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/g1FullCollector.hpp"
42 #include "gc/g1/g1FullGCScope.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.inline.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.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/align.hpp"
84 #include "utilities/globalDefinitions.hpp"
85 #include "utilities/stack.inline.hpp"
86
87 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
88
89 // INVARIANTS/NOTES
90 //
91 // All allocation activity covered by the G1CollectedHeap interface is
92 // serialized by acquiring the HeapLock. This happens in mem_allocate
93 // and allocate_new_tlab, which are the "entry" points to the
94 // allocation code from the rest of the JVM. (Note that this does not
95 // apply to TLAB allocation, which is not part of this interface: it
96 // is done by clients of this interface.)
97
98 // Local to this file.
99
100 class RefineCardTableEntryClosure: public CardTableEntryClosure {
101 bool _concurrent;
102 public:
103 RefineCardTableEntryClosure() : _concurrent(true) { }
104
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
107
108 if (_concurrent && SuspendibleThreadSet::should_yield()) {
109 // Caller will actually yield.
110 return false;
111 }
112 // Otherwise, we finished successfully; return true.
113 return true;
114 }
115
116 void set_concurrent(bool b) { _concurrent = b; }
117 };
118
119
120 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
121 private:
122 size_t _num_dirtied;
123 G1CollectedHeap* _g1h;
124 G1SATBCardTableLoggingModRefBS* _g1_bs;
125
126 HeapRegion* region_for_card(jbyte* card_ptr) const {
127 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
128 }
129
130 bool will_become_free(HeapRegion* hr) const {
131 // A region will be freed by free_collection_set if the region is in the
132 // collection set and has not had an evacuation failure.
133 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
134 }
135
136 public:
137 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
138 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
139
140 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
141 HeapRegion* hr = region_for_card(card_ptr);
142
143 // Should only dirty cards in regions that won't be freed.
144 if (!will_become_free(hr)) {
145 *card_ptr = CardTableModRefBS::dirty_card_val();
146 _num_dirtied++;
147 }
148
149 return true;
150 }
151
152 size_t num_dirtied() const { return _num_dirtied; }
153 };
154
155
156 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
157 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
158 }
159
160 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
161 // The from card cache is not the memory that is actually committed. So we cannot
162 // take advantage of the zero_filled parameter.
163 reset_from_card_cache(start_idx, num_regions);
164 }
165
166 // Returns true if the reference points to an object that
167 // can move in an incremental collection.
168 bool G1CollectedHeap::is_scavengable(const void* p) {
169 HeapRegion* hr = heap_region_containing(p);
170 return !hr->is_pinned();
171 }
172
173
174 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
175 MemRegion mr) {
176 return new HeapRegion(hrs_index, bot(), mr);
177 }
178
179 // Private methods.
180
181 HeapRegion*
182 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
183 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
184 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
185 if (!_secondary_free_list.is_empty()) {
186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
187 "secondary_free_list has %u entries",
188 _secondary_free_list.length());
189 // It looks as if there are free regions available on the
190 // secondary_free_list. Let's move them to the free_list and try
191 // again to allocate from it.
192 append_secondary_free_list();
193
194 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
195 "empty we should have moved at least one entry to the free_list");
196 HeapRegion* res = _hrm.allocate_free_region(is_old);
197 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
198 "allocated " HR_FORMAT " from secondary_free_list",
199 HR_FORMAT_PARAMS(res));
200 return res;
201 }
202
203 // Wait here until we get notified either when (a) there are no
204 // more free regions coming or (b) some regions have been moved on
205 // the secondary_free_list.
206 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
207 }
208
209 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
210 "could not allocate from secondary_free_list");
211 return NULL;
212 }
213
214 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
215 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
216 "the only time we use this to allocate a humongous region is "
217 "when we are allocating a single humongous region");
218
219 HeapRegion* res;
220 if (G1StressConcRegionFreeing) {
221 if (!_secondary_free_list.is_empty()) {
222 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
223 "forced to look at the secondary_free_list");
224 res = new_region_try_secondary_free_list(is_old);
225 if (res != NULL) {
226 return res;
227 }
228 }
229 }
230
231 res = _hrm.allocate_free_region(is_old);
232
233 if (res == NULL) {
234 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
235 "res == NULL, trying the secondary_free_list");
236 res = new_region_try_secondary_free_list(is_old);
237 }
238 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
239 // Currently, only attempts to allocate GC alloc regions set
240 // do_expand to true. So, we should only reach here during a
241 // safepoint. If this assumption changes we might have to
242 // reconsider the use of _expand_heap_after_alloc_failure.
243 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
244
245 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
246 word_size * HeapWordSize);
247
248 if (expand(word_size * HeapWordSize)) {
249 // Given that expand() succeeded in expanding the heap, and we
250 // always expand the heap by an amount aligned to the heap
251 // region size, the free list should in theory not be empty.
252 // In either case allocate_free_region() will check for NULL.
253 res = _hrm.allocate_free_region(is_old);
254 } else {
255 _expand_heap_after_alloc_failure = false;
256 }
257 }
258 return res;
259 }
260
261 HeapWord*
262 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
263 uint num_regions,
264 size_t word_size,
265 AllocationContext_t context) {
266 assert(first != G1_NO_HRM_INDEX, "pre-condition");
267 assert(is_humongous(word_size), "word_size should be humongous");
268 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
269
270 // Index of last region in the series.
271 uint last = first + num_regions - 1;
272
273 // We need to initialize the region(s) we just discovered. This is
274 // a bit tricky given that it can happen concurrently with
275 // refinement threads refining cards on these regions and
276 // potentially wanting to refine the BOT as they are scanning
277 // those cards (this can happen shortly after a cleanup; see CR
278 // 6991377). So we have to set up the region(s) carefully and in
279 // a specific order.
280
281 // The word size sum of all the regions we will allocate.
282 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
283 assert(word_size <= word_size_sum, "sanity");
284
285 // This will be the "starts humongous" region.
286 HeapRegion* first_hr = region_at(first);
287 // The header of the new object will be placed at the bottom of
288 // the first region.
289 HeapWord* new_obj = first_hr->bottom();
290 // This will be the new top of the new object.
291 HeapWord* obj_top = new_obj + word_size;
292
293 // First, we need to zero the header of the space that we will be
294 // allocating. When we update top further down, some refinement
295 // threads might try to scan the region. By zeroing the header we
296 // ensure that any thread that will try to scan the region will
297 // come across the zero klass word and bail out.
298 //
299 // NOTE: It would not have been correct to have used
300 // CollectedHeap::fill_with_object() and make the space look like
301 // an int array. The thread that is doing the allocation will
302 // later update the object header to a potentially different array
303 // type and, for a very short period of time, the klass and length
304 // fields will be inconsistent. This could cause a refinement
305 // thread to calculate the object size incorrectly.
306 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
307
308 // Next, pad out the unused tail of the last region with filler
309 // objects, for improved usage accounting.
310 // How many words we use for filler objects.
311 size_t word_fill_size = word_size_sum - word_size;
312
313 // How many words memory we "waste" which cannot hold a filler object.
314 size_t words_not_fillable = 0;
315
316 if (word_fill_size >= min_fill_size()) {
317 fill_with_objects(obj_top, word_fill_size);
318 } else if (word_fill_size > 0) {
319 // We have space to fill, but we cannot fit an object there.
320 words_not_fillable = word_fill_size;
321 word_fill_size = 0;
322 }
323
324 // We will set up the first region as "starts humongous". This
325 // will also update the BOT covering all the regions to reflect
326 // that there is a single object that starts at the bottom of the
327 // first region.
328 first_hr->set_starts_humongous(obj_top, word_fill_size);
329 first_hr->set_allocation_context(context);
330 // Then, if there are any, we will set up the "continues
331 // humongous" regions.
332 HeapRegion* hr = NULL;
333 for (uint i = first + 1; i <= last; ++i) {
334 hr = region_at(i);
335 hr->set_continues_humongous(first_hr);
336 hr->set_allocation_context(context);
337 }
338
339 // Up to this point no concurrent thread would have been able to
340 // do any scanning on any region in this series. All the top
341 // fields still point to bottom, so the intersection between
342 // [bottom,top] and [card_start,card_end] will be empty. Before we
343 // update the top fields, we'll do a storestore to make sure that
344 // no thread sees the update to top before the zeroing of the
345 // object header and the BOT initialization.
346 OrderAccess::storestore();
347
348 // Now, we will update the top fields of the "continues humongous"
349 // regions except the last one.
350 for (uint i = first; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_top(hr->end());
353 }
354
355 hr = region_at(last);
356 // If we cannot fit a filler object, we must set top to the end
357 // of the humongous object, otherwise we cannot iterate the heap
358 // and the BOT will not be complete.
359 hr->set_top(hr->end() - words_not_fillable);
360
361 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
362 "obj_top should be in last region");
363
364 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
365
366 assert(words_not_fillable == 0 ||
367 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
368 "Miscalculation in humongous allocation");
369
370 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
371
372 for (uint i = first; i <= last; ++i) {
373 hr = region_at(i);
374 _humongous_set.add(hr);
375 _hr_printer.alloc(hr);
376 }
377
378 return new_obj;
379 }
380
381 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
382 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
383 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
384 }
385
386 // If could fit into free regions w/o expansion, try.
387 // Otherwise, if can expand, do so.
388 // Otherwise, if using ex regions might help, try with ex given back.
389 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
390 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
391
392 _verifier->verify_region_sets_optional();
393
394 uint first = G1_NO_HRM_INDEX;
395 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
396
397 if (obj_regions == 1) {
398 // Only one region to allocate, try to use a fast path by directly allocating
399 // from the free lists. Do not try to expand here, we will potentially do that
400 // later.
401 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
402 if (hr != NULL) {
403 first = hr->hrm_index();
404 }
405 } else {
406 // We can't allocate humongous regions spanning more than one region while
407 // cleanupComplete() is running, since some of the regions we find to be
408 // empty might not yet be added to the free list. It is not straightforward
409 // to know in which list they are on so that we can remove them. We only
410 // need to do this if we need to allocate more than one region to satisfy the
411 // current humongous allocation request. If we are only allocating one region
412 // we use the one-region region allocation code (see above), that already
413 // potentially waits for regions from the secondary free list.
414 wait_while_free_regions_coming();
415 append_secondary_free_list_if_not_empty_with_lock();
416
417 // Policy: Try only empty regions (i.e. already committed first). Maybe we
418 // are lucky enough to find some.
419 first = _hrm.find_contiguous_only_empty(obj_regions);
420 if (first != G1_NO_HRM_INDEX) {
421 _hrm.allocate_free_regions_starting_at(first, obj_regions);
422 }
423 }
424
425 if (first == G1_NO_HRM_INDEX) {
426 // Policy: We could not find enough regions for the humongous object in the
427 // free list. Look through the heap to find a mix of free and uncommitted regions.
428 // If so, try expansion.
429 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
430 if (first != G1_NO_HRM_INDEX) {
431 // We found something. Make sure these regions are committed, i.e. expand
432 // the heap. Alternatively we could do a defragmentation GC.
433 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
434 word_size * HeapWordSize);
435
436 _hrm.expand_at(first, obj_regions, workers());
437 g1_policy()->record_new_heap_size(num_regions());
438
439 #ifdef ASSERT
440 for (uint i = first; i < first + obj_regions; ++i) {
441 HeapRegion* hr = region_at(i);
442 assert(hr->is_free(), "sanity");
443 assert(hr->is_empty(), "sanity");
444 assert(is_on_master_free_list(hr), "sanity");
445 }
446 #endif
447 _hrm.allocate_free_regions_starting_at(first, obj_regions);
448 } else {
449 // Policy: Potentially trigger a defragmentation GC.
450 }
451 }
452
453 HeapWord* result = NULL;
454 if (first != G1_NO_HRM_INDEX) {
455 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
456 word_size, context);
457 assert(result != NULL, "it should always return a valid result");
458
459 // A successful humongous object allocation changes the used space
460 // information of the old generation so we need to recalculate the
461 // sizes and update the jstat counters here.
462 g1mm()->update_sizes();
463 }
464
465 _verifier->verify_region_sets_optional();
466
467 return result;
468 }
469
470 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
471 assert_heap_not_locked_and_not_at_safepoint();
472 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
473
474 uint dummy_gc_count_before;
475 uint dummy_gclocker_retry_count = 0;
476 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
477 }
478
479 HeapWord*
480 G1CollectedHeap::mem_allocate(size_t word_size,
481 bool* gc_overhead_limit_was_exceeded) {
482 assert_heap_not_locked_and_not_at_safepoint();
483
484 // Loop until the allocation is satisfied, or unsatisfied after GC.
485 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
486 uint gc_count_before;
487
488 HeapWord* result = NULL;
489 if (!is_humongous(word_size)) {
490 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
491 } else {
492 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
493 }
494 if (result != NULL) {
495 return result;
496 }
497
498 // Create the garbage collection operation...
499 VM_G1CollectForAllocation op(gc_count_before, word_size);
500 op.set_allocation_context(AllocationContext::current());
501
502 // ...and get the VM thread to execute it.
503 VMThread::execute(&op);
504
505 if (op.prologue_succeeded() && op.pause_succeeded()) {
506 // If the operation was successful we'll return the result even
507 // if it is NULL. If the allocation attempt failed immediately
508 // after a Full GC, it's unlikely we'll be able to allocate now.
509 HeapWord* result = op.result();
510 if (result != NULL && !is_humongous(word_size)) {
511 // Allocations that take place on VM operations do not do any
512 // card dirtying and we have to do it here. We only have to do
513 // this for non-humongous allocations, though.
514 dirty_young_block(result, word_size);
515 }
516 return result;
517 } else {
518 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
519 return NULL;
520 }
521 assert(op.result() == NULL,
522 "the result should be NULL if the VM op did not succeed");
523 }
524
525 // Give a warning if we seem to be looping forever.
526 if ((QueuedAllocationWarningCount > 0) &&
527 (try_count % QueuedAllocationWarningCount == 0)) {
528 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
529 }
530 }
531
532 ShouldNotReachHere();
533 return NULL;
534 }
535
536 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
537 AllocationContext_t context,
538 uint* gc_count_before_ret,
539 uint* gclocker_retry_count_ret) {
540 // Make sure you read the note in attempt_allocation_humongous().
541
542 assert_heap_not_locked_and_not_at_safepoint();
543 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
544 "be called for humongous allocation requests");
545
546 // We should only get here after the first-level allocation attempt
547 // (attempt_allocation()) failed to allocate.
548
549 // We will loop until a) we manage to successfully perform the
550 // allocation or b) we successfully schedule a collection which
551 // fails to perform the allocation. b) is the only case when we'll
552 // return NULL.
553 HeapWord* result = NULL;
554 for (int try_count = 1; /* we'll return */; try_count += 1) {
555 bool should_try_gc;
556 uint gc_count_before;
557
558 {
559 MutexLockerEx x(Heap_lock);
560 result = _allocator->attempt_allocation_locked(word_size, context);
561 if (result != NULL) {
562 return result;
563 }
564
565 if (GCLocker::is_active_and_needs_gc()) {
566 if (g1_policy()->can_expand_young_list()) {
567 // No need for an ergo verbose message here,
568 // can_expand_young_list() does this when it returns true.
569 result = _allocator->attempt_allocation_force(word_size, context);
570 if (result != NULL) {
571 return result;
572 }
573 }
574 should_try_gc = false;
575 } else {
576 // The GCLocker may not be active but the GCLocker initiated
577 // GC may not yet have been performed (GCLocker::needs_gc()
578 // returns true). In this case we do not try this GC and
579 // wait until the GCLocker initiated GC is performed, and
580 // then retry the allocation.
581 if (GCLocker::needs_gc()) {
582 should_try_gc = false;
583 } else {
584 // Read the GC count while still holding the Heap_lock.
585 gc_count_before = total_collections();
586 should_try_gc = true;
587 }
588 }
589 }
590
591 if (should_try_gc) {
592 bool succeeded;
593 result = do_collection_pause(word_size, gc_count_before, &succeeded,
594 GCCause::_g1_inc_collection_pause);
595 if (result != NULL) {
596 assert(succeeded, "only way to get back a non-NULL result");
597 return result;
598 }
599
600 if (succeeded) {
601 // If we get here we successfully scheduled a collection which
602 // failed to allocate. No point in trying to allocate
603 // further. We'll just return NULL.
604 MutexLockerEx x(Heap_lock);
605 *gc_count_before_ret = total_collections();
606 return NULL;
607 }
608 } else {
609 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
610 MutexLockerEx x(Heap_lock);
611 *gc_count_before_ret = total_collections();
612 return NULL;
613 }
614 // The GCLocker is either active or the GCLocker initiated
615 // GC has not yet been performed. Stall until it is and
616 // then retry the allocation.
617 GCLocker::stall_until_clear();
618 (*gclocker_retry_count_ret) += 1;
619 }
620
621 // We can reach here if we were unsuccessful in scheduling a
622 // collection (because another thread beat us to it) or if we were
623 // stalled due to the GC locker. In either can we should retry the
624 // allocation attempt in case another thread successfully
625 // performed a collection and reclaimed enough space. We do the
626 // first attempt (without holding the Heap_lock) here and the
627 // follow-on attempt will be at the start of the next loop
628 // iteration (after taking the Heap_lock).
629 result = _allocator->attempt_allocation(word_size, context);
630 if (result != NULL) {
631 return result;
632 }
633
634 // Give a warning if we seem to be looping forever.
635 if ((QueuedAllocationWarningCount > 0) &&
636 (try_count % QueuedAllocationWarningCount == 0)) {
637 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
638 "retries %d times", try_count);
639 }
640 }
641
642 ShouldNotReachHere();
643 return NULL;
644 }
645
646 void G1CollectedHeap::begin_archive_alloc_range() {
647 assert_at_safepoint(true /* should_be_vm_thread */);
648 if (_archive_allocator == NULL) {
649 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
650 }
651 }
652
653 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
654 // Allocations in archive regions cannot be of a size that would be considered
655 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
656 // may be different at archive-restore time.
657 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
658 }
659
660 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
661 assert_at_safepoint(true /* should_be_vm_thread */);
662 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
663 if (is_archive_alloc_too_large(word_size)) {
664 return NULL;
665 }
666 return _archive_allocator->archive_mem_allocate(word_size);
667 }
668
669 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
670 size_t end_alignment_in_bytes) {
671 assert_at_safepoint(true /* should_be_vm_thread */);
672 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
673
674 // Call complete_archive to do the real work, filling in the MemRegion
675 // array with the archive regions.
