM ref processor.
4100
4101 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4102 protected:
4103 G1CollectedHeap* _g1h;
4104 G1ParScanThreadStateSet* _pss;
4105 RefToScanQueueSet* _queues;
4106 ParallelTaskTerminator _terminator;
4107 uint _n_workers;
4108
4109 public:
4110 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4111 AbstractGangTask("ParPreserveCMReferents"),
4112 _g1h(g1h),
4113 _pss(per_thread_states),
4114 _queues(task_queues),
4115 _terminator(workers, _queues),
4116 _n_workers(workers)
4117 {
4118 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4119 }
4120
4121 void work(uint worker_id) {
4122 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4123
4124 ResourceMark rm;
4125 HandleMark hm;
4126
4127 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4128 pss->set_ref_processor(NULL);
4129 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4130
4131 // Is alive closure
4132 G1AlwaysAliveClosure always_alive(_g1h);
4133
4134 // Copying keep alive closure. Applied to referent objects that need
4135 // to be copied.
4136 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4137
4138 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4139
4140 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4141 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4142
4143 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4144 // So this must be true - but assert just in case someone decides to
4145 // change the worker ids.
4146 assert(worker_id < limit, "sanity");
4147 assert(!rp->discovery_is_atomic(), "check this code");
4148
4149 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4150 for (uint idx = worker_id; idx < limit; idx += stride) {
4151 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4152
4153 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4154 while (iter.has_next()) {
4155 // Since discovery is not atomic for the CM ref processor, we
4156 // can see some null referent objects.
4157 iter.load_ptrs(DEBUG_ONLY(true));
4158 oop ref = iter.obj();
4159
4160 // This will filter nulls.
4161 if (iter.is_referent_alive()) {
4162 iter.make_referent_alive();
4163 }
4164 iter.move_to_next();
4165 }
4166 }
4167
4168 // Drain the queue - which may cause stealing
4169 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4170 drain_queue.do_void();
4171 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4172 assert(pss->queue_is_empty(), "should be");
4173 }
4174 };
4175
4176 void G1CollectedHeap::process_weak_jni_handles() {
4177 double ref_proc_start = os::elapsedTime();
4178
4179 G1STWIsAliveClosure is_alive(this);
4180 G1KeepAliveClosure keep_alive(this);
4181 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4182
4183 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4184 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4185 }
4186
4187 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4188 // Any reference objects, in the collection set, that were 'discovered'
4189 // by the CM ref processor should have already been copied (either by
4190 // applying the external root copy closure to the discovered lists, or
4191 // by following an RSet entry).
4192 //
4193 // But some of the referents, that are in the collection set, that these
4194 // reference objects point to may not have been copied: the STW ref
4195 // processor would have seen that the reference object had already
4196 // been 'discovered' and would have skipped discovering the reference,
4197 // but would not have treated the reference object as a regular oop.
4198 // As a result the copy closure would not have been applied to the
4199 // referent object.
4200 //
4201 // We need to explicitly copy these referent objects - the references
4202 // will be processed at the end of remarking.
4203 //
4204 // We also need to do this copying before we process the reference
4205 // objects discovered by the STW ref processor in case one of these
4206 // referents points to another object which is also referenced by an
4207 // object discovered by the STW ref processor.
4208 double preserve_cm_referents_time = 0.0;
4209
4210 // To avoid spawning task when there is no work to do, check that
4211 // a concurrent cycle is active and that some references have been
4212 // discovered.
4213 if (concurrent_mark()->cmThread()->during_cycle() &&
4214 ref_processor_cm()->has_discovered_references()) {
4215 double preserve_cm_referents_start = os::elapsedTime();
4216 uint no_of_gc_workers = workers()->active_workers();
4217 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4218 per_thread_states,
4219 no_of_gc_workers,
4220 _task_queues);
4221 workers()->run_task(&keep_cm_referents);
4222 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4223 }
4224
4225 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4226 }
4227
4228 // Weak Reference processing during an evacuation pause (part 1).
4229 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4230 double ref_proc_start = os::elapsedTime();
4231
4232 ReferenceProcessor* rp = _ref_processor_stw;
4233 assert(rp->discovery_enabled(), "should have been enabled");
4234
4235 // Closure to test whether a referent is alive.
4236 G1STWIsAliveClosure is_alive(this);
4237
4238 // Even when parallel reference processing is enabled, the processing
4239 // of JNI refs is serial and performed serially by the current thread
4240 // rather than by a worker. The following PSS will be used for processing
4241 // JNI refs.
4242
4243 // Use only a single queue for this PSS.
4244 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4245 pss->set_ref_processor(NULL);
4246 assert(pss->queue_is_empty(), "pre-condition");
4247
4248 // Keep alive closure.
4249 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4250
4251 // Serial Complete GC closure
4252 G1STWDrainQueueClosure drain_queue(this, pss);
4253
4254 // Setup the soft refs policy...
4255 rp->setup_policy(false);
4256
4257 ReferenceProcessorStats stats;
4258 if (!rp->processing_is_mt()) {
4259 // Serial reference processing...