676 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
677 delete _archive_allocator;
678 _archive_allocator = NULL;
679 }
680
681 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
682 assert(ranges != NULL, "MemRegion array NULL");
683 assert(count != 0, "No MemRegions provided");
684 MemRegion reserved = _hrm.reserved();
685 for (size_t i = 0; i < count; i++) {
686 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
687 return false;
688 }
689 }
690 return true;
691 }
692
693 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
694 assert(!is_init_completed(), "Expect to be called at JVM init time");
695 assert(ranges != NULL, "MemRegion array NULL");
696 assert(count != 0, "No MemRegions provided");
697 MutexLockerEx x(Heap_lock);
698
699 MemRegion reserved = _hrm.reserved();
700 HeapWord* prev_last_addr = NULL;
701 HeapRegion* prev_last_region = NULL;
702
703 // Temporarily disable pretouching of heap pages. This interface is used
704 // when mmap'ing archived heap data in, so pre-touching is wasted.
705 FlagSetting fs(AlwaysPreTouch, false);
706
707 // Enable archive object checking used by G1MarkSweep. We have to let it know
708 // about each archive range, so that objects in those ranges aren't marked.
709 G1ArchiveAllocator::enable_archive_object_check();
710
711 // For each specified MemRegion range, allocate the corresponding G1
712 // regions and mark them as archive regions. We expect the ranges in
713 // ascending starting address order, without overlap.
714 for (size_t i = 0; i < count; i++) {
715 MemRegion curr_range = ranges[i];
716 HeapWord* start_address = curr_range.start();
717 size_t word_size = curr_range.word_size();
718 HeapWord* last_address = curr_range.last();
719 size_t commits = 0;
720
721 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
722 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
723 p2i(start_address), p2i(last_address));
724 guarantee(start_address > prev_last_addr,
725 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
726 p2i(start_address), p2i(prev_last_addr));
727 prev_last_addr = last_address;
728
729 // Check for ranges that start in the same G1 region in which the previous
730 // range ended, and adjust the start address so we don't try to allocate
731 // the same region again. If the current range is entirely within that
732 // region, skip it, just adjusting the recorded top.
733 HeapRegion* start_region = _hrm.addr_to_region(start_address);
734 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
735 start_address = start_region->end();
736 if (start_address > last_address) {
737 increase_used(word_size * HeapWordSize);
738 start_region->set_top(last_address + 1);
739 continue;
740 }
741 start_region->set_top(start_address);
742 curr_range = MemRegion(start_address, last_address + 1);
743 start_region = _hrm.addr_to_region(start_address);
744 }
745
746 // Perform the actual region allocation, exiting if it fails.
747 // Then note how much new space we have allocated.
748 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
749 return false;
750 }
751 increase_used(word_size * HeapWordSize);
752 if (commits != 0) {
753 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
754 HeapRegion::GrainWords * HeapWordSize * commits);
755
756 }
757
758 // Mark each G1 region touched by the range as archive, add it to the old set,
759 // and set the allocation context and top.
760 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
761 HeapRegion* last_region = _hrm.addr_to_region(last_address);
762 prev_last_region = last_region;
763
764 while (curr_region != NULL) {
765 assert(curr_region->is_empty() && !curr_region->is_pinned(),
766 "Region already in use (index %u)", curr_region->hrm_index());
767 curr_region->set_allocation_context(AllocationContext::system());
768 curr_region->set_archive();
769 _hr_printer.alloc(curr_region);
770 _old_set.add(curr_region);
771 if (curr_region != last_region) {
772 curr_region->set_top(curr_region->end());
773 curr_region = _hrm.next_region_in_heap(curr_region);
774 } else {
775 curr_region->set_top(last_address + 1);
776 curr_region = NULL;
777 }
778 }
779
780 // Notify mark-sweep of the archive range.
781 G1ArchiveAllocator::set_range_archive(curr_range, true);
782 }
783 return true;
784 }
785
786 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
787 assert(!is_init_completed(), "Expect to be called at JVM init time");
788 assert(ranges != NULL, "MemRegion array NULL");
789 assert(count != 0, "No MemRegions provided");
790 MemRegion reserved = _hrm.reserved();
791 HeapWord *prev_last_addr = NULL;
792 HeapRegion* prev_last_region = NULL;
793
794 // For each MemRegion, create filler objects, if needed, in the G1 regions
795 // that contain the address range. The address range actually within the
796 // MemRegion will not be modified. That is assumed to have been initialized
797 // elsewhere, probably via an mmap of archived heap data.
798 MutexLockerEx x(Heap_lock);
799 for (size_t i = 0; i < count; i++) {
800 HeapWord* start_address = ranges[i].start();
801 HeapWord* last_address = ranges[i].last();
802
803 assert(reserved.contains(start_address) && reserved.contains(last_address),
804 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
805 p2i(start_address), p2i(last_address));
806 assert(start_address > prev_last_addr,
807 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
808 p2i(start_address), p2i(prev_last_addr));
809
810 HeapRegion* start_region = _hrm.addr_to_region(start_address);
811 HeapRegion* last_region = _hrm.addr_to_region(last_address);
812 HeapWord* bottom_address = start_region->bottom();
813
814 // Check for a range beginning in the same region in which the
815 // previous one ended.
816 if (start_region == prev_last_region) {
817 bottom_address = prev_last_addr + 1;
818 }
819
820 // Verify that the regions were all marked as archive regions by
821 // alloc_archive_regions.
822 HeapRegion* curr_region = start_region;
823 while (curr_region != NULL) {
824 guarantee(curr_region->is_archive(),
825 "Expected archive region at index %u", curr_region->hrm_index());
826 if (curr_region != last_region) {
827 curr_region = _hrm.next_region_in_heap(curr_region);
828 } else {
829 curr_region = NULL;
830 }
831 }
832
833 prev_last_addr = last_address;
834 prev_last_region = last_region;
835
836 // Fill the memory below the allocated range with dummy object(s),
837 // if the region bottom does not match the range start, or if the previous
838 // range ended within the same G1 region, and there is a gap.
839 if (start_address != bottom_address) {
840 size_t fill_size = pointer_delta(start_address, bottom_address);
841 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
842 increase_used(fill_size * HeapWordSize);
843 }
844 }
845 }
846
847 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
848 uint* gc_count_before_ret,
849 uint* gclocker_retry_count_ret) {
850 assert_heap_not_locked_and_not_at_safepoint();
851 assert(!is_humongous(word_size), "attempt_allocation() should not "
852 "be called for humongous allocation requests");
853
854 AllocationContext_t context = AllocationContext::current();
855 HeapWord* result = _allocator->attempt_allocation(word_size, context);
856
857 if (result == NULL) {
858 result = attempt_allocation_slow(word_size,
859 context,
860 gc_count_before_ret,
861 gclocker_retry_count_ret);
862 }
863 assert_heap_not_locked();
864 if (result != NULL) {
865 dirty_young_block(result, word_size);
866 }
867 return result;
868 }
869
870 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
871 assert(!is_init_completed(), "Expect to be called at JVM init time");
872 assert(ranges != NULL, "MemRegion array NULL");
873 assert(count != 0, "No MemRegions provided");
874 MemRegion reserved = _hrm.reserved();
875 HeapWord* prev_last_addr = NULL;
876 HeapRegion* prev_last_region = NULL;
877 size_t size_used = 0;
878 size_t uncommitted_regions = 0;
879
880 // For each Memregion, free the G1 regions that constitute it, and
881 // notify mark-sweep that the range is no longer to be considered 'archive.'
882 MutexLockerEx x(Heap_lock);
883 for (size_t i = 0; i < count; i++) {
884 HeapWord* start_address = ranges[i].start();
885 HeapWord* last_address = ranges[i].last();
886
887 assert(reserved.contains(start_address) && reserved.contains(last_address),
888 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
889 p2i(start_address), p2i(last_address));
890 assert(start_address > prev_last_addr,
891 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
892 p2i(start_address), p2i(prev_last_addr));
893 size_used += ranges[i].byte_size();
894 prev_last_addr = last_address;
895
896 HeapRegion* start_region = _hrm.addr_to_region(start_address);
897 HeapRegion* last_region = _hrm.addr_to_region(last_address);
898
899 // Check for ranges that start in the same G1 region in which the previous
900 // range ended, and adjust the start address so we don't try to free
901 // the same region again. If the current range is entirely within that
902 // region, skip it.
903 if (start_region == prev_last_region) {
904 start_address = start_region->end();
905 if (start_address > last_address) {
906 continue;
907 }
908 start_region = _hrm.addr_to_region(start_address);
909 }
910 prev_last_region = last_region;
911
912 // After verifying that each region was marked as an archive region by
913 // alloc_archive_regions, set it free and empty and uncommit it.
914 HeapRegion* curr_region = start_region;
915 while (curr_region != NULL) {
916 guarantee(curr_region->is_archive(),
917 "Expected archive region at index %u", curr_region->hrm_index());
918 uint curr_index = curr_region->hrm_index();
919 _old_set.remove(curr_region);
920 curr_region->set_free();
921 curr_region->set_top(curr_region->bottom());
922 if (curr_region != last_region) {
923 curr_region = _hrm.next_region_in_heap(curr_region);
924 } else {
925 curr_region = NULL;
926 }
927 _hrm.shrink_at(curr_index, 1);
928 uncommitted_regions++;
929 }
930
931 // Notify mark-sweep that this is no longer an archive range.
932 G1ArchiveAllocator::set_range_archive(ranges[i], false);
933 }
934
935 if (uncommitted_regions != 0) {
936 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
937 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
938 }
939 decrease_used(size_used);
940 }
941
942 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
943 uint* gc_count_before_ret,
944 uint* gclocker_retry_count_ret) {
945 // The structure of this method has a lot of similarities to
946 // attempt_allocation_slow(). The reason these two were not merged
947 // into a single one is that such a method would require several "if
948 // allocation is not humongous do this, otherwise do that"
949 // conditional paths which would obscure its flow. In fact, an early
950 // version of this code did use a unified method which was harder to
951 // follow and, as a result, it had subtle bugs that were hard to
952 // track down. So keeping these two methods separate allows each to
953 // be more readable. It will be good to keep these two in sync as
954 // much as possible.
955
956 assert_heap_not_locked_and_not_at_safepoint();
957 assert(is_humongous(word_size), "attempt_allocation_humongous() "
958 "should only be called for humongous allocations");
959
960 // Humongous objects can exhaust the heap quickly, so we should check if we
961 // need to start a marking cycle at each humongous object allocation. We do
962 // the check before we do the actual allocation. The reason for doing it
963 // before the allocation is that we avoid having to keep track of the newly
964 // allocated memory while we do a GC.
965 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
966 word_size)) {
967 collect(GCCause::_g1_humongous_allocation);
968 }
969
970 // We will loop until a) we manage to successfully perform the
971 // allocation or b) we successfully schedule a collection which
972 // fails to perform the allocation. b) is the only case when we'll
973 // return NULL.
974 HeapWord* result = NULL;
975 for (int try_count = 1; /* we'll return */; try_count += 1) {
976 bool should_try_gc;
977 uint gc_count_before;
978
979 {
980 MutexLockerEx x(Heap_lock);
981
982 // Given that humongous objects are not allocated in young
983 // regions, we'll first try to do the allocation without doing a
984 // collection hoping that there's enough space in the heap.
985 result = humongous_obj_allocate(word_size, AllocationContext::current());
986 if (result != NULL) {
987 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
988 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
989 return result;
990 }
991
992 if (GCLocker::is_active_and_needs_gc()) {
993 should_try_gc = false;
994 } else {
995 // The GCLocker may not be active but the GCLocker initiated
996 // GC may not yet have been performed (GCLocker::needs_gc()
997 // returns true). In this case we do not try this GC and
998 // wait until the GCLocker initiated GC is performed, and
999 // then retry the allocation.
1000 if (GCLocker::needs_gc()) {
1001 should_try_gc = false;
1002 } else {
1003 // Read the GC count while still holding the Heap_lock.
1004 gc_count_before = total_collections();
1005 should_try_gc = true;
1006 }
1007 }
1008 }
1009
1010 if (should_try_gc) {
1011 // If we failed to allocate the humongous object, we should try to
1012 // do a collection pause (if we're allowed) in case it reclaims
1013 // enough space for the allocation to succeed after the pause.
1014
1015 bool succeeded;
1016 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1017 GCCause::_g1_humongous_allocation);
1018 if (result != NULL) {
1019 assert(succeeded, "only way to get back a non-NULL result");
1020 return result;
1021 }
1022
1023 if (succeeded) {
1024 // If we get here we successfully scheduled a collection which
1025 // failed to allocate. No point in trying to allocate
1026 // further. We'll just return NULL.
1027 MutexLockerEx x(Heap_lock);
1028 *gc_count_before_ret = total_collections();
1029 return NULL;
1030 }
1031 } else {
1032 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1033 MutexLockerEx x(Heap_lock);
1034 *gc_count_before_ret = total_collections();
1035 return NULL;
1036 }
1037 // The GCLocker is either active or the GCLocker initiated
1038 // GC has not yet been performed. Stall until it is and
1039 // then retry the allocation.
1040 GCLocker::stall_until_clear();
1041 (*gclocker_retry_count_ret) += 1;
1042 }
1043
1044 // We can reach here if we were unsuccessful in scheduling a
1045 // collection (because another thread beat us to it) or if we were
1046 // stalled due to the GC locker. In either can we should retry the
1047 // allocation attempt in case another thread successfully
1048 // performed a collection and reclaimed enough space. Give a
1049 // warning if we seem to be looping forever.
1050
1051 if ((QueuedAllocationWarningCount > 0) &&
1052 (try_count % QueuedAllocationWarningCount == 0)) {
1053 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1054 "retries %d times", try_count);
1055 }
1056 }
1057
1058 ShouldNotReachHere();
1059 return NULL;
1060 }
1061
1062 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1063 AllocationContext_t context,
1064 bool expect_null_mutator_alloc_region) {
1065 assert_at_safepoint(true /* should_be_vm_thread */);
1066 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1067 "the current alloc region was unexpectedly found to be non-NULL");
1068
1069 if (!is_humongous(word_size)) {
1070 return _allocator->attempt_allocation_locked(word_size, context);
1071 } else {
1072 HeapWord* result = humongous_obj_allocate(word_size, context);
1073 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1074 collector_state()->set_initiate_conc_mark_if_possible(true);
1075 }
1076 return result;
1077 }
1078
1079 ShouldNotReachHere();
1080 }
1081
1082 class PostCompactionPrinterClosure: public HeapRegionClosure {
1083 private:
1084 G1HRPrinter* _hr_printer;
1085 public:
1086 bool doHeapRegion(HeapRegion* hr) {
1087 assert(!hr->is_young(), "not expecting to find young regions");
1088 _hr_printer->post_compaction(hr);
1089 return false;
1090 }
1091
1092 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1093 : _hr_printer(hr_printer) { }
1094 };
1095
1096 void G1CollectedHeap::print_hrm_post_compaction() {
1097 if (_hr_printer.is_active()) {
1098 PostCompactionPrinterClosure cl(hr_printer());
1099 heap_region_iterate(&cl);
1100 }
1101
1102 }
1103
1104 void G1CollectedHeap::abort_concurrent_cycle() {
1105 // Note: When we have a more flexible GC logging framework that
1106 // allows us to add optional attributes to a GC log record we
1107 // could consider timing and reporting how long we wait in the
1108 // following two methods.
1109 wait_while_free_regions_coming();
1110 // If we start the compaction before the CM threads finish
1111 // scanning the root regions we might trip them over as we'll
1112 // be moving objects / updating references. So let's wait until
1113 // they are done. By telling them to abort, they should complete
1114 // early.
1115 _cm->root_regions()->abort();
1116 _cm->root_regions()->wait_until_scan_finished();
1117 append_secondary_free_list_if_not_empty_with_lock();
1118
1119 // Disable discovery and empty the discovered lists
1120 // for the CM ref processor.
1121 ref_processor_cm()->disable_discovery();
1122 ref_processor_cm()->abandon_partial_discovery();
1123 ref_processor_cm()->verify_no_references_recorded();
1124
1125 // Abandon current iterations of concurrent marking and concurrent
1126 // refinement, if any are in progress.
1127 concurrent_mark()->abort();
1128 }
1129
1130 void G1CollectedHeap::prepare_heap_for_full_collection() {
1131 // Make sure we'll choose a new allocation region afterwards.
1132 _allocator->release_mutator_alloc_region();
1133 _allocator->abandon_gc_alloc_regions();
1134 g1_rem_set()->cleanupHRRS();
1135
1136 // We may have added regions to the current incremental collection
1137 // set between the last GC or pause and now. We need to clear the
1138 // incremental collection set and then start rebuilding it afresh
1139 // after this full GC.
1140 abandon_collection_set(collection_set());
1141
1142 tear_down_region_sets(false /* free_list_only */);
1143 collector_state()->set_gcs_are_young(true);
1144 }
1145
1146 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1147 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1148 assert(used() == recalculate_used(), "Should be equal");
1149 _verifier->verify_region_sets_optional();
1150 _verifier->verify_before_gc();
1151 _verifier->check_bitmaps("Full GC Start");
1152 }
1153
1154 void G1CollectedHeap::prepare_heap_for_mutators() {
1155 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1156 ClassLoaderDataGraph::purge();
1157 MetaspaceAux::verify_metrics();
1158
1159 // Prepare heap for normal collections.
1160 assert(num_free_regions() == 0, "we should not have added any free regions");
1161 rebuild_region_sets(false /* free_list_only */);
1162 abort_refinement();
1163 resize_if_necessary_after_full_collection();
1164
1165 // Rebuild the strong code root lists for each region
1166 rebuild_strong_code_roots();
1167
1168 // Start a new incremental collection set for the next pause
1169 start_new_collection_set();
1170
1171 _allocator->init_mutator_alloc_region();
1172
1173 // Post collection state updates.
1174 MetaspaceGC::compute_new_size();
1175 }
1176
1177 void G1CollectedHeap::abort_refinement() {
1178 if (_hot_card_cache->use_cache()) {
1179 _hot_card_cache->reset_card_counts();
1180 _hot_card_cache->reset_hot_cache();
1181 }
1182
1183 // Discard all remembered set updates.
1184 JavaThread::dirty_card_queue_set().abandon_logs();
1185 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1186 }
1187
1188 void G1CollectedHeap::verify_after_full_collection() {
1189 check_gc_time_stamps();
1190 _hrm.verify_optional();
1191 _verifier->verify_region_sets_optional();
1192 _verifier->verify_after_gc();
1193 // Clear the previous marking bitmap, if needed for bitmap verification.
1194 // Note we cannot do this when we clear the next marking bitmap in
1195 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1196 // objects marked during a full GC against the previous bitmap.
1197 // But we need to clear it before calling check_bitmaps below since
1198 // the full GC has compacted objects and updated TAMS but not updated
1199 // the prev bitmap.
1200 if (G1VerifyBitmaps) {
1201 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1202 _cm->clear_prev_bitmap(workers());
1203 }
1204 _verifier->check_bitmaps("Full GC End");
1205
1206 // At this point there should be no regions in the
1207 // entire heap tagged as young.