4260 stats = rp->process_discovered_references(&is_alive,
4261 &keep_alive,
4262 &drain_queue,
4263 NULL,
4264 _gc_timer_stw);
4265 } else {
4266 uint no_of_gc_workers = workers()->active_workers();
4267
4268 // Parallel reference processing
4269 assert(no_of_gc_workers <= rp->max_num_q(),
4270 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4271 no_of_gc_workers, rp->max_num_q());
4272
4273 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4274 stats = rp->process_discovered_references(&is_alive,
4275 &keep_alive,
4276 &drain_queue,
4277 &par_task_executor,
4278 _gc_timer_stw);
4279 }
4280
4281 _gc_tracer_stw->report_gc_reference_stats(stats);
4282
4283 // We have completed copying any necessary live referent objects.
4284 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4285
4286 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4287 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4288 }
4289
4290 // Weak Reference processing during an evacuation pause (part 2).
4291 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4292 double ref_enq_start = os::elapsedTime();
4293
4294 ReferenceProcessor* rp = _ref_processor_stw;
4295 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4296
4297 // Now enqueue any remaining on the discovered lists on to
4298 // the pending list.
4299 if (!rp->processing_is_mt()) {
4300 // Serial reference processing...
4301 rp->enqueue_discovered_references();
4302 } else {
4303 // Parallel reference enqueueing
4304
4305 uint n_workers = workers()->active_workers();
4306
4307 assert(n_workers <= rp->max_num_q(),
4308 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4309 n_workers, rp->max_num_q());
4310
4311 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4312 rp->enqueue_discovered_references(&par_task_executor);
4313 }
4314
4315 rp->verify_no_references_recorded();
4316 assert(!rp->discovery_enabled(), "should have been disabled");
4317
4318 // FIXME
4319 // CM's reference processing also cleans up the string and symbol tables.
4320 // Should we do that here also? We could, but it is a serial operation
4321 // and could significantly increase the pause time.
4322
4323 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4324 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4325 }
4326
4327 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4328 double merge_pss_time_start = os::elapsedTime();
4329 per_thread_states->flush();
4330 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4331 }
4332
4333 void G1CollectedHeap::pre_evacuate_collection_set() {
4334 _expand_heap_after_alloc_failure = true;
4335 _evacuation_failed = false;
4336
4337 // Disable the hot card cache.
4338 _hot_card_cache->reset_hot_cache_claimed_index();
4339 _hot_card_cache->set_use_cache(false);
4340
4341 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4342 _preserved_marks_set.assert_empty();
4343
4344 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4345
4346 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4347 if (collector_state()->during_initial_mark_pause()) {
4348 double start_clear_claimed_marks = os::elapsedTime();
4349
4350 ClassLoaderDataGraph::clear_claimed_marks();
4351
4352 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4353 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4354 }
4355 }
4356
4357 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4358 // Should G1EvacuationFailureALot be in effect for this GC?
4359 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4360
4361 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4362
4363 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4364
4365 double start_par_time_sec = os::elapsedTime();
4366 double end_par_time_sec;
4367
4368 {
4369 const uint n_workers = workers()->active_workers();
4370 G1RootProcessor root_processor(this, n_workers);
4371 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4372
4373 print_termination_stats_hdr();
4374
4375 workers()->run_task(&g1_par_task);
4376 end_par_time_sec = os::elapsedTime();
4377
4378 // Closing the inner scope will execute the destructor
4379 // for the G1RootProcessor object. We record the current
4380 // elapsed time before closing the scope so that time
4381 // taken for the destructor is NOT included in the
4382 // reported parallel time.
4383 }
4384
4385 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4386 phase_times->record_par_time(par_time_ms);
4387
4388 double code_root_fixup_time_ms =
4389 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4390 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4391 }
4392
4393 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4394 // Process any discovered reference objects - we have
4395 // to do this _before_ we retire the GC alloc regions
4396 // as we may have to copy some 'reachable' referent
4397 // objects (and their reachable sub-graphs) that were
4398 // not copied during the pause.
4399 if (g1_policy()->should_process_references()) {
4400 preserve_cm_referents(per_thread_states);
4401 process_discovered_references(per_thread_states);
4402 } else {
4403 ref_processor_stw()->verify_no_references_recorded();
4404 process_weak_jni_handles();
4405 }
4406
4407 if (G1StringDedup::is_enabled()) {
4408 double fixup_start = os::elapsedTime();
4409
4410 G1STWIsAliveClosure is_alive(this);
4411 G1KeepAliveClosure keep_alive(this);
4412 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4413
4414 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4415 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4416 }
4417
4418 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4419
4420 if (evacuation_failed()) {
4421 restore_after_evac_failure();
4422
4423 // Reset the G1EvacuationFailureALot counters and flags
4424 // Note: the values are reset only when an actual
4425 // evacuation failure occurs.
4426 NOT_PRODUCT(reset_evacuation_should_fail();)
4427 }
4428
4429 _preserved_marks_set.assert_empty();
4430
4431 // Enqueue any remaining references remaining on the STW
4432 // reference processor's discovered lists. We need to do
4433 // this after the card table is cleaned (and verified) as
4434 // the act of enqueueing entries on to the pending list
4435 // will log these updates (and dirty their associated
4436 // cards). We need these updates logged to update any
4437 // RSets.
4438 if (g1_policy()->should_process_references()) {
4439 enqueue_discovered_references(per_thread_states);
4440 } else {
4441 g1_policy()->phase_times()->record_ref_enq_time(0);
4442 }
4443
4444 _allocator->release_gc_alloc_regions(evacuation_info);
4445
4446 merge_per_thread_state_info(per_thread_states);
4447
4448 // Reset and re-enable the hot card cache.
4449 // Note the counts for the cards in the regions in the
4450 // collection set are reset when the collection set is freed.
4451 _hot_card_cache->reset_hot_cache();
4452 _hot_card_cache->set_use_cache(true);
4453
4454 purge_code_root_memory();
4455
4456 redirty_logged_cards();
4457 #if defined(COMPILER2) || INCLUDE_JVMCI
4458 double start = os::elapsedTime();
4459 DerivedPointerTable::update_pointers();
4460 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4461 #endif
4462 g1_policy()->print_age_table();
4463 }
4464
4465 void G1CollectedHeap::record_obj_copy_mem_stats() {
4466 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4467
4468 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4469 create_g1_evac_summary(&_old_evac_stats));
4470 }
4471
4472 void G1CollectedHeap::free_region(HeapRegion* hr,
4473 FreeRegionList* free_list,
4474 bool skip_remset,
4475 bool skip_hot_card_cache,
4476 bool locked) {
4477 assert(!hr->is_free(), "the region should not be free");
4478 assert(!hr->is_empty(), "the region should not be empty");
4479 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4480 assert(free_list != NULL, "pre-condition");
4481
4482 if (G1VerifyBitmaps) {
4483 MemRegion mr(hr->bottom(), hr->end());
4484 concurrent_mark()->clearRangePrevBitmap(mr);
4485 }
4486
4487 // Clear the card counts for this region.
4488 // Note: we only need to do this if the region is not young
4489 // (since we don't refine cards in young regions).
4490 if (!skip_hot_card_cache && !hr->is_young()) {
4491 _hot_card_cache->reset_card_counts(hr);
4492 }
4493 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4494 free_list->add_ordered(hr);
4495 }
4496
4497 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4498 FreeRegionList* free_list,
4499 bool skip_remset) {
4500 assert(hr->is_humongous(), "this is only for humongous regions");
4501 assert(free_list != NULL, "pre-condition");
4502 hr->clear_humongous();
4503 free_region(hr, free_list, skip_remset);
4504 }
4505
4506 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4507 const uint humongous_regions_removed) {
4508 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4509 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4510 _old_set.bulk_remove(old_regions_removed);
4511 _humongous_set.bulk_remove(humongous_regions_removed);
4512 }
4513
4514 }
4515
4516 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4517 assert(list != NULL, "list can't be null");
4518 if (!list->is_empty()) {
4519 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4520 _hrm.insert_list_into_free_list(list);
4521 }
4522 }
4523
4524 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4525 decrease_used(bytes);
4526 }
4527
4528 class G1ParScrubRemSetTask: public AbstractGangTask {
4529 protected:
4530 G1RemSet* _g1rs;
4531 HeapRegionClaimer _hrclaimer;
4532
4533 public:
4534 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4535 AbstractGangTask("G1 ScrubRS"),
4536 _g1rs(g1_rs),
4537 _hrclaimer(num_workers) {
4538 }
4539
4540 void work(uint worker_id) {
4541 _g1rs->scrub(worker_id, &_hrclaimer);
4542 }
4543 };
4544
4545 void G1CollectedHeap::scrub_rem_set() {
4546 uint num_workers = workers()->active_workers();
4547 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4548 workers()->run_task(&g1_par_scrub_rs_task);
4549 }
4550
4551 class G1FreeCollectionSetTask : public AbstractGangTask {
4552 private:
4553
4554 // Closure applied to all regions in the collection set to do work that needs to
4555 // be done serially in a single thread.
4556 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4557 private:
4558 EvacuationInfo* _evacuation_info;
4559 const size_t* _surviving_young_words;
4560
4561 // Bytes used in successfully evacuated regions before the evacuation.