1208 assert(check_young_list_empty(), "young list should be empty at this point");
1209
1210 // Note: since we've just done a full GC, concurrent
1211 // marking is no longer active. Therefore we need not
1212 // re-enable reference discovery for the CM ref processor.
1213 // That will be done at the start of the next marking cycle.
1214 // We also know that the STW processor should no longer
1215 // discover any new references.
1216 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1217 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1218 ref_processor_stw()->verify_no_references_recorded();
1219 ref_processor_cm()->verify_no_references_recorded();
1220 }
1221
1222 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1223 print_hrm_post_compaction();
1224 heap_transition->print();
1225 print_heap_after_gc();
1226 print_heap_regions();
1227 #ifdef TRACESPINNING
1228 ParallelTaskTerminator::print_termination_counts();
1229 #endif
1230 }
1231
1232 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1233 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1234 g1_policy()->record_full_collection_start();
1235
1236 print_heap_before_gc();
1237 print_heap_regions();
1238
1239 abort_concurrent_cycle();
1240 verify_before_full_collection(scope->is_explicit_gc());
1241
1242 gc_prologue(true);
1243 prepare_heap_for_full_collection();
1244
1245 {
1246 G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->nextMarkBitMap(), workers()->active_workers());
1247 // Prepare collection by putting reference processor
1248 // in a correct state.
1249 collector.prepare_collection();
1250
1251 // Do the actual collection.
1252 collector.collect();
1253
1254 collector.complete_collection();
1255 }
1256
1257 prepare_heap_for_mutators();
1258
1259 g1_policy()->record_full_collection_end();
1260 gc_epilogue(true);
1261
1262 // Post collection verification.
1263 verify_after_full_collection();
1264
1265 // Post collection logging.
1266 // We should do this after we potentially resize the heap so
1267 // that all the COMMIT / UNCOMMIT events are generated before
1268 // the compaction events.
1269 print_heap_after_full_collection(scope->heap_transition());
1270 }
1271 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1272 bool clear_all_soft_refs) {
1273 assert_at_safepoint(true /* should_be_vm_thread */);
1274
1275 if (GCLocker::check_active_before_gc()) {
1276 // Full GC was not completed.
1277 return false;
1278 }
1279
1280 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1281 collector_policy()->should_clear_all_soft_refs();
1282
1283 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1284 do_full_collection_inner(&scope);
1285
1286 // Full collection was successfully completed.
1287 return true;
1288 }
1289
1290 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1291 // Currently, there is no facility in the do_full_collection(bool) API to notify
1292 // the caller that the collection did not succeed (e.g., because it was locked
1293 // out by the GC locker). So, right now, we'll ignore the return value.
1294 bool dummy = do_full_collection(true, /* explicit_gc */
1295 clear_all_soft_refs);
1296 }
1297
1298 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1299 // Include bytes that will be pre-allocated to support collections, as "used".
1300 const size_t used_after_gc = used();
1301 const size_t capacity_after_gc = capacity();
1302 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1303
1304 // This is enforced in arguments.cpp.
1305 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1306 "otherwise the code below doesn't make sense");
1307
1308 // We don't have floating point command-line arguments
1309 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1310 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1311 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1312 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1313
1314 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1315 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1316
1317 // We have to be careful here as these two calculations can overflow
1318 // 32-bit size_t's.
1319 double used_after_gc_d = (double) used_after_gc;
1320 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1321 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1322
1323 // Let's make sure that they are both under the max heap size, which
1324 // by default will make them fit into a size_t.
1325 double desired_capacity_upper_bound = (double) max_heap_size;
1326 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1327 desired_capacity_upper_bound);
1328 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1329 desired_capacity_upper_bound);
1330
1331 // We can now safely turn them into size_t's.
1332 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1333 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1334
1335 // This assert only makes sense here, before we adjust them
1336 // with respect to the min and max heap size.
1337 assert(minimum_desired_capacity <= maximum_desired_capacity,
1338 "minimum_desired_capacity = " SIZE_FORMAT ", "
1339 "maximum_desired_capacity = " SIZE_FORMAT,
1340 minimum_desired_capacity, maximum_desired_capacity);
1341
1342 // Should not be greater than the heap max size. No need to adjust
1343 // it with respect to the heap min size as it's a lower bound (i.e.,
1344 // we'll try to make the capacity larger than it, not smaller).
1345 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1346 // Should not be less than the heap min size. No need to adjust it
1347 // with respect to the heap max size as it's an upper bound (i.e.,
1348 // we'll try to make the capacity smaller than it, not greater).
1349 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1350
1351 if (capacity_after_gc < minimum_desired_capacity) {
1352 // Don't expand unless it's significant
1353 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1354
1355 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1356 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1357 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1358
1359 expand(expand_bytes, _workers);
1360
1361 // No expansion, now see if we want to shrink
1362 } else if (capacity_after_gc > maximum_desired_capacity) {
1363 // Capacity too large, compute shrinking size
1364 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1365
1366 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1367 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1368 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1369
1370 shrink(shrink_bytes);
1371 }
1372 }
1373
1374 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1375 AllocationContext_t context,
1376 bool do_gc,
1377 bool clear_all_soft_refs,
1378 bool expect_null_mutator_alloc_region,
1379 bool* gc_succeeded) {
1380 *gc_succeeded = true;
1381 // Let's attempt the allocation first.
1382 HeapWord* result =
1383 attempt_allocation_at_safepoint(word_size,
1384 context,
1385 expect_null_mutator_alloc_region);
1386 if (result != NULL) {
1387 assert(*gc_succeeded, "sanity");
1388 return result;
1389 }
1390
1391 // In a G1 heap, we're supposed to keep allocation from failing by
1392 // incremental pauses. Therefore, at least for now, we'll favor
1393 // expansion over collection. (This might change in the future if we can
1394 // do something smarter than full collection to satisfy a failed alloc.)
1395 result = expand_and_allocate(word_size, context);
1396 if (result != NULL) {
1397 assert(*gc_succeeded, "sanity");
1398 return result;
1399 }
1400
1401 if (do_gc) {
1402 // Expansion didn't work, we'll try to do a Full GC.
1403 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1404 clear_all_soft_refs);
1405 }
1406
1407 return NULL;
1408 }
1409
1410 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1411 AllocationContext_t context,
1412 bool* succeeded) {
1413 assert_at_safepoint(true /* should_be_vm_thread */);
1414
1415 // Attempts to allocate followed by Full GC.
1416 HeapWord* result =
1417 satisfy_failed_allocation_helper(word_size,
1418 context,
1419 true, /* do_gc */
1420 false, /* clear_all_soft_refs */
1421 false, /* expect_null_mutator_alloc_region */
1422 succeeded);
1423
1424 if (result != NULL || !*succeeded) {
1425 return result;
1426 }
1427
1428 // Attempts to allocate followed by Full GC that will collect all soft references.
1429 result = satisfy_failed_allocation_helper(word_size,
1430 context,
1431 true, /* do_gc */
1432 true, /* clear_all_soft_refs */
1433 true, /* expect_null_mutator_alloc_region */
1434 succeeded);
1435
1436 if (result != NULL || !*succeeded) {
1437 return result;
1438 }
1439
1440 // Attempts to allocate, no GC
1441 result = satisfy_failed_allocation_helper(word_size,
1442 context,
1443 false, /* do_gc */
1444 false, /* clear_all_soft_refs */
1445 true, /* expect_null_mutator_alloc_region */
1446 succeeded);
1447
1448 if (result != NULL) {
1449 assert(*succeeded, "sanity");
1450 return result;
1451 }
1452
1453 assert(!collector_policy()->should_clear_all_soft_refs(),
1454 "Flag should have been handled and cleared prior to this point");
1455
1456 // What else? We might try synchronous finalization later. If the total
1457 // space available is large enough for the allocation, then a more
1458 // complete compaction phase than we've tried so far might be
1459 // appropriate.
1460 assert(*succeeded, "sanity");
1461 return NULL;
1462 }
1463
1464 // Attempting to expand the heap sufficiently
1465 // to support an allocation of the given "word_size". If
1466 // successful, perform the allocation and return the address of the
1467 // allocated block, or else "NULL".
1468
1469 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1470 assert_at_safepoint(true /* should_be_vm_thread */);
1471
1472 _verifier->verify_region_sets_optional();
1473
1474 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1475 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1476 word_size * HeapWordSize);
1477
1478
1479 if (expand(expand_bytes, _workers)) {
1480 _hrm.verify_optional();
1481 _verifier->verify_region_sets_optional();
1482 return attempt_allocation_at_safepoint(word_size,
1483 context,
1484 false /* expect_null_mutator_alloc_region */);
1485 }
1486 return NULL;
1487 }
1488
1489 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1490 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1491 aligned_expand_bytes = align_up(aligned_expand_bytes,
1492 HeapRegion::GrainBytes);
1493
1494 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1495 expand_bytes, aligned_expand_bytes);
1496
1497 if (is_maximal_no_gc()) {
1498 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1499 return false;
1500 }
1501
1502 double expand_heap_start_time_sec = os::elapsedTime();
1503 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1504 assert(regions_to_expand > 0, "Must expand by at least one region");
1505
1506 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1507 if (expand_time_ms != NULL) {
1508 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1509 }
1510
1511 if (expanded_by > 0) {
1512 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1513 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1514 g1_policy()->record_new_heap_size(num_regions());
1515 } else {
1516 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1517
1518 // The expansion of the virtual storage space was unsuccessful.
1519 // Let's see if it was because we ran out of swap.
1520 if (G1ExitOnExpansionFailure &&
1521 _hrm.available() >= regions_to_expand) {
1522 // We had head room...
1523 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1524 }
1525 }
1526 return regions_to_expand > 0;
1527 }
1528
1529 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1530 size_t aligned_shrink_bytes =
1531 ReservedSpace::page_align_size_down(shrink_bytes);
1532 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1533 HeapRegion::GrainBytes);
1534 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1535
1536 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1537 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1538
1539
1540 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",
1541 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1542 if (num_regions_removed > 0) {
1543 g1_policy()->record_new_heap_size(num_regions());
1544 } else {
1545 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1546 }
1547 }
1548
1549 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1550 _verifier->verify_region_sets_optional();
1551
1552 // We should only reach here at the end of a Full GC which means we
1553 // should not not be holding to any GC alloc regions. The method
1554 // below will make sure of that and do any remaining clean up.
1555 _allocator->abandon_gc_alloc_regions();
1556
1557 // Instead of tearing down / rebuilding the free lists here, we
1558 // could instead use the remove_all_pending() method on free_list to
1559 // remove only the ones that we need to remove.
1560 tear_down_region_sets(true /* free_list_only */);
1561 shrink_helper(shrink_bytes);
1562 rebuild_region_sets(true /* free_list_only */);
1563
1564 _hrm.verify_optional();
1565 _verifier->verify_region_sets_optional();
1566 }
1567
1568 // Public methods.
1569
1570 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1571 CollectedHeap(),
1572 _collector_policy(collector_policy),
1573 _g1_policy(create_g1_policy()),
1574 _collection_set(this, _g1_policy),
1575 _dirty_card_queue_set(false),
1576 _is_alive_closure_cm(this),
1577 _is_alive_closure_stw(this),
1578 _ref_processor_cm(NULL),
1579 _ref_processor_stw(NULL),
1580 _bot(NULL),
1581 _hot_card_cache(NULL),
1582 _g1_rem_set(NULL),
1583 _cg1r(NULL),
1584 _g1mm(NULL),
1585 _refine_cte_cl(NULL),
1586 _preserved_marks_set(true /* in_c_heap */),
1587 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1588 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1589 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1590 _humongous_reclaim_candidates(),
1591 _has_humongous_reclaim_candidates(false),
1592 _archive_allocator(NULL),
1593 _free_regions_coming(false),
1594 _gc_time_stamp(0),
1595 _summary_bytes_used(0),
1596 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1597 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1598 _expand_heap_after_alloc_failure(true),
1599 _old_marking_cycles_started(0),
1600 _old_marking_cycles_completed(0),
1601 _in_cset_fast_test(),
1602 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1603 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1604
1605 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1606 /* are_GC_task_threads */true,
1607 /* are_ConcurrentGC_threads */false);
1608 _workers->initialize_workers();
1609 _verifier = new G1HeapVerifier(this);
1610
1611 _allocator = G1Allocator::create_allocator(this);
1612
1613 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1614
1615 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1616
1617 // Override the default _filler_array_max_size so that no humongous filler
1618 // objects are created.
1619 _filler_array_max_size = _humongous_object_threshold_in_words;
1620
1621 uint n_queues = ParallelGCThreads;
1622 _task_queues = new RefToScanQueueSet(n_queues);
1623
1624 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1625
1626 for (uint i = 0; i < n_queues; i++) {
1627 RefToScanQueue* q = new RefToScanQueue();
1628 q->initialize();
1629 _task_queues->register_queue(i, q);
1630 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1631 }
1632
1633 // Initialize the G1EvacuationFailureALot counters and flags.
1634 NOT_PRODUCT(reset_evacuation_should_fail();)
1635
1636 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1637 }
1638
1639 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1640 size_t size,
1641 size_t translation_factor) {
1642 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1643 // Allocate a new reserved space, preferring to use large pages.
1644 ReservedSpace rs(size, preferred_page_size);
1645 G1RegionToSpaceMapper* result =
1646 G1RegionToSpaceMapper::create_mapper(rs,
1647 size,
1648 rs.alignment(),
1649 HeapRegion::GrainBytes,
1650 translation_factor,
1651 mtGC);
1652
1653 os::trace_page_sizes_for_requested_size(description,
1654 size,
1655 preferred_page_size,
1656 rs.alignment(),
1657 rs.base(),
1658 rs.size());
1659
1660 return result;
1661 }
1662
1663 jint G1CollectedHeap::initialize() {
1664 CollectedHeap::pre_initialize();
1665 os::enable_vtime();
1666
1667 // Necessary to satisfy locking discipline assertions.
1668
1669 MutexLocker x(Heap_lock);
1670
1671 // While there are no constraints in the GC code that HeapWordSize
1672 // be any particular value, there are multiple other areas in the
1673 // system which believe this to be true (e.g. oop->object_size in some
1674 // cases incorrectly returns the size in wordSize units rather than
1675 // HeapWordSize).
1676 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1677
1678 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1679 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1680 size_t heap_alignment = collector_policy()->heap_alignment();
1681
1682 // Ensure that the sizes are properly aligned.
1683 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1684 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1685 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1686
1687 _refine_cte_cl = new RefineCardTableEntryClosure();
1688
1689 jint ecode = JNI_OK;
1690 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1691 if (_cg1r == NULL) {
1692 return ecode;
1693 }
1694
1695 // Reserve the maximum.
1696
1697 // When compressed oops are enabled, the preferred heap base
1698 // is calculated by subtracting the requested size from the
1699 // 32Gb boundary and using the result as the base address for
1700 // heap reservation. If the requested size is not aligned to
1701 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1702 // into the ReservedHeapSpace constructor) then the actual
1703 // base of the reserved heap may end up differing from the
1704 // address that was requested (i.e. the preferred heap base).
1705 // If this happens then we could end up using a non-optimal
1706 // compressed oops mode.
1707
1708 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1709 heap_alignment);
1710
1711 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1712
1713 // Create the barrier set for the entire reserved region.
1714 G1SATBCardTableLoggingModRefBS* bs
1715 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1716 bs->initialize();
1717 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1718 set_barrier_set(bs);
1719
1720 // Create the hot card cache.
1721 _hot_card_cache = new G1HotCardCache(this);
1722
1723 // Also create a G1 rem set.
1724 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1725
1726 // Carve out the G1 part of the heap.
1727 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1728 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1729 G1RegionToSpaceMapper* heap_storage =
1730 G1RegionToSpaceMapper::create_mapper(g1_rs,
1731 g1_rs.size(),
1732 page_size,
1733 HeapRegion::GrainBytes,
1734 1,
1735 mtJavaHeap);
1736 os::trace_page_sizes("Heap",
1737 collector_policy()->min_heap_byte_size(),
1738 max_byte_size,
1739 page_size,
1740 heap_rs.base(),
1741 heap_rs.size());
1742 heap_storage->set_mapping_changed_listener(&_listener);
1743
1744 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1745 G1RegionToSpaceMapper* bot_storage =
1746 create_aux_memory_mapper("Block Offset Table",
1747 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1748 G1BlockOffsetTable::heap_map_factor());
1749
1750 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1751 G1RegionToSpaceMapper* cardtable_storage =
1752 create_aux_memory_mapper("Card Table",
1753 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1754 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1755
1756 G1RegionToSpaceMapper* card_counts_storage =
1757 create_aux_memory_mapper("Card Counts Table",
1758 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1759 G1CardCounts::heap_map_factor());
1760
1761 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1762 G1RegionToSpaceMapper* prev_bitmap_storage =
1763 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1764 G1RegionToSpaceMapper* next_bitmap_storage =
1765 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1766
1767 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1768 g1_barrier_set()->initialize(cardtable_storage);
1769 // Do later initialization work for concurrent refinement.
1770 _hot_card_cache->initialize(card_counts_storage);
1771
1772 // 6843694 - ensure that the maximum region index can fit
1773 // in the remembered set structures.
1774 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1775 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1776
1777 g1_rem_set()->initialize(max_capacity(), max_regions());
1778
1779 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1780 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1781 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1782 "too many cards per region");
1783
1784 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1785
1786 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1787
1788 {
1789 HeapWord* start = _hrm.reserved().start();
1790 HeapWord* end = _hrm.reserved().end();
1791 size_t granularity = HeapRegion::GrainBytes;
1792
1793 _in_cset_fast_test.initialize(start, end, granularity);
1794 _humongous_reclaim_candidates.initialize(start, end, granularity);
1795 }
1796
1797 // Create the G1ConcurrentMark data structure and thread.
1798 // (Must do this late, so that "max_regions" is defined.)
1799 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1800 if (_cm == NULL || !_cm->completed_initialization()) {
1801 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1802 return JNI_ENOMEM;
1803 }
1804 _cmThread = _cm->cmThread();
1805
1806 // Now expand into the initial heap size.
1807 if (!expand(init_byte_size, _workers)) {
1808 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1809 return JNI_ENOMEM;
1810 }
1811
1812 // Perform any initialization actions delegated to the policy.
1813 g1_policy()->init(this, &_collection_set);
1814
1815 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1816 SATB_Q_FL_lock,
1817 G1SATBProcessCompletedThreshold,
1818 Shared_SATB_Q_lock);
1819
1820 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1821 DirtyCardQ_CBL_mon,
1822 DirtyCardQ_FL_lock,
1823 (int)concurrent_g1_refine()->yellow_zone(),
1824 (int)concurrent_g1_refine()->red_zone(),
1825 Shared_DirtyCardQ_lock,
1826 NULL, // fl_owner
1827 true); // init_free_ids
1828
1829 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1830 DirtyCardQ_CBL_mon,
1831 DirtyCardQ_FL_lock,
1832 -1, // never trigger processing
1833 -1, // no limit on length
1834 Shared_DirtyCardQ_lock,
1835 &JavaThread::dirty_card_queue_set());
1836
1837 // Here we allocate the dummy HeapRegion that is required by the
1838 // G1AllocRegion class.