4562 size_t _before_used_bytes;
4563 // Bytes used in unsucessfully evacuated regions before the evacuation
4564 size_t _after_used_bytes;
4565
4566 size_t _bytes_allocated_in_old_since_last_gc;
4567
4568 size_t _failure_used_words;
4569 size_t _failure_waste_words;
4570
4571 FreeRegionList _local_free_list;
4572 public:
4573 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4574 HeapRegionClosure(),
4575 _evacuation_info(evacuation_info),
4576 _surviving_young_words(surviving_young_words),
4577 _before_used_bytes(0),
4578 _after_used_bytes(0),
4579 _bytes_allocated_in_old_since_last_gc(0),
4580 _failure_used_words(0),
4581 _failure_waste_words(0),
4582 _local_free_list("Local Region List for CSet Freeing") {
4583 }
4584
4585 virtual bool doHeapRegion(HeapRegion* r) {
4586 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4587
4588 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4589 g1h->clear_in_cset(r);
4590
4591 if (r->is_young()) {
4592 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4593 "Young index %d is wrong for region %u of type %s with %u young regions",
4594 r->young_index_in_cset(),
4595 r->hrm_index(),
4596 r->get_type_str(),
4597 g1h->collection_set()->young_region_length());
4598 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4599 r->record_surv_words_in_group(words_survived);
4600 }
4601
4602 if (!r->evacuation_failed()) {
4603 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4604 _before_used_bytes += r->used();
4605 g1h->free_region(r,
4606 &_local_free_list,
4607 true, /* skip_remset */
4608 true, /* skip_hot_card_cache */
4609 true /* locked */);
4610 } else {
4611 r->uninstall_surv_rate_group();
4612 r->set_young_index_in_cset(-1);
4613 r->set_evacuation_failed(false);
4614 // When moving a young gen region to old gen, we "allocate" that whole region
4615 // there. This is in addition to any already evacuated objects. Notify the
4616 // policy about that.
4617 // Old gen regions do not cause an additional allocation: both the objects
4618 // still in the region and the ones already moved are accounted for elsewhere.
4619 if (r->is_young()) {
4620 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4621 }
4622 // The region is now considered to be old.
4623 r->set_old();
4624 // Do some allocation statistics accounting. Regions that failed evacuation
4625 // are always made old, so there is no need to update anything in the young
4626 // gen statistics, but we need to update old gen statistics.
4627 size_t used_words = r->marked_bytes() / HeapWordSize;
4628
4629 _failure_used_words += used_words;
4630 _failure_waste_words += HeapRegion::GrainWords - used_words;
4631
4632 g1h->old_set_add(r);
4633 _after_used_bytes += r->used();
4634 }
4635 return false;
4636 }
4637
4638 void complete_work() {
4639 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4640
4641 _evacuation_info->set_regions_freed(_local_free_list.length());
4642 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4643
4644 g1h->prepend_to_freelist(&_local_free_list);
4645 g1h->decrement_summary_bytes(_before_used_bytes);
4646
4647 G1Policy* policy = g1h->g1_policy();
4648 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4649
4650 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4651 }
4652 };
4653
4654 G1CollectionSet* _collection_set;
4655 G1SerialFreeCollectionSetClosure _cl;
4656 const size_t* _surviving_young_words;
4657
4658 size_t _rs_lengths;
4659
4660 volatile jint _serial_work_claim;
4661
4662 struct WorkItem {
4663 uint region_idx;
4664 bool is_young;
4665 bool evacuation_failed;
4666
4667 WorkItem(HeapRegion* r) {
4668 region_idx = r->hrm_index();
4669 is_young = r->is_young();
4670 evacuation_failed = r->evacuation_failed();
4671 }
4672 };
4673
4674 volatile size_t _parallel_work_claim;
4675 size_t _num_work_items;
4676 WorkItem* _work_items;
4677
4678 void do_serial_work() {
4679 // Need to grab the lock to be allowed to modify the old region list.
4680 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4681 _collection_set->iterate(&_cl);
4682 }
4683
4684 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4685 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4686
4687 HeapRegion* r = g1h->region_at(region_idx);
4688 assert(!g1h->is_on_master_free_list(r), "sanity");
4689
4690 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4691
4692 if (!is_young) {
4693 g1h->_hot_card_cache->reset_card_counts(r);
4694 }
4695
4696 if (!evacuation_failed) {
4697 r->rem_set()->clear_locked();
4698 }
4699 }
4700
4701 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4702 private:
4703 size_t _cur_idx;
4704 WorkItem* _work_items;
4705 public:
4706 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4707
4708 virtual bool doHeapRegion(HeapRegion* r) {
4709 _work_items[_cur_idx++] = WorkItem(r);
4710 return false;
4711 }
4712 };
4713
4714 void prepare_work() {
4715 G1PrepareFreeCollectionSetClosure cl(_work_items);
4716 _collection_set->iterate(&cl);
4717 }
4718
4719 void complete_work() {
4720 _cl.complete_work();
4721
4722 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4723 policy->record_max_rs_lengths(_rs_lengths);
4724 policy->cset_regions_freed();
4725 }
4726 public:
4727 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4728 AbstractGangTask("G1 Free Collection Set"),
4729 _cl(evacuation_info, surviving_young_words),
4730 _collection_set(collection_set),
4731 _surviving_young_words(surviving_young_words),
4732 _serial_work_claim(0),
4733 _rs_lengths(0),
4734 _parallel_work_claim(0),
4735 _num_work_items(collection_set->region_length()),
4736 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4737 prepare_work();
4738 }
4739
4740 ~G1FreeCollectionSetTask() {
4741 complete_work();
4742 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4743 }
4744
4745 // Chunk size for work distribution. The chosen value has been determined experimentally
4746 // to be a good tradeoff between overhead and achievable parallelism.