1839 HeapRegion* dummy_region = _hrm.get_dummy_region();
1840
1841 // We'll re-use the same region whether the alloc region will
1842 // require BOT updates or not and, if it doesn't, then a non-young
1843 // region will complain that it cannot support allocations without
1844 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1845 dummy_region->set_eden();
1846 // Make sure it's full.
1847 dummy_region->set_top(dummy_region->end());
1848 G1AllocRegion::setup(this, dummy_region);
1849
1850 _allocator->init_mutator_alloc_region();
1851
1852 // Do create of the monitoring and management support so that
1853 // values in the heap have been properly initialized.
1854 _g1mm = new G1MonitoringSupport(this);
1855
1856 G1StringDedup::initialize();
1857
1858 _preserved_marks_set.init(ParallelGCThreads);
1859
1860 _collection_set.initialize(max_regions());
1861
1862 return JNI_OK;
1863 }
1864
1865 void G1CollectedHeap::stop() {
1866 // Stop all concurrent threads. We do this to make sure these threads
1867 // do not continue to execute and access resources (e.g. logging)
1868 // that are destroyed during shutdown.
1869 _cg1r->stop();
1870 _cmThread->stop();
1871 if (G1StringDedup::is_enabled()) {
1872 G1StringDedup::stop();
1873 }
1874 }
1875
1876 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1877 return HeapRegion::max_region_size();
1878 }
1879
1880 void G1CollectedHeap::post_initialize() {
1881 ref_processing_init();
1882 }
1883
1884 void G1CollectedHeap::ref_processing_init() {
1885 // Reference processing in G1 currently works as follows:
1886 //
1887 // * There are two reference processor instances. One is
1888 // used to record and process discovered references
1889 // during concurrent marking; the other is used to
1890 // record and process references during STW pauses
1891 // (both full and incremental).
1892 // * Both ref processors need to 'span' the entire heap as
1893 // the regions in the collection set may be dotted around.
1894 //
1895 // * For the concurrent marking ref processor:
1896 // * Reference discovery is enabled at initial marking.
1897 // * Reference discovery is disabled and the discovered
1898 // references processed etc during remarking.
1899 // * Reference discovery is MT (see below).
1900 // * Reference discovery requires a barrier (see below).
1901 // * Reference processing may or may not be MT
1902 // (depending on the value of ParallelRefProcEnabled
1903 // and ParallelGCThreads).
1904 // * A full GC disables reference discovery by the CM
1905 // ref processor and abandons any entries on it's
1906 // discovered lists.
1907 //
1908 // * For the STW processor:
1909 // * Non MT discovery is enabled at the start of a full GC.
1910 // * Processing and enqueueing during a full GC is non-MT.
1911 // * During a full GC, references are processed after marking.
1912 //
1913 // * Discovery (may or may not be MT) is enabled at the start
1914 // of an incremental evacuation pause.
1915 // * References are processed near the end of a STW evacuation pause.
1916 // * For both types of GC:
1917 // * Discovery is atomic - i.e. not concurrent.
1918 // * Reference discovery will not need a barrier.
1919
1920 MemRegion mr = reserved_region();
1921
1922 // Concurrent Mark ref processor
1923 _ref_processor_cm =
1924 new ReferenceProcessor(mr, // span
1925 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1926 // mt processing
1927 ParallelGCThreads,
1928 // degree of mt processing
1929 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1930 // mt discovery
1931 MAX2(ParallelGCThreads, ConcGCThreads),
1932 // degree of mt discovery
1933 false,
1934 // Reference discovery is not atomic
1935 &_is_alive_closure_cm);
1936 // is alive closure
1937 // (for efficiency/performance)
1938
1939 // STW ref processor
1940 _ref_processor_stw =
1941 new ReferenceProcessor(mr, // span
1942 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1943 // mt processing
1944 ParallelGCThreads,
1945 // degree of mt processing
1946 (ParallelGCThreads > 1),
1947 // mt discovery
1948 ParallelGCThreads,
1949 // degree of mt discovery
1950 true,
1951 // Reference discovery is atomic
1952 &_is_alive_closure_stw);
1953 // is alive closure
1954 // (for efficiency/performance)
1955 }
1956
1957 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1958 return _collector_policy;
1959 }
1960
1961 size_t G1CollectedHeap::capacity() const {
1962 return _hrm.length() * HeapRegion::GrainBytes;
1963 }
1964
1965 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1966 hr->reset_gc_time_stamp();
1967 }
1968
1969 #ifndef PRODUCT
1970
1971 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1972 private:
1973 unsigned _gc_time_stamp;
1974 bool _failures;
1975
1976 public:
1977 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1978 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1979
1980 virtual bool doHeapRegion(HeapRegion* hr) {
1981 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1982 if (_gc_time_stamp != region_gc_time_stamp) {
1983 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1984 region_gc_time_stamp, _gc_time_stamp);
1985 _failures = true;
1986 }
1987 return false;
1988 }
1989
1990 bool failures() { return _failures; }
1991 };
1992
1993 void G1CollectedHeap::check_gc_time_stamps() {
1994 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1995 heap_region_iterate(&cl);
1996 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1997 }
1998 #endif // PRODUCT
1999
2000 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2001 _hot_card_cache->drain(cl, worker_i);
2002 }
2003
2004 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2005 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2006 size_t n_completed_buffers = 0;
2007 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2008 n_completed_buffers++;
2009 }
2010 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2011 dcqs.clear_n_completed_buffers();
2012 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2013 }
2014
2015 // Computes the sum of the storage used by the various regions.
2016 size_t G1CollectedHeap::used() const {
2017 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2018 if (_archive_allocator != NULL) {
2019 result += _archive_allocator->used();
2020 }
2021 return result;
2022 }
2023
2024 size_t G1CollectedHeap::used_unlocked() const {
2025 return _summary_bytes_used;
2026 }
2027
2028 class SumUsedClosure: public HeapRegionClosure {
2029 size_t _used;
2030 public:
2031 SumUsedClosure() : _used(0) {}
2032 bool doHeapRegion(HeapRegion* r) {
2033 _used += r->used();
2034 return false;
2035 }
2036 size_t result() { return _used; }
2037 };
2038
2039 size_t G1CollectedHeap::recalculate_used() const {
2040 double recalculate_used_start = os::elapsedTime();
2041
2042 SumUsedClosure blk;
2043 heap_region_iterate(&blk);
2044
2045 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2046 return blk.result();
2047 }
2048
2049 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2050 switch (cause) {
2051 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2052 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2053 case GCCause::_update_allocation_context_stats_inc: return true;
2054 case GCCause::_wb_conc_mark: return true;
2055 default : return false;
2056 }
2057 }
2058
2059 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2060 switch (cause) {
2061 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2062 case GCCause::_g1_humongous_allocation: return true;
2063 default: return is_user_requested_concurrent_full_gc(cause);
2064 }
2065 }
2066
2067 #ifndef PRODUCT
2068 void G1CollectedHeap::allocate_dummy_regions() {
2069 // Let's fill up most of the region
2070 size_t word_size = HeapRegion::GrainWords - 1024;
2071 // And as a result the region we'll allocate will be humongous.
2072 guarantee(is_humongous(word_size), "sanity");
2073
2074 // _filler_array_max_size is set to humongous object threshold
2075 // but temporarily change it to use CollectedHeap::fill_with_object().
2076 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2077
2078 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2079 // Let's use the existing mechanism for the allocation
2080 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2081 AllocationContext::system());
2082 if (dummy_obj != NULL) {
2083 MemRegion mr(dummy_obj, word_size);
2084 CollectedHeap::fill_with_object(mr);
2085 } else {
2086 // If we can't allocate once, we probably cannot allocate
2087 // again. Let's get out of the loop.
2088 break;
2089 }
2090 }
2091 }
2092 #endif // !PRODUCT
2093
2094 void G1CollectedHeap::increment_old_marking_cycles_started() {
2095 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2096 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2097 "Wrong marking cycle count (started: %d, completed: %d)",
2098 _old_marking_cycles_started, _old_marking_cycles_completed);
2099
2100 _old_marking_cycles_started++;
2101 }
2102
2103 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2104 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2105
2106 // We assume that if concurrent == true, then the caller is a
2107 // concurrent thread that was joined the Suspendible Thread
2108 // Set. If there's ever a cheap way to check this, we should add an
2109 // assert here.
2110
2111 // Given that this method is called at the end of a Full GC or of a
2112 // concurrent cycle, and those can be nested (i.e., a Full GC can
2113 // interrupt a concurrent cycle), the number of full collections
2114 // completed should be either one (in the case where there was no
2115 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2116 // behind the number of full collections started.
2117
2118 // This is the case for the inner caller, i.e. a Full GC.
2119 assert(concurrent ||
2120 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2121 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2122 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2123 "is inconsistent with _old_marking_cycles_completed = %u",
2124 _old_marking_cycles_started, _old_marking_cycles_completed);
2125
2126 // This is the case for the outer caller, i.e. the concurrent cycle.
2127 assert(!concurrent ||
2128 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2129 "for outer caller (concurrent cycle): "
2130 "_old_marking_cycles_started = %u "
2131 "is inconsistent with _old_marking_cycles_completed = %u",
2132 _old_marking_cycles_started, _old_marking_cycles_completed);
2133
2134 _old_marking_cycles_completed += 1;
2135
2136 // We need to clear the "in_progress" flag in the CM thread before
2137 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2138 // is set) so that if a waiter requests another System.gc() it doesn't
2139 // incorrectly see that a marking cycle is still in progress.
2140 if (concurrent) {
2141 _cmThread->set_idle();
2142 }
2143
2144 // This notify_all() will ensure that a thread that called
2145 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2146 // and it's waiting for a full GC to finish will be woken up. It is
2147 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2148 FullGCCount_lock->notify_all();
2149 }
2150
2151 void G1CollectedHeap::collect(GCCause::Cause cause) {
2152 assert_heap_not_locked();
2153
2154 uint gc_count_before;
2155 uint old_marking_count_before;
2156 uint full_gc_count_before;
2157 bool retry_gc;
2158
2159 do {
2160 retry_gc = false;
2161
2162 {
2163 MutexLocker ml(Heap_lock);
2164
2165 // Read the GC count while holding the Heap_lock
2166 gc_count_before = total_collections();
2167 full_gc_count_before = total_full_collections();
2168 old_marking_count_before = _old_marking_cycles_started;
2169 }
2170
2171 if (should_do_concurrent_full_gc(cause)) {
2172 // Schedule an initial-mark evacuation pause that will start a
2173 // concurrent cycle. We're setting word_size to 0 which means that
2174 // we are not requesting a post-GC allocation.
2175 VM_G1IncCollectionPause op(gc_count_before,
2176 0, /* word_size */
2177 true, /* should_initiate_conc_mark */
2178 g1_policy()->max_pause_time_ms(),
2179 cause);
2180 op.set_allocation_context(AllocationContext::current());
2181
2182 VMThread::execute(&op);
2183 if (!op.pause_succeeded()) {
2184 if (old_marking_count_before == _old_marking_cycles_started) {
2185 retry_gc = op.should_retry_gc();
2186 } else {
2187 // A Full GC happened while we were trying to schedule the
2188 // initial-mark GC. No point in starting a new cycle given
2189 // that the whole heap was collected anyway.
2190 }
2191
2192 if (retry_gc) {
2193 if (GCLocker::is_active_and_needs_gc()) {
2194 GCLocker::stall_until_clear();
2195 }
2196 }
2197 }
2198 } else {
2199 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2200 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2201
2202 // Schedule a standard evacuation pause. We're setting word_size
2203 // to 0 which means that we are not requesting a post-GC allocation.
2204 VM_G1IncCollectionPause op(gc_count_before,
2205 0, /* word_size */
2206 false, /* should_initiate_conc_mark */
2207 g1_policy()->max_pause_time_ms(),
2208 cause);
2209 VMThread::execute(&op);
2210 } else {
2211 // Schedule a Full GC.
2212 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2213 VMThread::execute(&op);
2214 }
2215 }
2216 } while (retry_gc);
2217 }
2218
2219 bool G1CollectedHeap::is_in(const void* p) const {
2220 if (_hrm.reserved().contains(p)) {
2221 // Given that we know that p is in the reserved space,
2222 // heap_region_containing() should successfully
2223 // return the containing region.
2224 HeapRegion* hr = heap_region_containing(p);
2225 return hr->is_in(p);
2226 } else {
2227 return false;
2228 }
2229 }
2230
2231 #ifdef ASSERT
2232 bool G1CollectedHeap::is_in_exact(const void* p) const {
2233 bool contains = reserved_region().contains(p);
2234 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2235 if (contains && available) {
2236 return true;
2237 } else {
2238 return false;
2239 }
2240 }
2241 #endif
2242
2243 // Iteration functions.
2244
2245 // Iterates an ObjectClosure over all objects within a HeapRegion.
2246
2247 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2248 ObjectClosure* _cl;
2249 public:
2250 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2251 bool doHeapRegion(HeapRegion* r) {
2252 if (!r->is_continues_humongous()) {
2253 r->object_iterate(_cl);
2254 }
2255 return false;
2256 }
2257 };
2258
2259 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2260 IterateObjectClosureRegionClosure blk(cl);
2261 heap_region_iterate(&blk);
2262 }
2263
2264 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2265 _hrm.iterate(cl);
2266 }
2267
2268 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2269 uint worker_id,
2270 HeapRegionClaimerBase *hrclaimer) const {
2271 _hrm.par_iterate(cl, worker_id, hrclaimer);
2272 }
2273
2274 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2275 _collection_set.iterate(cl);
2276 }
2277
2278 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2279 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2280 }
2281
2282 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2283 HeapRegion* hr = heap_region_containing(addr);
2284 return hr->block_start(addr);
2285 }
2286
2287 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2288 HeapRegion* hr = heap_region_containing(addr);
2289 return hr->block_size(addr);
2290 }
2291
2292 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2293 HeapRegion* hr = heap_region_containing(addr);
2294 return hr->block_is_obj(addr);
2295 }
2296
2297 bool G1CollectedHeap::supports_tlab_allocation() const {
2298 return true;
2299 }
2300
2301 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2302 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2303 }
2304
2305 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2306 return _eden.length() * HeapRegion::GrainBytes;
2307 }
2308
2309 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2310 // must be equal to the humongous object limit.
2311 size_t G1CollectedHeap::max_tlab_size() const {
2312 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2313 }
2314
2315 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2316 AllocationContext_t context = AllocationContext::current();
2317 return _allocator->unsafe_max_tlab_alloc(context);
2318 }
2319
2320 size_t G1CollectedHeap::max_capacity() const {
2321 return _hrm.reserved().byte_size();
2322 }
2323
2324 jlong G1CollectedHeap::millis_since_last_gc() {
2325 // See the notes in GenCollectedHeap::millis_since_last_gc()
2326 // for more information about the implementation.
2327 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2328 _g1_policy->collection_pause_end_millis();
2329 if (ret_val < 0) {
2330 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2331 ". returning zero instead.", ret_val);
2332 return 0;
2333 }
2334 return ret_val;
2335 }
2336
2337 void G1CollectedHeap::prepare_for_verify() {
2338 _verifier->prepare_for_verify();
2339 }
2340
2341 void G1CollectedHeap::verify(VerifyOption vo) {
2342 _verifier->verify(vo);
2343 }
2344
2345 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2346 return true;
2347 }
2348
2349 const char* const* G1CollectedHeap::concurrent_phases() const {
2350 return _cmThread->concurrent_phases();
2351 }
2352
2353 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2354 return _cmThread->request_concurrent_phase(phase);
2355 }
2356
2357 class PrintRegionClosure: public HeapRegionClosure {
2358 outputStream* _st;
2359 public:
2360 PrintRegionClosure(outputStream* st) : _st(st) {}
2361 bool doHeapRegion(HeapRegion* r) {
2362 r->print_on(_st);
2363 return false;
2364 }
2365 };
2366
2367 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2368 const HeapRegion* hr,
2369 const VerifyOption vo) const {
2370 switch (vo) {
2371 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2372 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2373 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2374 default: ShouldNotReachHere();
2375 }
2376 return false; // keep some compilers happy
2377 }
2378
2379 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2380 const VerifyOption vo) const {
2381 switch (vo) {
2382 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2383 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2384 case VerifyOption_G1UseMarkWord: {
2385 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2386 return !obj->is_gc_marked() && !hr->is_archive();
2387 }
2388 default: ShouldNotReachHere();
2389 }
2390 return false; // keep some compilers happy
2391 }
2392
2393 void G1CollectedHeap::print_heap_regions() const {
2394 Log(gc, heap, region) log;
2395 if (log.is_trace()) {
2396 ResourceMark rm;
2397 print_regions_on(log.trace_stream());
2398 }
2399 }
2400
2401 void G1CollectedHeap::print_on(outputStream* st) const {
2402 st->print(" %-20s", "garbage-first heap");
2403 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2404 capacity()/K, used_unlocked()/K);
2405 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2406 p2i(_hrm.reserved().start()),
2407 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2408 p2i(_hrm.reserved().end()));
2409 st->cr();
2410 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2411 uint young_regions = young_regions_count();
2412 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2413 (size_t) young_regions * HeapRegion::GrainBytes / K);
2414 uint survivor_regions = survivor_regions_count();
2415 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2416 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2417 st->cr();
2418 MetaspaceAux::print_on(st);
2419 }
2420
2421 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2422 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2423 "HS=humongous(starts), HC=humongous(continues), "
2424 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2425 "AC=allocation context, "
2426 "TAMS=top-at-mark-start (previous, next)");
2427 PrintRegionClosure blk(st);
2428 heap_region_iterate(&blk);
2429 }
2430
2431 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2432 print_on(st);
2433
2434 // Print the per-region information.
2435 print_regions_on(st);
2436 }
2437
2438 void G1CollectedHeap::print_on_error(outputStream* st) const {
2439 this->CollectedHeap::print_on_error(st);
2440
2441 if (_cm != NULL) {
2442 st->cr();
2443 _cm->print_on_error(st);
2444 }
2445 }
2446
2447 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2448 workers()->print_worker_threads_on(st);
2449 _cmThread->print_on(st);
2450 st->cr();
2451 _cm->print_worker_threads_on(st);
2452 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2453 if (G1StringDedup::is_enabled()) {
2454 G1StringDedup::print_worker_threads_on(st);
2455 }
2456 }
2457
2458 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2459 workers()->threads_do(tc);
2460 tc->do_thread(_cmThread);
2461 _cm->threads_do(tc);
2462 _cg1r->threads_do(tc); // also iterates over the sample thread
2463 if (G1StringDedup::is_enabled()) {
2464 G1StringDedup::threads_do(tc);
2465 }
2466 }
2467
2468 void G1CollectedHeap::print_tracing_info() const {
2469 g1_rem_set()->print_summary_info();
2470 concurrent_mark()->print_summary_info();
2471 }
2472
2473 #ifndef PRODUCT
2474 // Helpful for debugging RSet issues.