4747 static uint chunk_size() { return 32; }
4748
4749 virtual void work(uint worker_id) {
4750 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4751
4752 // Claim serial work.
4753 if (_serial_work_claim == 0) {
4754 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4755 if (value == 0) {
4756 double serial_time = os::elapsedTime();
4757 do_serial_work();
4758 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4759 }
4760 }
4761
4762 // Start parallel work.
4763 double young_time = 0.0;
4764 bool has_young_time = false;
4765 double non_young_time = 0.0;
4766 bool has_non_young_time = false;
4767
4768 while (true) {
4769 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4770 size_t cur = end - chunk_size();
4771
4772 if (cur >= _num_work_items) {
4773 break;
4774 }
4775
4776 double start_time = os::elapsedTime();
4777
4778 end = MIN2(end, _num_work_items);
4779
4780 for (; cur < end; cur++) {
4781 bool is_young = _work_items[cur].is_young;
4782
4783 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4784
4785 double end_time = os::elapsedTime();
4786 double time_taken = end_time - start_time;
4787 if (is_young) {
4788 young_time += time_taken;
4789 has_young_time = true;
4790 } else {
4791 non_young_time += time_taken;
4792 has_non_young_time = true;
4793 }
4794 start_time = end_time;
4795 }
4796 }
4797
4798 if (has_young_time) {
4799 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4800 }
4801 if (has_non_young_time) {
4802 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4803 }
4804 }
4805 };
4806
4807 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4808 _eden.clear();
4809
4810 double free_cset_start_time = os::elapsedTime();
4811
4812 {
4813 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4814 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4815
4816 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4817
4818 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4819 cl.name(),
4820 num_workers,
4821 _collection_set.region_length());
4822 workers()->run_task(&cl, num_workers);
4823 }
4824 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4825
4826 collection_set->clear();
4827 }
4828
4829 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4830 private:
4831 FreeRegionList* _free_region_list;
4832 HeapRegionSet* _proxy_set;
4833 uint _humongous_objects_reclaimed;
4834 uint _humongous_regions_reclaimed;
4835 size_t _freed_bytes;
4836 public:
4837
4838 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4839 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4840 }
4841
4842 virtual bool doHeapRegion(HeapRegion* r) {
4843 if (!r->is_starts_humongous()) {
4844 return false;
4845 }
4846
4847 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4848
4849 oop obj = (oop)r->bottom();
4850 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4851
4852 // The following checks whether the humongous object is live are sufficient.
4853 // The main additional check (in addition to having a reference from the roots
4854 // or the young gen) is whether the humongous object has a remembered set entry.
4855 //
4856 // A humongous object cannot be live if there is no remembered set for it
4857 // because:
4858 // - there can be no references from within humongous starts regions referencing
4859 // the object because we never allocate other objects into them.
4860 // (I.e. there are no intra-region references that may be missed by the
4861 // remembered set)
4862 // - as soon there is a remembered set entry to the humongous starts region
4863 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4864 // until the end of a concurrent mark.
4865 //
4866 // It is not required to check whether the object has been found dead by marking
4867 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4868 // all objects allocated during that time are considered live.
4869 // SATB marking is even more conservative than the remembered set.
4870 // So if at this point in the collection there is no remembered set entry,
4871 // nobody has a reference to it.
4872 // At the start of collection we flush all refinement logs, and remembered sets
4873 // are completely up-to-date wrt to references to the humongous object.
4874 //
4875 // Other implementation considerations:
4876 // - never consider object arrays at this time because they would pose
4877 // considerable effort for cleaning up the the remembered sets. This is
4878 // required because stale remembered sets might reference locations that
4879 // are currently allocated into.
4880 uint region_idx = r->hrm_index();
4881 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4882 !r->rem_set()->is_empty()) {
4883 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4884 region_idx,
4885 (size_t)obj->size() * HeapWordSize,
4886 p2i(r->bottom()),
4887 r->rem_set()->occupied(),
4888 r->rem_set()->strong_code_roots_list_length(),
4889 next_bitmap->isMarked(r->bottom()),
4890 g1h->is_humongous_reclaim_candidate(region_idx),
4891 obj->is_typeArray()
4892 );
4893 return false;
4894 }
4895
4896 guarantee(obj->is_typeArray(),
4897 "Only eagerly reclaiming type arrays is supported, but the object "
4898 PTR_FORMAT " is not.", p2i(r->bottom()));
4899
4900 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4901 region_idx,
4902 (size_t)obj->size() * HeapWordSize,
4903 p2i(r->bottom()),
4904 r->rem_set()->occupied(),
4905 r->rem_set()->strong_code_roots_list_length(),
4906 next_bitmap->isMarked(r->bottom()),
4907 g1h->is_humongous_reclaim_candidate(region_idx),
4908 obj->is_typeArray()
4909 );
4910
4911 // Need to clear mark bit of the humongous object if already set.