2475
2476 class PrintRSetsClosure : public HeapRegionClosure {
2477 private:
2478 const char* _msg;
2479 size_t _occupied_sum;
2480
2481 public:
2482 bool doHeapRegion(HeapRegion* r) {
2483 HeapRegionRemSet* hrrs = r->rem_set();
2484 size_t occupied = hrrs->occupied();
2485 _occupied_sum += occupied;
2486
2487 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2488 if (occupied == 0) {
2489 tty->print_cr(" RSet is empty");
2490 } else {
2491 hrrs->print();
2492 }
2493 tty->print_cr("----------");
2494 return false;
2495 }
2496
2497 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2498 tty->cr();
2499 tty->print_cr("========================================");
2500 tty->print_cr("%s", msg);
2501 tty->cr();
2502 }
2503
2504 ~PrintRSetsClosure() {
2505 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2506 tty->print_cr("========================================");
2507 tty->cr();
2508 }
2509 };
2510
2511 void G1CollectedHeap::print_cset_rsets() {
2512 PrintRSetsClosure cl("Printing CSet RSets");
2513 collection_set_iterate(&cl);
2514 }
2515
2516 void G1CollectedHeap::print_all_rsets() {
2517 PrintRSetsClosure cl("Printing All RSets");;
2518 heap_region_iterate(&cl);
2519 }
2520 #endif // PRODUCT
2521
2522 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2523
2524 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2525 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2526 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2527
2528 size_t eden_capacity_bytes =
2529 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2530
2531 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2532 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2533 eden_capacity_bytes, survivor_used_bytes, num_regions());
2534 }
2535
2536 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2537 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2538 stats->unused(), stats->used(), stats->region_end_waste(),
2539 stats->regions_filled(), stats->direct_allocated(),
2540 stats->failure_used(), stats->failure_waste());
2541 }
2542
2543 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2544 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2545 gc_tracer->report_gc_heap_summary(when, heap_summary);
2546
2547 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2548 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2549 }
2550
2551 G1CollectedHeap* G1CollectedHeap::heap() {
2552 CollectedHeap* heap = Universe::heap();
2553 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2554 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2555 return (G1CollectedHeap*)heap;
2556 }
2557
2558 void G1CollectedHeap::gc_prologue(bool full) {
2559 // always_do_update_barrier = false;
2560 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2561
2562 // This summary needs to be printed before incrementing total collections.
2563 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2564
2565 // Update common counters.
2566 increment_total_collections(full /* full gc */);
2567 if (full) {
2568 increment_old_marking_cycles_started();
2569 reset_gc_time_stamp();
2570 } else {
2571 increment_gc_time_stamp();
2572 }
2573
2574 // Fill TLAB's and such
2575 double start = os::elapsedTime();
2576 accumulate_statistics_all_tlabs();
2577 ensure_parsability(true);
2578 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2579 }
2580
2581 void G1CollectedHeap::gc_epilogue(bool full) {
2582 // Update common counters.
2583 if (full) {
2584 // Update the number of full collections that have been completed.
2585 increment_old_marking_cycles_completed(false /* concurrent */);
2586 }
2587
2588 // We are at the end of the GC. Total collections has already been increased.
2589 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2590
2591 // FIXME: what is this about?
2592 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2593 // is set.
2594 #if defined(COMPILER2) || INCLUDE_JVMCI
2595 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2596 #endif
2597 // always_do_update_barrier = true;
2598
2599 double start = os::elapsedTime();
2600 resize_all_tlabs();
2601 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2602
2603 allocation_context_stats().update(full);
2604
2605 MemoryService::track_memory_usage();
2606 // We have just completed a GC. Update the soft reference
2607 // policy with the new heap occupancy
2608 Universe::update_heap_info_at_gc();
2609 }
2610
2611 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2612 uint gc_count_before,
2613 bool* succeeded,
2614 GCCause::Cause gc_cause) {
2615 assert_heap_not_locked_and_not_at_safepoint();
2616 VM_G1IncCollectionPause op(gc_count_before,
2617 word_size,
2618 false, /* should_initiate_conc_mark */
2619 g1_policy()->max_pause_time_ms(),
2620 gc_cause);
2621
2622 op.set_allocation_context(AllocationContext::current());
2623 VMThread::execute(&op);
2624
2625 HeapWord* result = op.result();
2626 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2627 assert(result == NULL || ret_succeeded,
2628 "the result should be NULL if the VM did not succeed");
2629 *succeeded = ret_succeeded;
2630
2631 assert_heap_not_locked();
2632 return result;
2633 }
2634
2635 void
2636 G1CollectedHeap::doConcurrentMark() {
2637 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2638 if (!_cmThread->in_progress()) {
2639 _cmThread->set_started();
2640 CGC_lock->notify();
2641 }
2642 }
2643
2644 size_t G1CollectedHeap::pending_card_num() {
2645 size_t extra_cards = 0;
2646 JavaThread *curr = Threads::first();
2647 while (curr != NULL) {
2648 DirtyCardQueue& dcq = curr->dirty_card_queue();
2649 extra_cards += dcq.size();
2650 curr = curr->next();
2651 }
2652 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2653 size_t buffer_size = dcqs.buffer_size();
2654 size_t buffer_num = dcqs.completed_buffers_num();
2655
2656 return buffer_size * buffer_num + extra_cards;
2657 }
2658
2659 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2660 private:
2661 size_t _total_humongous;
2662 size_t _candidate_humongous;
2663
2664 DirtyCardQueue _dcq;
2665
2666 // We don't nominate objects with many remembered set entries, on
2667 // the assumption that such objects are likely still live.
2668 bool is_remset_small(HeapRegion* region) const {
2669 HeapRegionRemSet* const rset = region->rem_set();
2670 return G1EagerReclaimHumongousObjectsWithStaleRefs
2671 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2672 : rset->is_empty();
2673 }
2674
2675 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2676 assert(region->is_starts_humongous(), "Must start a humongous object");
2677
2678 oop obj = oop(region->bottom());
2679
2680 // Dead objects cannot be eager reclaim candidates. Due to class
2681 // unloading it is unsafe to query their classes so we return early.
2682 if (heap->is_obj_dead(obj, region)) {
2683 return false;
2684 }
2685
2686 // Candidate selection must satisfy the following constraints
2687 // while concurrent marking is in progress:
2688 //
2689 // * In order to maintain SATB invariants, an object must not be
2690 // reclaimed if it was allocated before the start of marking and
2691 // has not had its references scanned. Such an object must have
2692 // its references (including type metadata) scanned to ensure no
2693 // live objects are missed by the marking process. Objects
2694 // allocated after the start of concurrent marking don't need to
2695 // be scanned.
2696 //
2697 // * An object must not be reclaimed if it is on the concurrent
2698 // mark stack. Objects allocated after the start of concurrent
2699 // marking are never pushed on the mark stack.
2700 //
2701 // Nominating only objects allocated after the start of concurrent
2702 // marking is sufficient to meet both constraints. This may miss
2703 // some objects that satisfy the constraints, but the marking data
2704 // structures don't support efficiently performing the needed
2705 // additional tests or scrubbing of the mark stack.
2706 //
2707 // However, we presently only nominate is_typeArray() objects.
2708 // A humongous object containing references induces remembered
2709 // set entries on other regions. In order to reclaim such an
2710 // object, those remembered sets would need to be cleaned up.
2711 //
2712 // We also treat is_typeArray() objects specially, allowing them
2713 // to be reclaimed even if allocated before the start of
2714 // concurrent mark. For this we rely on mark stack insertion to
2715 // exclude is_typeArray() objects, preventing reclaiming an object
2716 // that is in the mark stack. We also rely on the metadata for
2717 // such objects to be built-in and so ensured to be kept live.
2718 // Frequent allocation and drop of large binary blobs is an
2719 // important use case for eager reclaim, and this special handling
2720 // may reduce needed headroom.
2721
2722 return obj->is_typeArray() && is_remset_small(region);
2723 }
2724
2725 public:
2726 RegisterHumongousWithInCSetFastTestClosure()
2727 : _total_humongous(0),
2728 _candidate_humongous(0),
2729 _dcq(&JavaThread::dirty_card_queue_set()) {
2730 }
2731
2732 virtual bool doHeapRegion(HeapRegion* r) {
2733 if (!r->is_starts_humongous()) {
2734 return false;
2735 }
2736 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2737
2738 bool is_candidate = humongous_region_is_candidate(g1h, r);
2739 uint rindex = r->hrm_index();
2740 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2741 if (is_candidate) {
2742 _candidate_humongous++;
2743 g1h->register_humongous_region_with_cset(rindex);
2744 // Is_candidate already filters out humongous object with large remembered sets.
2745 // If we have a humongous object with a few remembered sets, we simply flush these
2746 // remembered set entries into the DCQS. That will result in automatic
2747 // re-evaluation of their remembered set entries during the following evacuation
2748 // phase.
2749 if (!r->rem_set()->is_empty()) {
2750 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2751 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2752 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2753 HeapRegionRemSetIterator hrrs(r->rem_set());
2754 size_t card_index;
2755 while (hrrs.has_next(card_index)) {
2756 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2757 // The remembered set might contain references to already freed
2758 // regions. Filter out such entries to avoid failing card table
2759 // verification.
2760 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2761 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2762 *card_ptr = CardTableModRefBS::dirty_card_val();
2763 _dcq.enqueue(card_ptr);
2764 }
2765 }
2766 }
2767 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2768 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2769 hrrs.n_yielded(), r->rem_set()->occupied());
2770 r->rem_set()->clear_locked();
2771 }
2772 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2773 }
2774 _total_humongous++;
2775
2776 return false;
2777 }
2778
2779 size_t total_humongous() const { return _total_humongous; }
2780 size_t candidate_humongous() const { return _candidate_humongous; }
2781
2782 void flush_rem_set_entries() { _dcq.flush(); }
2783 };
2784
2785 void G1CollectedHeap::register_humongous_regions_with_cset() {
2786 if (!G1EagerReclaimHumongousObjects) {
2787 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2788 return;
2789 }
2790 double time = os::elapsed_counter();
2791
2792 // Collect reclaim candidate information and register candidates with cset.
2793 RegisterHumongousWithInCSetFastTestClosure cl;
2794 heap_region_iterate(&cl);
2795
2796 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2797 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2798 cl.total_humongous(),
2799 cl.candidate_humongous());
2800 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2801
2802 // Finally flush all remembered set entries to re-check into the global DCQS.
2803 cl.flush_rem_set_entries();
2804 }
2805
2806 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2807 public:
2808 bool doHeapRegion(HeapRegion* hr) {
2809 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2810 hr->verify_rem_set();
2811 }
2812 return false;
2813 }
2814 };
2815
2816 uint G1CollectedHeap::num_task_queues() const {
2817 return _task_queues->size();
2818 }
2819
2820 #if TASKQUEUE_STATS
2821 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2822 st->print_raw_cr("GC Task Stats");
2823 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2824 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2825 }
2826
2827 void G1CollectedHeap::print_taskqueue_stats() const {
2828 if (!log_is_enabled(Trace, gc, task, stats)) {
2829 return;
2830 }
2831 Log(gc, task, stats) log;
2832 ResourceMark rm;
2833 outputStream* st = log.trace_stream();
2834
2835 print_taskqueue_stats_hdr(st);
2836
2837 TaskQueueStats totals;
2838 const uint n = num_task_queues();
2839 for (uint i = 0; i < n; ++i) {
2840 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2841 totals += task_queue(i)->stats;
2842 }
2843 st->print_raw("tot "); totals.print(st); st->cr();
2844
2845 DEBUG_ONLY(totals.verify());
2846 }
2847
2848 void G1CollectedHeap::reset_taskqueue_stats() {
2849 const uint n = num_task_queues();
2850 for (uint i = 0; i < n; ++i) {
2851 task_queue(i)->stats.reset();
2852 }
2853 }
2854 #endif // TASKQUEUE_STATS
2855
2856 void G1CollectedHeap::wait_for_root_region_scanning() {
2857 double scan_wait_start = os::elapsedTime();
2858 // We have to wait until the CM threads finish scanning the
2859 // root regions as it's the only way to ensure that all the
2860 // objects on them have been correctly scanned before we start
2861 // moving them during the GC.
2862 bool waited = _cm->root_regions()->wait_until_scan_finished();
2863 double wait_time_ms = 0.0;
2864 if (waited) {
2865 double scan_wait_end = os::elapsedTime();
2866 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2867 }
2868 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2869 }
2870
2871 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2872 private:
2873 G1HRPrinter* _hr_printer;
2874 public:
2875 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2876
2877 virtual bool doHeapRegion(HeapRegion* r) {
2878 _hr_printer->cset(r);
2879 return false;
2880 }
2881 };
2882
2883 void G1CollectedHeap::start_new_collection_set() {
2884 collection_set()->start_incremental_building();
2885
2886 clear_cset_fast_test();
2887
2888 guarantee(_eden.length() == 0, "eden should have been cleared");
2889 g1_policy()->transfer_survivors_to_cset(survivor());
2890 }
2891
2892 bool
2893 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2894 assert_at_safepoint(true /* should_be_vm_thread */);
2895 guarantee(!is_gc_active(), "collection is not reentrant");
2896
2897 if (GCLocker::check_active_before_gc()) {
2898 return false;
2899 }
2900
2901 _gc_timer_stw->register_gc_start();
2902
2903 GCIdMark gc_id_mark;
2904 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2905
2906 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2907 ResourceMark rm;
2908
2909 g1_policy()->note_gc_start();
2910
2911 wait_for_root_region_scanning();
2912
2913 print_heap_before_gc();
2914 print_heap_regions();
2915 trace_heap_before_gc(_gc_tracer_stw);
2916
2917 _verifier->verify_region_sets_optional();
2918 _verifier->verify_dirty_young_regions();
2919
2920 // We should not be doing initial mark unless the conc mark thread is running
2921 if (!_cmThread->should_terminate()) {
2922 // This call will decide whether this pause is an initial-mark
2923 // pause. If it is, during_initial_mark_pause() will return true
2924 // for the duration of this pause.
2925 g1_policy()->decide_on_conc_mark_initiation();
2926 }
2927
2928 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2929 assert(!collector_state()->during_initial_mark_pause() ||
2930 collector_state()->gcs_are_young(), "sanity");
2931
2932 // We also do not allow mixed GCs during marking.
2933 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2934
2935 // Record whether this pause is an initial mark. When the current
2936 // thread has completed its logging output and it's safe to signal
2937 // the CM thread, the flag's value in the policy has been reset.
2938 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2939
2940 // Inner scope for scope based logging, timers, and stats collection
2941 {
2942 EvacuationInfo evacuation_info;
2943
2944 if (collector_state()->during_initial_mark_pause()) {
2945 // We are about to start a marking cycle, so we increment the
2946 // full collection counter.
2947 increment_old_marking_cycles_started();
2948 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2949 }
2950
2951 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2952
2953 GCTraceCPUTime tcpu;
2954
2955 FormatBuffer<> gc_string("Pause ");
2956 if (collector_state()->during_initial_mark_pause()) {
2957 gc_string.append("Initial Mark");
2958 } else if (collector_state()->gcs_are_young()) {
2959 gc_string.append("Young");
2960 } else {
2961 gc_string.append("Mixed");
2962 }
2963 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2964
2965 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2966 workers()->active_workers(),
2967 Threads::number_of_non_daemon_threads());
2968 workers()->update_active_workers(active_workers);
2969 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2970
2971 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2972 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2973
2974 // If the secondary_free_list is not empty, append it to the
2975 // free_list. No need to wait for the cleanup operation to finish;
2976 // the region allocation code will check the secondary_free_list
2977 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2978 // set, skip this step so that the region allocation code has to
2979 // get entries from the secondary_free_list.
2980 if (!G1StressConcRegionFreeing) {
2981 append_secondary_free_list_if_not_empty_with_lock();
2982 }
2983
2984 G1HeapTransition heap_transition(this);
2985 size_t heap_used_bytes_before_gc = used();
2986
2987 // Don't dynamically change the number of GC threads this early. A value of
2988 // 0 is used to indicate serial work. When parallel work is done,
2989 // it will be set.
2990
2991 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2992 IsGCActiveMark x;
2993
2994 gc_prologue(false);
2995
2996 if (VerifyRememberedSets) {
2997 log_info(gc, verify)("[Verifying RemSets before GC]");
2998 VerifyRegionRemSetClosure v_cl;
2999 heap_region_iterate(&v_cl);
3000 }
3001
3002 _verifier->verify_before_gc();
3003
3004 _verifier->check_bitmaps("GC Start");
3005
3006 #if defined(COMPILER2) || INCLUDE_JVMCI
3007 DerivedPointerTable::clear();
3008 #endif
3009
3010 // Please see comment in g1CollectedHeap.hpp and
3011 // G1CollectedHeap::ref_processing_init() to see how
3012 // reference processing currently works in G1.
3013
3014 // Enable discovery in the STW reference processor
3015 if (g1_policy()->should_process_references()) {
3016 ref_processor_stw()->enable_discovery();
3017 } else {
3018 ref_processor_stw()->disable_discovery();
3019 }
3020
3021 {
3022 // We want to temporarily turn off discovery by the
3023 // CM ref processor, if necessary, and turn it back on
3024 // on again later if we do. Using a scoped
3025 // NoRefDiscovery object will do this.
3026 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3027
3028 // Forget the current alloc region (we might even choose it to be part
3029 // of the collection set!).
3030 _allocator->release_mutator_alloc_region();
3031
3032 // This timing is only used by the ergonomics to handle our pause target.
3033 // It is unclear why this should not include the full pause. We will
3034 // investigate this in CR 7178365.
3035 //
3036 // Preserving the old comment here if that helps the investigation:
3037 //
3038 // The elapsed time induced by the start time below deliberately elides
3039 // the possible verification above.
3040 double sample_start_time_sec = os::elapsedTime();
3041
3042 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3043
3044 if (collector_state()->during_initial_mark_pause()) {
3045 concurrent_mark()->checkpointRootsInitialPre();
3046 }
3047
3048 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3049
3050 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3051
3052 // Make sure the remembered sets are up to date. This needs to be
3053 // done before register_humongous_regions_with_cset(), because the
3054 // remembered sets are used there to choose eager reclaim candidates.
3055 // If the remembered sets are not up to date we might miss some
3056 // entries that need to be handled.
3057 g1_rem_set()->cleanupHRRS();
3058
3059 register_humongous_regions_with_cset();
3060
3061 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3062
3063 // We call this after finalize_cset() to
3064 // ensure that the CSet has been finalized.
3065 _cm->verify_no_cset_oops();
3066
3067 if (_hr_printer.is_active()) {
3068 G1PrintCollectionSetClosure cl(&_hr_printer);
3069 _collection_set.iterate(&cl);
3070 }
3071
3072 // Initialize the GC alloc regions.
3073 _allocator->init_gc_alloc_regions(evacuation_info);
3074
3075 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3076 pre_evacuate_collection_set();
3077
3078 // Actually do the work...
3079 evacuate_collection_set(evacuation_info, &per_thread_states);
3080
3081 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3082
3083 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3084 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3085
3086 eagerly_reclaim_humongous_regions();
3087
3088 record_obj_copy_mem_stats();
3089 _survivor_evac_stats.adjust_desired_plab_sz();
3090 _old_evac_stats.adjust_desired_plab_sz();
3091
3092 double start = os::elapsedTime();
3093 start_new_collection_set();
3094 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3095
3096 if (evacuation_failed()) {
3097 set_used(recalculate_used());
3098 if (_archive_allocator != NULL) {
3099 _archive_allocator->clear_used();
3100 }
3101 for (uint i = 0; i < ParallelGCThreads; i++) {
3102 if (_evacuation_failed_info_array[i].has_failed()) {
3103 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3104 }
3105 }
3106 } else {
3107 // The "used" of the the collection set have already been subtracted
3108 // when they were freed. Add in the bytes evacuated.
3109 increase_used(g1_policy()->bytes_copied_during_gc());
3110 }
3111
3112 if (collector_state()->during_initial_mark_pause()) {
3113 // We have to do this before we notify the CM threads that
3114 // they can start working to make sure that all the
3115 // appropriate initialization is done on the CM object.
3116 concurrent_mark()->checkpointRootsInitialPost();
3117 collector_state()->set_mark_in_progress(true);
3118 // Note that we don't actually trigger the CM thread at
3119 // this point. We do that later when we're sure that
3120 // the current thread has completed its logging output.
3121 }
3122
3123 allocate_dummy_regions();
3124
3125 _allocator->init_mutator_alloc_region();
3126
3127 {
3128 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3129 if (expand_bytes > 0) {
3130 size_t bytes_before = capacity();
3131 // No need for an ergo logging here,
3132 // expansion_amount() does this when it returns a value > 0.
3133 double expand_ms;
3134 if (!expand(expand_bytes, _workers, &expand_ms)) {
3135 // We failed to expand the heap. Cannot do anything about it.
3136 }
3137 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3138 }
3139 }
3140
3141 // We redo the verification but now wrt to the new CSet which
3142 // has just got initialized after the previous CSet was freed.
3143 _cm->verify_no_cset_oops();
3144
3145 // This timing is only used by the ergonomics to handle our pause target.
3146 // It is unclear why this should not include the full pause. We will
3147 // investigate this in CR 7178365.
3148 double sample_end_time_sec = os::elapsedTime();
3149 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3150 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3151 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3152
3153 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3154 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3155
3156 if (VerifyRememberedSets) {
3157 log_info(gc, verify)("[Verifying RemSets after GC]");
3158 VerifyRegionRemSetClosure v_cl;
3159 heap_region_iterate(&v_cl);
3160 }
3161
3162 _verifier->verify_after_gc();
3163 _verifier->check_bitmaps("GC End");
3164
3165 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3166 ref_processor_stw()->verify_no_references_recorded();
3167
3168 // CM reference discovery will be re-enabled if necessary.
3169 }
3170
3171 #ifdef TRACESPINNING
3172 ParallelTaskTerminator::print_termination_counts();
3173 #endif
3174
3175 gc_epilogue(false);
3176 }
3177
3178 // Print the remainder of the GC log output.
3179 if (evacuation_failed()) {
3180 log_info(gc)("To-space exhausted");
3181 }
3182
3183 g1_policy()->print_phases();
3184 heap_transition.print();
3185
3186 // It is not yet to safe to tell the concurrent mark to
3187 // start as we have some optional output below. We don't want the
3188 // output from the concurrent mark thread interfering with this
3189 // logging output either.
3190
3191 _hrm.verify_optional();
3192 _verifier->verify_region_sets_optional();
3193
3194 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3195 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3196
3197 print_heap_after_gc();
3198 print_heap_regions();
3199 trace_heap_after_gc(_gc_tracer_stw);
3200
3201 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3202 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3203 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3204 // before any GC notifications are raised.
3205 g1mm()->update_sizes();
3206
3207 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3208 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3209 _gc_timer_stw->register_gc_end();
3210 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3211 }
3212 // It should now be safe to tell the concurrent mark thread to start
3213 // without its logging output interfering with the logging output
3214 // that came from the pause.
3215
3216 if (should_start_conc_mark) {
3217 // CAUTION: after the doConcurrentMark() call below,
3218 // the concurrent marking thread(s) could be running
3219 // concurrently with us. Make sure that anything after
3220 // this point does not assume that we are the only GC thread
3221 // running. Note: of course, the actual marking work will
3222 // not start until the safepoint itself is released in
3223 // SuspendibleThreadSet::desynchronize().
3224 doConcurrentMark();
3225 }
3226
3227 return true;
3228 }
3229
3230 void G1CollectedHeap::remove_self_forwarding_pointers() {
3231 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3232 workers()->run_task(&rsfp_task);
3233 }
3234
3235 void G1CollectedHeap::restore_after_evac_failure() {
3236 double remove_self_forwards_start = os::elapsedTime();
3237
3238 remove_self_forwarding_pointers();
3239 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3240 _preserved_marks_set.restore(&task_executor);
3241
3242 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3243 }
3244
3245 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3246 if (!_evacuation_failed) {
3247 _evacuation_failed = true;
3248 }
3249
3250 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3251 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3252 }
3253
3254 bool G1ParEvacuateFollowersClosure::offer_termination() {
3255 G1ParScanThreadState* const pss = par_scan_state();
3256 start_term_time();
3257 const bool res = terminator()->offer_termination();
3258 end_term_time();
3259 return res;
3260 }
3261
3262 void G1ParEvacuateFollowersClosure::do_void() {
3263 G1ParScanThreadState* const pss = par_scan_state();
3264 pss->trim_queue();
3265 do {
3266 pss->steal_and_trim_queue(queues());
3267 } while (!offer_termination());
3268 }
3269
3270 class G1ParTask : public AbstractGangTask {
3271 protected:
3272 G1CollectedHeap* _g1h;
3273 G1ParScanThreadStateSet* _pss;
3274 RefToScanQueueSet* _queues;
3275 G1RootProcessor* _root_processor;
3276 ParallelTaskTerminator _terminator;
3277 uint _n_workers;
3278
3279 public:
3280 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3281 : AbstractGangTask("G1 collection"),
3282 _g1h(g1h),
3283 _pss(per_thread_states),
3284 _queues(task_queues),
3285 _root_processor(root_processor),
3286 _terminator(n_workers, _queues),
3287 _n_workers(n_workers)
3288 {}
3289
3290 void work(uint worker_id) {
3291 if (worker_id >= _n_workers) return; // no work needed this round
3292
3293 double start_sec = os::elapsedTime();
3294 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3295
3296 {
3297 ResourceMark rm;
3298 HandleMark hm;
3299
3300 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3301
3302 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3303 pss->set_ref_processor(rp);
3304
3305 double start_strong_roots_sec = os::elapsedTime();
3306
3307 _root_processor->evacuate_roots(pss->closures(), worker_id);
3308
3309 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3310 // treating the nmethods visited to act as roots for concurrent marking.
3311 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3312 // objects copied by the current evacuation.
3313 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3314 pss->closures()->weak_codeblobs(),
3315 worker_id);
3316
3317 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3318
3319 double term_sec = 0.0;
3320 size_t evac_term_attempts = 0;
3321 {
3322 double start = os::elapsedTime();
3323 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3324 evac.do_void();
3325
3326 evac_term_attempts = evac.term_attempts();
3327 term_sec = evac.term_time();
3328 double elapsed_sec = os::elapsedTime() - start;
3329 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3330 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3331 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3332 }
3333
3334 assert(pss->queue_is_empty(), "should be empty");
3335
3336 if (log_is_enabled(Debug, gc, task, stats)) {
3337 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3338 size_t lab_waste;
3339 size_t lab_undo_waste;
3340 pss->waste(lab_waste, lab_undo_waste);
3341 _g1h->print_termination_stats(worker_id,
3342 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3343 strong_roots_sec * 1000.0, /* strong roots time */
3344 term_sec * 1000.0, /* evac term time */
3345 evac_term_attempts, /* evac term attempts */
3346 lab_waste, /* alloc buffer waste */
3347 lab_undo_waste /* undo waste */
3348 );
3349 }
3350
3351 // Close the inner scope so that the ResourceMark and HandleMark
3352 // destructors are executed here and are included as part of the
3353 // "GC Worker Time".
3354 }
3355 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3356 }
3357 };
3358
3359 void G1CollectedHeap::print_termination_stats_hdr() {
3360 log_debug(gc, task, stats)("GC Termination Stats");
3361 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3362 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3363 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3364 }
3365
3366 void G1CollectedHeap::print_termination_stats(uint worker_id,
3367 double elapsed_ms,
3368 double strong_roots_ms,
3369 double term_ms,
3370 size_t term_attempts,
3371 size_t alloc_buffer_waste,
3372 size_t undo_waste) const {
3373 log_debug(gc, task, stats)
3374 ("%3d %9.2f %9.2f %6.2f "
3375 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3376 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3377 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3378 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3379 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3380 alloc_buffer_waste * HeapWordSize / K,
3381 undo_waste * HeapWordSize / K);
3382 }
3383
3384 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3385 private:
3386 BoolObjectClosure* _is_alive;
3387 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3388
3389 int _initial_string_table_size;
3390 int _initial_symbol_table_size;
3391
3392 bool _process_strings;
3393 int _strings_processed;
3394 int _strings_removed;
3395
3396 bool _process_symbols;
3397 int _symbols_processed;
3398 int _symbols_removed;
3399
3400 bool _process_string_dedup;
3401
3402 public:
3403 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3404 AbstractGangTask("String/Symbol Unlinking"),
3405 _is_alive(is_alive),
3406 _dedup_closure(is_alive, NULL, false),
3407 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3408 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3409 _process_string_dedup(process_string_dedup) {
3410
3411 _initial_string_table_size = StringTable::the_table()->table_size();
3412 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3413 if (process_strings) {
3414 StringTable::clear_parallel_claimed_index();
3415 }
3416 if (process_symbols) {
3417 SymbolTable::clear_parallel_claimed_index();
3418 }
3419 }
3420
3421 ~G1StringAndSymbolCleaningTask() {
3422 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3423 "claim value %d after unlink less than initial string table size %d",
3424 StringTable::parallel_claimed_index(), _initial_string_table_size);
3425 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3426 "claim value %d after unlink less than initial symbol table size %d",
3427 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3428
3429 log_info(gc, stringtable)(
3430 "Cleaned string and symbol table, "
3431 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3432 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3433 strings_processed(), strings_removed(),
3434 symbols_processed(), symbols_removed());
3435 }
3436
3437 void work(uint worker_id) {
3438 int strings_processed = 0;
3439 int strings_removed = 0;
3440 int symbols_processed = 0;
3441 int symbols_removed = 0;
3442 if (_process_strings) {
3443 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3444 Atomic::add(strings_processed, &_strings_processed);
3445 Atomic::add(strings_removed, &_strings_removed);
3446 }
3447 if (_process_symbols) {
3448 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3449 Atomic::add(symbols_processed, &_symbols_processed);
3450 Atomic::add(symbols_removed, &_symbols_removed);
3451 }
3452 if (_process_string_dedup) {
3453 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3454 }
3455 }
3456
3457 size_t strings_processed() const { return (size_t)_strings_processed; }
3458 size_t strings_removed() const { return (size_t)_strings_removed; }
3459
3460 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3461 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3462 };
3463
3464 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3465 private:
3466 static Monitor* _lock;
3467
3468 BoolObjectClosure* const _is_alive;
3469 const bool _unloading_occurred;
3470 const uint _num_workers;
3471
3472 // Variables used to claim nmethods.
3473 CompiledMethod* _first_nmethod;
3474 volatile CompiledMethod* _claimed_nmethod;
3475
3476 // The list of nmethods that need to be processed by the second pass.
3477 volatile CompiledMethod* _postponed_list;
3478 volatile uint _num_entered_barrier;
3479
3480 public:
3481 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3482 _is_alive(is_alive),
3483 _unloading_occurred(unloading_occurred),
3484 _num_workers(num_workers),
3485 _first_nmethod(NULL),
3486 _claimed_nmethod(NULL),
3487 _postponed_list(NULL),
3488 _num_entered_barrier(0)
3489 {
3490 CompiledMethod::increase_unloading_clock();
3491 // Get first alive nmethod
3492 CompiledMethodIterator iter = CompiledMethodIterator();
3493 if(iter.next_alive()) {
3494 _first_nmethod = iter.method();
3495 }
3496 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3497 }
3498
3499 ~G1CodeCacheUnloadingTask() {
3500 CodeCache::verify_clean_inline_caches();
3501
3502 CodeCache::set_needs_cache_clean(false);
3503 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3504
3505 CodeCache::verify_icholder_relocations();
3506 }
3507
3508 private:
3509 void add_to_postponed_list(CompiledMethod* nm) {
3510 CompiledMethod* old;
3511 do {
3512 old = (CompiledMethod*)_postponed_list;
3513 nm->set_unloading_next(old);
3514 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3515 }
3516
3517 void clean_nmethod(CompiledMethod* nm) {
3518 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3519
3520 if (postponed) {
3521 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3522 add_to_postponed_list(nm);
3523 }
3524
3525 // Mark that this thread has been cleaned/unloaded.
3526 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3527 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3528 }
3529
3530 void clean_nmethod_postponed(CompiledMethod* nm) {
3531 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3532 }
3533
3534 static const int MaxClaimNmethods = 16;
3535
3536 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3537 CompiledMethod* first;
3538 CompiledMethodIterator last;
3539
3540 do {
3541 *num_claimed_nmethods = 0;
3542
3543 first = (CompiledMethod*)_claimed_nmethod;
3544 last = CompiledMethodIterator(first);
3545
3546 if (first != NULL) {
3547
3548 for (int i = 0; i < MaxClaimNmethods; i++) {
3549 if (!last.next_alive()) {
3550 break;
3551 }
3552 claimed_nmethods[i] = last.method();
3553 (*num_claimed_nmethods)++;
3554 }
3555 }
3556
3557 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3558 }
3559
3560 CompiledMethod* claim_postponed_nmethod() {
3561 CompiledMethod* claim;
3562 CompiledMethod* next;
3563
3564 do {
3565 claim = (CompiledMethod*)_postponed_list;
3566 if (claim == NULL) {
3567 return NULL;
3568 }
3569
3570 next = claim->unloading_next();
3571
3572 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3573
3574 return claim;
3575 }
3576
3577 public:
3578 // Mark that we're done with the first pass of nmethod cleaning.
3579 void barrier_mark(uint worker_id) {
3580 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3581 _num_entered_barrier++;
3582 if (_num_entered_barrier == _num_workers) {
3583 ml.notify_all();
3584 }
3585 }
3586
3587 // See if we have to wait for the other workers to
3588 // finish their first-pass nmethod cleaning work.
3589 void barrier_wait(uint worker_id) {
3590 if (_num_entered_barrier < _num_workers) {
3591 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3592 while (_num_entered_barrier < _num_workers) {
3593 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3594 }
3595 }
3596 }
3597
3598 // Cleaning and unloading of nmethods. Some work has to be postponed
3599 // to the second pass, when we know which nmethods survive.
3600 void work_first_pass(uint worker_id) {
3601 // The first nmethods is claimed by the first worker.
3602 if (worker_id == 0 && _first_nmethod != NULL) {
3603 clean_nmethod(_first_nmethod);
3604 _first_nmethod = NULL;
3605 }
3606
3607 int num_claimed_nmethods;
3608 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3609
3610 while (true) {
3611 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3612
3613 if (num_claimed_nmethods == 0) {
3614 break;
3615 }
3616
3617 for (int i = 0; i < num_claimed_nmethods; i++) {
3618 clean_nmethod(claimed_nmethods[i]);
3619 }
3620 }
3621 }
3622
3623 void work_second_pass(uint worker_id) {
3624 CompiledMethod* nm;
3625 // Take care of postponed nmethods.
3626 while ((nm = claim_postponed_nmethod()) != NULL) {
3627 clean_nmethod_postponed(nm);
3628 }
3629 }
3630 };
3631
3632 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3633
3634 class G1KlassCleaningTask : public StackObj {
3635 BoolObjectClosure* _is_alive;
3636 volatile jint _clean_klass_tree_claimed;
3637 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3638
3639 public:
3640 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3641 _is_alive(is_alive),
3642 _clean_klass_tree_claimed(0),
3643 _klass_iterator() {
3644 }
3645
3646 private:
3647 bool claim_clean_klass_tree_task() {
3648 if (_clean_klass_tree_claimed) {
3649 return false;
3650 }
3651
3652 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3653 }
3654
3655 InstanceKlass* claim_next_klass() {
3656 Klass* klass;
3657 do {
3658 klass =_klass_iterator.next_klass();
3659 } while (klass != NULL && !klass->is_instance_klass());
3660
3661 // this can be null so don't call InstanceKlass::cast
3662 return static_cast<InstanceKlass*>(klass);
3663 }
3664
3665 public:
3666
3667 void clean_klass(InstanceKlass* ik) {
3668 ik->clean_weak_instanceklass_links(_is_alive);
3669 }
3670
3671 void work() {
3672 ResourceMark rm;
3673
3674 // One worker will clean the subklass/sibling klass tree.
3675 if (claim_clean_klass_tree_task()) {
3676 Klass::clean_subklass_tree(_is_alive);
3677 }
3678
3679 // All workers will help cleaning the classes,
3680 InstanceKlass* klass;
3681 while ((klass = claim_next_klass()) != NULL) {
3682 clean_klass(klass);
3683 }
3684 }
3685 };
3686
3687 class G1ResolvedMethodCleaningTask : public StackObj {
3688 BoolObjectClosure* _is_alive;
3689 volatile jint _resolved_method_task_claimed;
3690 public:
3691 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3692 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3693
3694 bool claim_resolved_method_task() {
3695 if (_resolved_method_task_claimed) {
3696 return false;
3697 }
3698 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3699 }
3700
3701 // These aren't big, one thread can do it all.