4912 if (next_bitmap->isMarked(r->bottom())) {
4913 next_bitmap->clear(r->bottom());
4914 }
4915 _humongous_objects_reclaimed++;
4916 do {
4917 HeapRegion* next = g1h->next_region_in_humongous(r);
4918 _freed_bytes += r->used();
4919 r->set_containing_set(NULL);
4920 _humongous_regions_reclaimed++;
4921 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4922 r = next;
4923 } while (r != NULL);
4924
4925 return false;
4926 }
4927
4928 uint humongous_objects_reclaimed() {
4929 return _humongous_objects_reclaimed;
4930 }
4931
4932 uint humongous_regions_reclaimed() {
4933 return _humongous_regions_reclaimed;
4934 }
4935
4936 size_t bytes_freed() const {
4937 return _freed_bytes;
4938 }
4939 };
4940
4941 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4942 assert_at_safepoint(true);
4943
4944 if (!G1EagerReclaimHumongousObjects ||
4945 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4946 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4947 return;
4948 }
4949
4950 double start_time = os::elapsedTime();
4951
4952 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4953
4954 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4955 heap_region_iterate(&cl);
4956
4957 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4958
4959 G1HRPrinter* hrp = hr_printer();
4960 if (hrp->is_active()) {
4961 FreeRegionListIterator iter(&local_cleanup_list);
4962 while (iter.more_available()) {
4963 HeapRegion* hr = iter.get_next();
4964 hrp->cleanup(hr);
4965 }
4966 }
4967
4968 prepend_to_freelist(&local_cleanup_list);
4969 decrement_summary_bytes(cl.bytes_freed());
4970
4971 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4972 cl.humongous_objects_reclaimed());
4973 }
4974
4975 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4976 public:
4977 virtual bool doHeapRegion(HeapRegion* r) {
4978 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4979 G1CollectedHeap::heap()->clear_in_cset(r);
4980 r->set_young_index_in_cset(-1);
4981 return false;
4982 }
4983 };
4984
4985 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4986 G1AbandonCollectionSetClosure cl;
4987 collection_set->iterate(&cl);
4988
4989 collection_set->clear();
4990 collection_set->stop_incremental_building();
4991 }
4992
4993 void G1CollectedHeap::set_free_regions_coming() {
4994 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4995
4996 assert(!free_regions_coming(), "pre-condition");
4997 _free_regions_coming = true;
4998 }
4999
5000 void G1CollectedHeap::reset_free_regions_coming() {
5001 assert(free_regions_coming(), "pre-condition");
5002
5003 {
5004 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5005 _free_regions_coming = false;
5006 SecondaryFreeList_lock->notify_all();
5007 }
5008
5009 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5010 }
5011
5012 void G1CollectedHeap::wait_while_free_regions_coming() {
5013 // Most of the time we won't have to wait, so let's do a quick test
5014 // first before we take the lock.
5015 if (!free_regions_coming()) {
5016 return;
5017 }
5018
5019 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5020
5021 {
5022 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5023 while (free_regions_coming()) {
5024 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5025 }
5026 }
5027
5028 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5029 }
5030
5031 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5032 return _allocator->is_retained_old_region(hr);
5033 }
5034
5035 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5036 _eden.add(hr);
5037 _g1_policy->set_region_eden(hr);
5038 }
5039
5040 #ifdef ASSERT
5041
5042 class NoYoungRegionsClosure: public HeapRegionClosure {
5043 private:
5044 bool _success;
5045 public:
5046 NoYoungRegionsClosure() : _success(true) { }
5047 bool doHeapRegion(HeapRegion* r) {
5048 if (r->is_young()) {
5049 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5050 p2i(r->bottom()), p2i(r->end()));
5051 _success = false;
5052 }
5053 return false;
5054 }
5055 bool success() { return _success; }
5056 };
5057
5058 bool G1CollectedHeap::check_young_list_empty() {
5059 bool ret = (young_regions_count() == 0);
5060
5061 NoYoungRegionsClosure closure;
5062 heap_region_iterate(&closure);
5063 ret = ret && closure.success();
5064
5065 return ret;
5066 }
5067
5068 #endif // ASSERT
5069
5070 class TearDownRegionSetsClosure : public HeapRegionClosure {
5071 private:
5072 HeapRegionSet *_old_set;
5073
5074 public:
5075 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5076
5077 bool doHeapRegion(HeapRegion* r) {
5078 if (r->is_old()) {
5079 _old_set->remove(r);
5080 } else if(r->is_young()) {
5081 r->uninstall_surv_rate_group();
5082 } else {
5083 // We ignore free regions, we'll empty the free list afterwards.
5084 // We ignore humongous regions, we're not tearing down the
5085 // humongous regions set.