3702 void work() {
3703 if (claim_resolved_method_task()) {
3704 ResolvedMethodTable::unlink(_is_alive);
3705 }
3706 }
3707 };
3708
3709
3710 // To minimize the remark pause times, the tasks below are done in parallel.
3711 class G1ParallelCleaningTask : public AbstractGangTask {
3712 private:
3713 G1StringAndSymbolCleaningTask _string_symbol_task;
3714 G1CodeCacheUnloadingTask _code_cache_task;
3715 G1KlassCleaningTask _klass_cleaning_task;
3716 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3717
3718 public:
3719 // The constructor is run in the VMThread.
3720 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3721 AbstractGangTask("Parallel Cleaning"),
3722 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3723 _code_cache_task(num_workers, is_alive, unloading_occurred),
3724 _klass_cleaning_task(is_alive),
3725 _resolved_method_cleaning_task(is_alive) {
3726 }
3727
3728 // The parallel work done by all worker threads.
3729 void work(uint worker_id) {
3730 // Do first pass of code cache cleaning.
3731 _code_cache_task.work_first_pass(worker_id);
3732
3733 // Let the threads mark that the first pass is done.
3734 _code_cache_task.barrier_mark(worker_id);
3735
3736 // Clean the Strings and Symbols.
3737 _string_symbol_task.work(worker_id);
3738
3739 // Clean unreferenced things in the ResolvedMethodTable
3740 _resolved_method_cleaning_task.work();
3741
3742 // Wait for all workers to finish the first code cache cleaning pass.
3743 _code_cache_task.barrier_wait(worker_id);
3744
3745 // Do the second code cache cleaning work, which realize on
3746 // the liveness information gathered during the first pass.
3747 _code_cache_task.work_second_pass(worker_id);
3748
3749 // Clean all klasses that were not unloaded.
3750 _klass_cleaning_task.work();
3751 }
3752 };
3753
3754
3755 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3756 bool class_unloading_occurred) {
3757 uint n_workers = workers()->active_workers();
3758
3759 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3760 workers()->run_task(&g1_unlink_task);
3761 }
3762
3763 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3764 bool process_strings,
3765 bool process_symbols,
3766 bool process_string_dedup) {
3767 if (!process_strings && !process_symbols && !process_string_dedup) {
3768 // Nothing to clean.
3769 return;
3770 }
3771
3772 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3773 workers()->run_task(&g1_unlink_task);
3774
3775 }
3776
3777 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3778 private:
3779 DirtyCardQueueSet* _queue;
3780 G1CollectedHeap* _g1h;
3781 public:
3782 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3783 _queue(queue), _g1h(g1h) { }
3784
3785 virtual void work(uint worker_id) {
3786 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3787 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3788
3789 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3790 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3791
3792 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3793 }
3794 };
3795
3796 void G1CollectedHeap::redirty_logged_cards() {
3797 double redirty_logged_cards_start = os::elapsedTime();
3798
3799 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3800 dirty_card_queue_set().reset_for_par_iteration();
3801 workers()->run_task(&redirty_task);
3802
3803 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3804 dcq.merge_bufferlists(&dirty_card_queue_set());
3805 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3806
3807 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3808 }
3809
3810 // Weak Reference Processing support
3811
3812 // An always "is_alive" closure that is used to preserve referents.
3813 // If the object is non-null then it's alive. Used in the preservation
3814 // of referent objects that are pointed to by reference objects
3815 // discovered by the CM ref processor.
3816 class G1AlwaysAliveClosure: public BoolObjectClosure {
3817 G1CollectedHeap* _g1;
3818 public:
3819 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3820 bool do_object_b(oop p) {
3821 if (p != NULL) {
3822 return true;
3823 }
3824 return false;
3825 }
3826 };
3827
3828 bool G1STWIsAliveClosure::do_object_b(oop p) {
3829 // An object is reachable if it is outside the collection set,
3830 // or is inside and copied.
3831 return !_g1->is_in_cset(p) || p->is_forwarded();
3832 }
3833
3834 // Non Copying Keep Alive closure
3835 class G1KeepAliveClosure: public OopClosure {
3836 G1CollectedHeap* _g1;
3837 public:
3838 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3839 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3840 void do_oop(oop* p) {
3841 oop obj = *p;
3842 assert(obj != NULL, "the caller should have filtered out NULL values");
3843
3844 const InCSetState cset_state = _g1->in_cset_state(obj);
3845 if (!cset_state.is_in_cset_or_humongous()) {
3846 return;
3847 }
3848 if (cset_state.is_in_cset()) {
3849 assert( obj->is_forwarded(), "invariant" );
3850 *p = obj->forwardee();
3851 } else {
3852 assert(!obj->is_forwarded(), "invariant" );
3853 assert(cset_state.is_humongous(),
3854 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3855 _g1->set_humongous_is_live(obj);
3856 }
3857 }
3858 };
3859
3860 // Copying Keep Alive closure - can be called from both
3861 // serial and parallel code as long as different worker
3862 // threads utilize different G1ParScanThreadState instances
3863 // and different queues.
3864
3865 class G1CopyingKeepAliveClosure: public OopClosure {
3866 G1CollectedHeap* _g1h;
3867 OopClosure* _copy_non_heap_obj_cl;
3868 G1ParScanThreadState* _par_scan_state;
3869
3870 public:
3871 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3872 OopClosure* non_heap_obj_cl,
3873 G1ParScanThreadState* pss):
3874 _g1h(g1h),
3875 _copy_non_heap_obj_cl(non_heap_obj_cl),
3876 _par_scan_state(pss)
3877 {}
3878
3879 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3880 virtual void do_oop( oop* p) { do_oop_work(p); }
3881
3882 template <class T> void do_oop_work(T* p) {
3883 oop obj = oopDesc::load_decode_heap_oop(p);
3884
3885 if (_g1h->is_in_cset_or_humongous(obj)) {
3886 // If the referent object has been forwarded (either copied
3887 // to a new location or to itself in the event of an
3888 // evacuation failure) then we need to update the reference
3889 // field and, if both reference and referent are in the G1
3890 // heap, update the RSet for the referent.
3891 //
3892 // If the referent has not been forwarded then we have to keep
3893 // it alive by policy. Therefore we have copy the referent.
3894 //
3895 // If the reference field is in the G1 heap then we can push
3896 // on the PSS queue. When the queue is drained (after each
3897 // phase of reference processing) the object and it's followers
3898 // will be copied, the reference field set to point to the
3899 // new location, and the RSet updated. Otherwise we need to
3900 // use the the non-heap or metadata closures directly to copy
3901 // the referent object and update the pointer, while avoiding
3902 // updating the RSet.
3903
3904 if (_g1h->is_in_g1_reserved(p)) {
3905 _par_scan_state->push_on_queue(p);
3906 } else {
3907 assert(!Metaspace::contains((const void*)p),
3908 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3909 _copy_non_heap_obj_cl->do_oop(p);
3910 }
3911 }
3912 }
3913 };
3914
3915 // Serial drain queue closure. Called as the 'complete_gc'
3916 // closure for each discovered list in some of the
3917 // reference processing phases.
3918
3919 class G1STWDrainQueueClosure: public VoidClosure {
3920 protected:
3921 G1CollectedHeap* _g1h;
3922 G1ParScanThreadState* _par_scan_state;
3923
3924 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3925
3926 public:
3927 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3928 _g1h(g1h),
3929 _par_scan_state(pss)
3930 { }
3931
3932 void do_void() {
3933 G1ParScanThreadState* const pss = par_scan_state();
3934 pss->trim_queue();
3935 }
3936 };
3937
3938 // Parallel Reference Processing closures
3939
3940 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3941 // processing during G1 evacuation pauses.
3942
3943 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3944 private:
3945 G1CollectedHeap* _g1h;
3946 G1ParScanThreadStateSet* _pss;
3947 RefToScanQueueSet* _queues;
3948 WorkGang* _workers;
3949 uint _active_workers;
3950
3951 public:
3952 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3953 G1ParScanThreadStateSet* per_thread_states,
3954 WorkGang* workers,
3955 RefToScanQueueSet *task_queues,
3956 uint n_workers) :
3957 _g1h(g1h),
3958 _pss(per_thread_states),
3959 _queues(task_queues),
3960 _workers(workers),
3961 _active_workers(n_workers)
3962 {
3963 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3964 }
3965
3966 // Executes the given task using concurrent marking worker threads.
3967 virtual void execute(ProcessTask& task);
3968 virtual void execute(EnqueueTask& task);
3969 };
3970
3971 // Gang task for possibly parallel reference processing
3972
3973 class G1STWRefProcTaskProxy: public AbstractGangTask {
3974 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3975 ProcessTask& _proc_task;
3976 G1CollectedHeap* _g1h;
3977 G1ParScanThreadStateSet* _pss;
3978 RefToScanQueueSet* _task_queues;
3979 ParallelTaskTerminator* _terminator;
3980
3981 public:
3982 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3983 G1CollectedHeap* g1h,
3984 G1ParScanThreadStateSet* per_thread_states,
3985 RefToScanQueueSet *task_queues,
3986 ParallelTaskTerminator* terminator) :
3987 AbstractGangTask("Process reference objects in parallel"),
3988 _proc_task(proc_task),
3989 _g1h(g1h),
3990 _pss(per_thread_states),
3991 _task_queues(task_queues),
3992 _terminator(terminator)
3993 {}
3994
3995 virtual void work(uint worker_id) {
3996 // The reference processing task executed by a single worker.
3997 ResourceMark rm;
3998 HandleMark hm;
3999
4000 G1STWIsAliveClosure is_alive(_g1h);
4001
4002 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4003 pss->set_ref_processor(NULL);
4004
4005 // Keep alive closure.
4006 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4007
4008 // Complete GC closure
4009 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4010
4011 // Call the reference processing task's work routine.
4012 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4013
4014 // Note we cannot assert that the refs array is empty here as not all
4015 // of the processing tasks (specifically phase2 - pp2_work) execute
4016 // the complete_gc closure (which ordinarily would drain the queue) so
4017 // the queue may not be empty.
4018 }
4019 };
4020
4021 // Driver routine for parallel reference processing.
4022 // Creates an instance of the ref processing gang
4023 // task and has the worker threads execute it.
4024 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4025 assert(_workers != NULL, "Need parallel worker threads.");
4026
4027 ParallelTaskTerminator terminator(_active_workers, _queues);
4028 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4029
4030 _workers->run_task(&proc_task_proxy);
4031 }
4032
4033 // Gang task for parallel reference enqueueing.
4034
4035 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4036 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4037 EnqueueTask& _enq_task;
4038
4039 public:
4040 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4041 AbstractGangTask("Enqueue reference objects in parallel"),
4042 _enq_task(enq_task)
4043 { }
4044
4045 virtual void work(uint worker_id) {
4046 _enq_task.work(worker_id);
4047 }
4048 };
4049
4050 // Driver routine for parallel reference enqueueing.
4051 // Creates an instance of the ref enqueueing gang
4052 // task and has the worker threads execute it.
4053
4054 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4055 assert(_workers != NULL, "Need parallel worker threads.");
4056
4057 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4058
4059 _workers->run_task(&enq_task_proxy);
4060 }
4061
4062 // End of weak reference support closures
4063
4064 // Abstract task used to preserve (i.e. copy) any referent objects
4065 // that are in the collection set and are pointed to by reference
4066 // objects discovered by the CM ref processor.
4067
4068 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4069 protected:
4070 G1CollectedHeap* _g1h;
4071 G1ParScanThreadStateSet* _pss;
4072 RefToScanQueueSet* _queues;
4073 ParallelTaskTerminator _terminator;
4074 uint _n_workers;
4075
4076 public:
4077 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4078 AbstractGangTask("ParPreserveCMReferents"),
4079 _g1h(g1h),
4080 _pss(per_thread_states),
4081 _queues(task_queues),
4082 _terminator(workers, _queues),
4083 _n_workers(workers)
4084 {
4085 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4086 }
4087
4088 void work(uint worker_id) {
4089 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4090
4091 ResourceMark rm;
4092 HandleMark hm;
4093
4094 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4095 pss->set_ref_processor(NULL);
4096 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4097
4098 // Is alive closure
4099 G1AlwaysAliveClosure always_alive(_g1h);
4100
4101 // Copying keep alive closure. Applied to referent objects that need
4102 // to be copied.
4103 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4104
4105 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4106
4107 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4108 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4109
4110 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4111 // So this must be true - but assert just in case someone decides to
4112 // change the worker ids.
4113 assert(worker_id < limit, "sanity");
4114 assert(!rp->discovery_is_atomic(), "check this code");
4115
4116 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4117 for (uint idx = worker_id; idx < limit; idx += stride) {
4118 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4119
4120 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4121 while (iter.has_next()) {
4122 // Since discovery is not atomic for the CM ref processor, we
4123 // can see some null referent objects.
4124 iter.load_ptrs(DEBUG_ONLY(true));
4125 oop ref = iter.obj();
4126
4127 // This will filter nulls.
4128 if (iter.is_referent_alive()) {
4129 iter.make_referent_alive();
4130 }
4131 iter.move_to_next();
4132 }
4133 }
4134
4135 // Drain the queue - which may cause stealing
4136 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4137 drain_queue.do_void();
4138 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4139 assert(pss->queue_is_empty(), "should be");
4140 }
4141 };
4142
4143 void G1CollectedHeap::process_weak_jni_handles() {
4144 double ref_proc_start = os::elapsedTime();
4145
4146 G1STWIsAliveClosure is_alive(this);
4147 G1KeepAliveClosure keep_alive(this);
4148 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4149
4150 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4151 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4152 }
4153
4154 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4155 // Any reference objects, in the collection set, that were 'discovered'
4156 // by the CM ref processor should have already been copied (either by
4157 // applying the external root copy closure to the discovered lists, or
4158 // by following an RSet entry).
4159 //
4160 // But some of the referents, that are in the collection set, that these
4161 // reference objects point to may not have been copied: the STW ref
4162 // processor would have seen that the reference object had already
4163 // been 'discovered' and would have skipped discovering the reference,
4164 // but would not have treated the reference object as a regular oop.
4165 // As a result the copy closure would not have been applied to the
4166 // referent object.
4167 //
4168 // We need to explicitly copy these referent objects - the references
4169 // will be processed at the end of remarking.
4170 //
4171 // We also need to do this copying before we process the reference
4172 // objects discovered by the STW ref processor in case one of these
4173 // referents points to another object which is also referenced by an
4174 // object discovered by the STW ref processor.
4175 double preserve_cm_referents_time = 0.0;
4176
4177 // To avoid spawning task when there is no work to do, check that
4178 // a concurrent cycle is active and that some references have been
4179 // discovered.
4180 if (concurrent_mark()->cmThread()->during_cycle() &&
4181 ref_processor_cm()->has_discovered_references()) {
4182 double preserve_cm_referents_start = os::elapsedTime();
4183 uint no_of_gc_workers = workers()->active_workers();
4184 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4185 per_thread_states,
4186 no_of_gc_workers,
4187 _task_queues);
4188 workers()->run_task(&keep_cm_referents);
4189 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4190 }
4191
4192 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4193 }
4194
4195 // Weak Reference processing during an evacuation pause (part 1).
4196 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4197 double ref_proc_start = os::elapsedTime();
4198
4199 ReferenceProcessor* rp = _ref_processor_stw;
4200 assert(rp->discovery_enabled(), "should have been enabled");
4201
4202 // Closure to test whether a referent is alive.
4203 G1STWIsAliveClosure is_alive(this);
4204
4205 // Even when parallel reference processing is enabled, the processing
4206 // of JNI refs is serial and performed serially by the current thread
4207 // rather than by a worker. The following PSS will be used for processing
4208 // JNI refs.
4209
4210 // Use only a single queue for this PSS.
4211 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4212 pss->set_ref_processor(NULL);
4213 assert(pss->queue_is_empty(), "pre-condition");
4214
4215 // Keep alive closure.
4216 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4217
4218 // Serial Complete GC closure
4219 G1STWDrainQueueClosure drain_queue(this, pss);
4220
4221 // Setup the soft refs policy...
4222 rp->setup_policy(false);
4223
4224 ReferenceProcessorStats stats;
4225 if (!rp->processing_is_mt()) {
4226 // Serial reference processing...
4227 stats = rp->process_discovered_references(&is_alive,
4228 &keep_alive,
4229 &drain_queue,
4230 NULL,
4231 _gc_timer_stw);
4232 } else {
4233 uint no_of_gc_workers = workers()->active_workers();
4234
4235 // Parallel reference processing
4236 assert(no_of_gc_workers <= rp->max_num_q(),
4237 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4238 no_of_gc_workers, rp->max_num_q());
4239
4240 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4241 stats = rp->process_discovered_references(&is_alive,
4242 &keep_alive,
4243 &drain_queue,
4244 &par_task_executor,
4245 _gc_timer_stw);
4246 }
4247
4248 _gc_tracer_stw->report_gc_reference_stats(stats);
4249
4250 // We have completed copying any necessary live referent objects.
4251 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4252
4253 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4254 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4255 }
4256
4257 // Weak Reference processing during an evacuation pause (part 2).
4258 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4259 double ref_enq_start = os::elapsedTime();
4260
4261 ReferenceProcessor* rp = _ref_processor_stw;
4262 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4263
4264 // Now enqueue any remaining on the discovered lists on to
4265 // the pending list.
4266 if (!rp->processing_is_mt()) {
4267 // Serial reference processing...
4268 rp->enqueue_discovered_references();
4269 } else {
4270 // Parallel reference enqueueing
4271
4272 uint n_workers = workers()->active_workers();
4273
4274 assert(n_workers <= rp->max_num_q(),
4275 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4276 n_workers, rp->max_num_q());
4277
4278 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4279 rp->enqueue_discovered_references(&par_task_executor);
4280 }
4281
4282 rp->verify_no_references_recorded();
4283 assert(!rp->discovery_enabled(), "should have been disabled");
4284
4285 // FIXME
4286 // CM's reference processing also cleans up the string and symbol tables.
4287 // Should we do that here also? We could, but it is a serial operation
4288 // and could significantly increase the pause time.
4289
4290 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4291 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4292 }
4293
4294 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4295 double merge_pss_time_start = os::elapsedTime();
4296 per_thread_states->flush();
4297 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4298 }
4299
4300 void G1CollectedHeap::pre_evacuate_collection_set() {
4301 _expand_heap_after_alloc_failure = true;
4302 _evacuation_failed = false;
4303
4304 // Disable the hot card cache.
4305 _hot_card_cache->reset_hot_cache_claimed_index();
4306 _hot_card_cache->set_use_cache(false);
4307
4308 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4309 _preserved_marks_set.assert_empty();
4310
4311 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4312
4313 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4314 if (collector_state()->during_initial_mark_pause()) {
4315 double start_clear_claimed_marks = os::elapsedTime();
4316
4317 ClassLoaderDataGraph::clear_claimed_marks();
4318
4319 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4320 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4321 }
4322 }
4323
4324 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4325 // Should G1EvacuationFailureALot be in effect for this GC?