5086 assert(r->is_free() || r->is_humongous(),
5087 "it cannot be another type");
5088 }
5089 return false;
5090 }
5091
5092 ~TearDownRegionSetsClosure() {
5093 assert(_old_set->is_empty(), "post-condition");
5094 }
5095 };
5096
5097 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5098 assert_at_safepoint(true /* should_be_vm_thread */);
5099
5100 if (!free_list_only) {
5101 TearDownRegionSetsClosure cl(&_old_set);
5102 heap_region_iterate(&cl);
5103
5104 // Note that emptying the _young_list is postponed and instead done as
5105 // the first step when rebuilding the regions sets again. The reason for
5106 // this is that during a full GC string deduplication needs to know if
5107 // a collected region was young or old when the full GC was initiated.
5108 }
5109 _hrm.remove_all_free_regions();
5110 }
5111
5112 void G1CollectedHeap::increase_used(size_t bytes) {
5113 _summary_bytes_used += bytes;
5114 }
5115
5116 void G1CollectedHeap::decrease_used(size_t bytes) {
5117 assert(_summary_bytes_used >= bytes,
5118 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5119 _summary_bytes_used, bytes);
5120 _summary_bytes_used -= bytes;
5121 }
5122
5123 void G1CollectedHeap::set_used(size_t bytes) {
5124 _summary_bytes_used = bytes;
5125 }
5126
5127 class RebuildRegionSetsClosure : public HeapRegionClosure {
5128 private:
5129 bool _free_list_only;
5130 HeapRegionSet* _old_set;
5131 HeapRegionManager* _hrm;
5132 size_t _total_used;
5133
5134 public:
5135 RebuildRegionSetsClosure(bool free_list_only,
5136 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5137 _free_list_only(free_list_only),
5138 _old_set(old_set), _hrm(hrm), _total_used(0) {
5139 assert(_hrm->num_free_regions() == 0, "pre-condition");
5140 if (!free_list_only) {
5141 assert(_old_set->is_empty(), "pre-condition");
5142 }
5143 }
5144
5145 bool doHeapRegion(HeapRegion* r) {
5146 if (r->is_empty()) {
5147 // Add free regions to the free list
5148 r->set_free();
5149 r->set_allocation_context(AllocationContext::system());
5150 _hrm->insert_into_free_list(r);
5151 } else if (!_free_list_only) {
5152
5153 if (r->is_humongous()) {
5154 // We ignore humongous regions. We left the humongous set unchanged.
5155 } else {
5156 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5157 // We now consider all regions old, so register as such. Leave
5158 // archive regions set that way, however, while still adding
5159 // them to the old set.
5160 if (!r->is_archive()) {
5161 r->set_old();
5162 }
5163 _old_set->add(r);
5164 }
5165 _total_used += r->used();
5166 }
5167
5168 return false;
5169 }
5170
5171 size_t total_used() {
5172 return _total_used;
5173 }
5174 };
5175
5176 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5177 assert_at_safepoint(true /* should_be_vm_thread */);
5178
5179 if (!free_list_only) {
5180 _eden.clear();
5181 _survivor.clear();
5182 }
5183
5184 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5185 heap_region_iterate(&cl);
5186
5187 if (!free_list_only) {
5188 set_used(cl.total_used());
5189 if (_archive_allocator != NULL) {
5190 _archive_allocator->clear_used();
5191 }
5192 }
5193 assert(used_unlocked() == recalculate_used(),
5194 "inconsistent used_unlocked(), "
5195 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5196 used_unlocked(), recalculate_used());
5197 }
5198
5199 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5200 _refine_cte_cl->set_concurrent(concurrent);
5201 }
5202
5203 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5204 HeapRegion* hr = heap_region_containing(p);
5205 return hr->is_in(p);
5206 }
5207
5208 // Methods for the mutator alloc region
5209
5210 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5211 bool force) {
5212 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5213 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5214 if (force || should_allocate) {
5215 HeapRegion* new_alloc_region = new_region(word_size,
5216 false /* is_old */,
5217 false /* do_expand */);
5218 if (new_alloc_region != NULL) {
5219 set_region_short_lived_locked(new_alloc_region);
5220 _hr_printer.alloc(new_alloc_region, !should_allocate);
5221 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5222 return new_alloc_region;
5223 }
5224 }
5225 return NULL;
5226 }
5227
5228 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5229 size_t allocated_bytes) {
5230 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5231 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5232
5233 collection_set()->add_eden_region(alloc_region);
5234 increase_used(allocated_bytes);
5235 _hr_printer.retire(alloc_region);
5236 // We update the eden sizes here, when the region is retired,
5237 // instead of when it's allocated, since this is the point that its
5238 // used space has been recored in _summary_bytes_used.
5239 g1mm()->update_eden_size();
5240 }
5241
5242 // Methods for the GC alloc regions
5243
5244 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5245 if (dest.is_old()) {
5246 return true;
5247 } else {
5248 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5249 }
5250 }
5251
5252 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5253 assert(FreeList_lock->owned_by_self(), "pre-condition");
5254
5255 if (!has_more_regions(dest)) {
5256 return NULL;
5257 }
5258
5259 const bool is_survivor = dest.is_young();
5260
5261 HeapRegion* new_alloc_region = new_region(word_size,
5262 !is_survivor,
5263 true /* do_expand */);
5264 if (new_alloc_region != NULL) {
5265 // We really only need to do this for old regions given that we
5266 // should never scan survivors. But it doesn't hurt to do it
5267 // for survivors too.
5268 new_alloc_region->record_timestamp();
5269 if (is_survivor) {
5270 new_alloc_region->set_survivor();
5271 _survivor.add(new_alloc_region);
5272 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5273 } else {
5274 new_alloc_region->set_old();
5275 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5276 }
5277 _hr_printer.alloc(new_alloc_region);
5278 bool during_im = collector_state()->during_initial_mark_pause();
5279 new_alloc_region->note_start_of_copying(during_im);
5280 return new_alloc_region;
5281 }
5282 return NULL;
5283 }
5284
5285 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5286 size_t allocated_bytes,
5287 InCSetState dest) {
5288 bool during_im = collector_state()->during_initial_mark_pause();
5289 alloc_region->note_end_of_copying(during_im);
5290 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5291 if (dest.is_old()) {
5292 _old_set.add(alloc_region);
5293 }
5294 _hr_printer.retire(alloc_region);
5295 }
5296
5297 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5298 bool expanded = false;
5299 uint index = _hrm.find_highest_free(&expanded);
5300
5301 if (index != G1_NO_HRM_INDEX) {
5302 if (expanded) {
5303 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5304 HeapRegion::GrainWords * HeapWordSize);
5305 }
5306 _hrm.allocate_free_regions_starting_at(index, 1);
5307 return region_at(index);
5308 }
5309 return NULL;
5310 }
5311
5312 // Optimized nmethod scanning
5313
5314 class RegisterNMethodOopClosure: public OopClosure {
5315 G1CollectedHeap* _g1h;
5316 nmethod* _nm;
5317
5318 template <class T> void do_oop_work(T* p) {
5319 T heap_oop = oopDesc::load_heap_oop(p);
5320 if (!oopDesc::is_null(heap_oop)) {
5321 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5322 HeapRegion* hr = _g1h->heap_region_containing(obj);
5323 assert(!hr->is_continues_humongous(),
5324 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5325 " starting at " HR_FORMAT,
5326 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5327
5328 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5329 hr->add_strong_code_root_locked(_nm);
5330 }
5331 }
5332
5333 public:
5334 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5335 _g1h(g1h), _nm(nm) {}
5336
5337 void do_oop(oop* p) { do_oop_work(p); }
5338 void do_oop(narrowOop* p) { do_oop_work(p); }
5339 };
5340
5341 class UnregisterNMethodOopClosure: public OopClosure {
5342 G1CollectedHeap* _g1h;
5343 nmethod* _nm;
5344
5345 template <class T> void do_oop_work(T* p) {
5346 T heap_oop = oopDesc::load_heap_oop(p);
5347 if (!oopDesc::is_null(heap_oop)) {
5348 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5349 HeapRegion* hr = _g1h->heap_region_containing(obj);
5350 assert(!hr->is_continues_humongous(),
5351 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5352 " starting at " HR_FORMAT,
5353 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5354
5355 hr->remove_strong_code_root(_nm);
5356 }
5357 }
5358
5359 public:
5360 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5361 _g1h(g1h), _nm(nm) {}
5362
5363 void do_oop(oop* p) { do_oop_work(p); }
5364 void do_oop(narrowOop* p) { do_oop_work(p); }
5365 };
5366
5367 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5368 CollectedHeap::register_nmethod(nm);
5369
5370 guarantee(nm != NULL, "sanity");
5371 RegisterNMethodOopClosure reg_cl(this, nm);
5372 nm->oops_do(®_cl);
5373 }
5374
5375 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5376 CollectedHeap::unregister_nmethod(nm);
5377
5378 guarantee(nm != NULL, "sanity");
5379 UnregisterNMethodOopClosure reg_cl(this, nm);
5380 nm->oops_do(®_cl, true);
5381 }
5382
5383 void G1CollectedHeap::purge_code_root_memory() {
5384 double purge_start = os::elapsedTime();
5385 G1CodeRootSet::purge();
5386 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5387 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5388 }
5389
5390 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5391 G1CollectedHeap* _g1h;
5392
5393 public:
5394 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5395 _g1h(g1h) {}
5396
5397 void do_code_blob(CodeBlob* cb) {
5398 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5399 if (nm == NULL) {
5400 return;
5401 }
5402
5403 if (ScavengeRootsInCode) {
5404 _g1h->register_nmethod(nm);
5405 }
5406 }
5407 };
5408
5409 void G1CollectedHeap::rebuild_strong_code_roots() {
5410 RebuildStrongCodeRootClosure blob_cl(this);
5411 CodeCache::blobs_do(&blob_cl);
5412 }