4326 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4327
4328 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4329
4330 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4331
4332 double start_par_time_sec = os::elapsedTime();
4333 double end_par_time_sec;
4334
4335 {
4336 const uint n_workers = workers()->active_workers();
4337 G1RootProcessor root_processor(this, n_workers);
4338 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4339
4340 print_termination_stats_hdr();
4341
4342 workers()->run_task(&g1_par_task);
4343 end_par_time_sec = os::elapsedTime();
4344
4345 // Closing the inner scope will execute the destructor
4346 // for the G1RootProcessor object. We record the current
4347 // elapsed time before closing the scope so that time
4348 // taken for the destructor is NOT included in the
4349 // reported parallel time.
4350 }
4351
4352 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4353 phase_times->record_par_time(par_time_ms);
4354
4355 double code_root_fixup_time_ms =
4356 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4357 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4358 }
4359
4360 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4361 // Process any discovered reference objects - we have
4362 // to do this _before_ we retire the GC alloc regions
4363 // as we may have to copy some 'reachable' referent
4364 // objects (and their reachable sub-graphs) that were
4365 // not copied during the pause.
4366 if (g1_policy()->should_process_references()) {
4367 preserve_cm_referents(per_thread_states);
4368 process_discovered_references(per_thread_states);
4369 } else {
4370 ref_processor_stw()->verify_no_references_recorded();
4371 process_weak_jni_handles();
4372 }
4373
4374 if (G1StringDedup::is_enabled()) {
4375 double fixup_start = os::elapsedTime();
4376
4377 G1STWIsAliveClosure is_alive(this);
4378 G1KeepAliveClosure keep_alive(this);
4379 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4380
4381 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4382 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4383 }
4384
4385 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4386
4387 if (evacuation_failed()) {
4388 restore_after_evac_failure();
4389
4390 // Reset the G1EvacuationFailureALot counters and flags
4391 // Note: the values are reset only when an actual
4392 // evacuation failure occurs.
4393 NOT_PRODUCT(reset_evacuation_should_fail();)
4394 }
4395
4396 _preserved_marks_set.assert_empty();
4397
4398 // Enqueue any remaining references remaining on the STW
4399 // reference processor's discovered lists. We need to do
4400 // this after the card table is cleaned (and verified) as
4401 // the act of enqueueing entries on to the pending list
4402 // will log these updates (and dirty their associated
4403 // cards). We need these updates logged to update any
4404 // RSets.
4405 if (g1_policy()->should_process_references()) {
4406 enqueue_discovered_references(per_thread_states);
4407 } else {
4408 g1_policy()->phase_times()->record_ref_enq_time(0);
4409 }
4410
4411 _allocator->release_gc_alloc_regions(evacuation_info);
4412
4413 merge_per_thread_state_info(per_thread_states);
4414
4415 // Reset and re-enable the hot card cache.
4416 // Note the counts for the cards in the regions in the
4417 // collection set are reset when the collection set is freed.
4418 _hot_card_cache->reset_hot_cache();
4419 _hot_card_cache->set_use_cache(true);
4420
4421 purge_code_root_memory();
4422
4423 redirty_logged_cards();
4424 #if defined(COMPILER2) || INCLUDE_JVMCI
4425 double start = os::elapsedTime();
4426 DerivedPointerTable::update_pointers();
4427 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4428 #endif
4429 g1_policy()->print_age_table();
4430 }
4431
4432 void G1CollectedHeap::record_obj_copy_mem_stats() {
4433 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4434
4435 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4436 create_g1_evac_summary(&_old_evac_stats));
4437 }
4438
4439 void G1CollectedHeap::free_region(HeapRegion* hr,
4440 FreeRegionList* free_list,
4441 bool skip_remset,
4442 bool skip_hot_card_cache,
4443 bool locked) {
4444 assert(!hr->is_free(), "the region should not be free");
4445 assert(!hr->is_empty(), "the region should not be empty");
4446 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4447 assert(free_list != NULL, "pre-condition");
4448
4449 if (G1VerifyBitmaps) {
4450 MemRegion mr(hr->bottom(), hr->end());
4451 concurrent_mark()->clearRangePrevBitmap(mr);
4452 }
4453
4454 // Clear the card counts for this region.
4455 // Note: we only need to do this if the region is not young
4456 // (since we don't refine cards in young regions).
4457 if (!skip_hot_card_cache && !hr->is_young()) {
4458 _hot_card_cache->reset_card_counts(hr);
4459 }
4460 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4461 free_list->add_ordered(hr);
4462 }
4463
4464 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4465 FreeRegionList* free_list,
4466 bool skip_remset) {
4467 assert(hr->is_humongous(), "this is only for humongous regions");
4468 assert(free_list != NULL, "pre-condition");
4469 hr->clear_humongous();
4470 free_region(hr, free_list, skip_remset);
4471 }
4472
4473 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4474 const uint humongous_regions_removed) {
4475 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4476 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4477 _old_set.bulk_remove(old_regions_removed);
4478 _humongous_set.bulk_remove(humongous_regions_removed);
4479 }
4480
4481 }
4482
4483 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4484 assert(list != NULL, "list can't be null");
4485 if (!list->is_empty()) {
4486 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4487 _hrm.insert_list_into_free_list(list);
4488 }
4489 }
4490
4491 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4492 decrease_used(bytes);
4493 }
4494
4495 class G1ParScrubRemSetTask: public AbstractGangTask {
4496 protected:
4497 G1RemSet* _g1rs;
4498 HeapRegionClaimer _hrclaimer;
4499
4500 public:
4501 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4502 AbstractGangTask("G1 ScrubRS"),
4503 _g1rs(g1_rs),
4504 _hrclaimer(num_workers) {
4505 }
4506
4507 void work(uint worker_id) {
4508 _g1rs->scrub(worker_id, &_hrclaimer);
4509 }
4510 };
4511
4512 void G1CollectedHeap::scrub_rem_set() {
4513 uint num_workers = workers()->active_workers();
4514 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4515 workers()->run_task(&g1_par_scrub_rs_task);
4516 }
4517
4518 class G1FreeCollectionSetTask : public AbstractGangTask {
4519 private:
4520
4521 // Closure applied to all regions in the collection set to do work that needs to
4522 // be done serially in a single thread.
4523 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4524 private:
4525 EvacuationInfo* _evacuation_info;
4526 const size_t* _surviving_young_words;
4527
4528 // Bytes used in successfully evacuated regions before the evacuation.
4529 size_t _before_used_bytes;
4530 // Bytes used in unsucessfully evacuated regions before the evacuation
4531 size_t _after_used_bytes;
4532
4533 size_t _bytes_allocated_in_old_since_last_gc;
4534
4535 size_t _failure_used_words;
4536 size_t _failure_waste_words;
4537
4538 FreeRegionList _local_free_list;
4539 public:
4540 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4541 HeapRegionClosure(),
4542 _evacuation_info(evacuation_info),
4543 _surviving_young_words(surviving_young_words),
4544 _before_used_bytes(0),
4545 _after_used_bytes(0),
4546 _bytes_allocated_in_old_since_last_gc(0),
4547 _failure_used_words(0),
4548 _failure_waste_words(0),
4549 _local_free_list("Local Region List for CSet Freeing") {
4550 }
4551
4552 virtual bool doHeapRegion(HeapRegion* r) {
4553 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4554
4555 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4556 g1h->clear_in_cset(r);
4557
4558 if (r->is_young()) {
4559 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4560 "Young index %d is wrong for region %u of type %s with %u young regions",
4561 r->young_index_in_cset(),
4562 r->hrm_index(),
4563 r->get_type_str(),
4564 g1h->collection_set()->young_region_length());
4565 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4566 r->record_surv_words_in_group(words_survived);
4567 }
4568
4569 if (!r->evacuation_failed()) {
4570 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4571 _before_used_bytes += r->used();
4572 g1h->free_region(r,
4573 &_local_free_list,
4574 true, /* skip_remset */
4575 true, /* skip_hot_card_cache */
4576 true /* locked */);
4577 } else {
4578 r->uninstall_surv_rate_group();
4579 r->set_young_index_in_cset(-1);
4580 r->set_evacuation_failed(false);
4581 // When moving a young gen region to old gen, we "allocate" that whole region
4582 // there. This is in addition to any already evacuated objects. Notify the
4583 // policy about that.
4584 // Old gen regions do not cause an additional allocation: both the objects
4585 // still in the region and the ones already moved are accounted for elsewhere.
4586 if (r->is_young()) {
4587 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4588 }
4589 // The region is now considered to be old.
4590 r->set_old();
4591 // Do some allocation statistics accounting. Regions that failed evacuation
4592 // are always made old, so there is no need to update anything in the young
4593 // gen statistics, but we need to update old gen statistics.
4594 size_t used_words = r->marked_bytes() / HeapWordSize;
4595
4596 _failure_used_words += used_words;
4597 _failure_waste_words += HeapRegion::GrainWords - used_words;
4598
4599 g1h->old_set_add(r);
4600 _after_used_bytes += r->used();
4601 }
4602 return false;
4603 }
4604
4605 void complete_work() {
4606 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4607
4608 _evacuation_info->set_regions_freed(_local_free_list.length());
4609 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4610
4611 g1h->prepend_to_freelist(&_local_free_list);
4612 g1h->decrement_summary_bytes(_before_used_bytes);
4613
4614 G1Policy* policy = g1h->g1_policy();
4615 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4616
4617 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4618 }
4619 };
4620
4621 G1CollectionSet* _collection_set;
4622 G1SerialFreeCollectionSetClosure _cl;
4623 const size_t* _surviving_young_words;
4624
4625 size_t _rs_lengths;
4626
4627 volatile jint _serial_work_claim;
4628
4629 struct WorkItem {
4630 uint region_idx;
4631 bool is_young;
4632 bool evacuation_failed;
4633
4634 WorkItem(HeapRegion* r) {
4635 region_idx = r->hrm_index();
4636 is_young = r->is_young();
4637 evacuation_failed = r->evacuation_failed();
4638 }
4639 };
4640
4641 volatile size_t _parallel_work_claim;
4642 size_t _num_work_items;
4643 WorkItem* _work_items;
4644
4645 void do_serial_work() {
4646 // Need to grab the lock to be allowed to modify the old region list.
4647 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4648 _collection_set->iterate(&_cl);
4649 }
4650
4651 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4652 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4653
4654 HeapRegion* r = g1h->region_at(region_idx);
4655 assert(!g1h->is_on_master_free_list(r), "sanity");
4656
4657 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4658
4659 if (!is_young) {
4660 g1h->_hot_card_cache->reset_card_counts(r);
4661 }
4662
4663 if (!evacuation_failed) {
4664 r->rem_set()->clear_locked();
4665 }
4666 }
4667
4668 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4669 private:
4670 size_t _cur_idx;
4671 WorkItem* _work_items;
4672 public:
4673 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4674
4675 virtual bool doHeapRegion(HeapRegion* r) {
4676 _work_items[_cur_idx++] = WorkItem(r);
4677 return false;
4678 }
4679 };
4680
4681 void prepare_work() {
4682 G1PrepareFreeCollectionSetClosure cl(_work_items);
4683 _collection_set->iterate(&cl);
4684 }
4685
4686 void complete_work() {
4687 _cl.complete_work();
4688
4689 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4690 policy->record_max_rs_lengths(_rs_lengths);
4691 policy->cset_regions_freed();
4692 }
4693 public:
4694 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4695 AbstractGangTask("G1 Free Collection Set"),
4696 _cl(evacuation_info, surviving_young_words),
4697 _collection_set(collection_set),
4698 _surviving_young_words(surviving_young_words),
4699 _serial_work_claim(0),
4700 _rs_lengths(0),
4701 _parallel_work_claim(0),
4702 _num_work_items(collection_set->region_length()),
4703 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4704 prepare_work();
4705 }
4706
4707 ~G1FreeCollectionSetTask() {
4708 complete_work();
4709 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4710 }
4711
4712 // Chunk size for work distribution. The chosen value has been determined experimentally
4713 // to be a good tradeoff between overhead and achievable parallelism.
4714 static uint chunk_size() { return 32; }
4715
4716 virtual void work(uint worker_id) {
4717 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4718
4719 // Claim serial work.
4720 if (_serial_work_claim == 0) {
4721 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4722 if (value == 0) {
4723 double serial_time = os::elapsedTime();
4724 do_serial_work();
4725 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4726 }
4727 }
4728
4729 // Start parallel work.
4730 double young_time = 0.0;
4731 bool has_young_time = false;
4732 double non_young_time = 0.0;
4733 bool has_non_young_time = false;
4734
4735 while (true) {
4736 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4737 size_t cur = end - chunk_size();
4738
4739 if (cur >= _num_work_items) {
4740 break;
4741 }
4742
4743 double start_time = os::elapsedTime();
4744
4745 end = MIN2(end, _num_work_items);
4746
4747 for (; cur < end; cur++) {
4748 bool is_young = _work_items[cur].is_young;
4749
4750 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4751
4752 double end_time = os::elapsedTime();
4753 double time_taken = end_time - start_time;
4754 if (is_young) {
4755 young_time += time_taken;
4756 has_young_time = true;
4757 } else {
4758 non_young_time += time_taken;
4759 has_non_young_time = true;
4760 }
4761 start_time = end_time;
4762 }
4763 }
4764
4765 if (has_young_time) {
4766 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4767 }
4768 if (has_non_young_time) {
4769 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4770 }
4771 }
4772 };
4773
4774 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4775 _eden.clear();
4776
4777 double free_cset_start_time = os::elapsedTime();
4778
4779 {
4780 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4781 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4782
4783 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4784
4785 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4786 cl.name(),
4787 num_workers,
4788 _collection_set.region_length());
4789 workers()->run_task(&cl, num_workers);
4790 }
4791 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4792
4793 collection_set->clear();
4794 }
4795
4796 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4797 private:
4798 FreeRegionList* _free_region_list;
4799 HeapRegionSet* _proxy_set;
4800 uint _humongous_objects_reclaimed;
4801 uint _humongous_regions_reclaimed;
4802 size_t _freed_bytes;
4803 public:
4804
4805 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4806 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4807 }
4808
4809 virtual bool doHeapRegion(HeapRegion* r) {
4810 if (!r->is_starts_humongous()) {
4811 return false;
4812 }
4813
4814 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4815
4816 oop obj = (oop)r->bottom();
4817 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4818
4819 // The following checks whether the humongous object is live are sufficient.
4820 // The main additional check (in addition to having a reference from the roots
4821 // or the young gen) is whether the humongous object has a remembered set entry.
4822 //
4823 // A humongous object cannot be live if there is no remembered set for it
4824 // because:
4825 // - there can be no references from within humongous starts regions referencing
4826 // the object because we never allocate other objects into them.
4827 // (I.e. there are no intra-region references that may be missed by the
4828 // remembered set)
4829 // - as soon there is a remembered set entry to the humongous starts region
4830 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4831 // until the end of a concurrent mark.
4832 //
4833 // It is not required to check whether the object has been found dead by marking
4834 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4835 // all objects allocated during that time are considered live.
4836 // SATB marking is even more conservative than the remembered set.
4837 // So if at this point in the collection there is no remembered set entry,
4838 // nobody has a reference to it.
4839 // At the start of collection we flush all refinement logs, and remembered sets
4840 // are completely up-to-date wrt to references to the humongous object.
4841 //
4842 // Other implementation considerations:
4843 // - never consider object arrays at this time because they would pose
4844 // considerable effort for cleaning up the the remembered sets. This is
4845 // required because stale remembered sets might reference locations that
4846 // are currently allocated into.
4847 uint region_idx = r->hrm_index();
4848 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4849 !r->rem_set()->is_empty()) {
4850 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",
4851 region_idx,
4852 (size_t)obj->size() * HeapWordSize,
4853 p2i(r->bottom()),
4854 r->rem_set()->occupied(),
4855 r->rem_set()->strong_code_roots_list_length(),
4856 next_bitmap->isMarked(r->bottom()),
4857 g1h->is_humongous_reclaim_candidate(region_idx),
4858 obj->is_typeArray()
4859 );
4860 return false;
4861 }
4862
4863 guarantee(obj->is_typeArray(),
4864 "Only eagerly reclaiming type arrays is supported, but the object "
4865 PTR_FORMAT " is not.", p2i(r->bottom()));
4866
4867 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",
4868 region_idx,
4869 (size_t)obj->size() * HeapWordSize,
4870 p2i(r->bottom()),
4871 r->rem_set()->occupied(),
4872 r->rem_set()->strong_code_roots_list_length(),
4873 next_bitmap->isMarked(r->bottom()),
4874 g1h->is_humongous_reclaim_candidate(region_idx),
4875 obj->is_typeArray()
4876 );
4877
4878 // Need to clear mark bit of the humongous object if already set.
4879 if (next_bitmap->isMarked(r->bottom())) {
4880 next_bitmap->clear(r->bottom());
4881 }
4882 _humongous_objects_reclaimed++;
4883 do {
4884 HeapRegion* next = g1h->next_region_in_humongous(r);
4885 _freed_bytes += r->used();
4886 r->set_containing_set(NULL);
4887 _humongous_regions_reclaimed++;
4888 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4889 r = next;
4890 } while (r != NULL);
4891
4892 return false;
4893 }
4894
4895 uint humongous_objects_reclaimed() {
4896 return _humongous_objects_reclaimed;
4897 }
4898
4899 uint humongous_regions_reclaimed() {
4900 return _humongous_regions_reclaimed;
4901 }
4902
4903 size_t bytes_freed() const {
4904 return _freed_bytes;
4905 }
4906 };
4907
4908 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4909 assert_at_safepoint(true);
4910
4911 if (!G1EagerReclaimHumongousObjects ||
4912 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4913 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4914 return;
4915 }
4916
4917 double start_time = os::elapsedTime();
4918
4919 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4920
4921 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4922 heap_region_iterate(&cl);
4923
4924 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4925
4926 G1HRPrinter* hrp = hr_printer();
4927 if (hrp->is_active()) {
4928 FreeRegionListIterator iter(&local_cleanup_list);
4929 while (iter.more_available()) {
4930 HeapRegion* hr = iter.get_next();
4931 hrp->cleanup(hr);
4932 }
4933 }
4934
4935 prepend_to_freelist(&local_cleanup_list);
4936 decrement_summary_bytes(cl.bytes_freed());
4937
4938 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4939 cl.humongous_objects_reclaimed());
4940 }
4941
4942 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4943 public:
4944 virtual bool doHeapRegion(HeapRegion* r) {
4945 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4946 G1CollectedHeap::heap()->clear_in_cset(r);
4947 r->set_young_index_in_cset(-1);
4948 return false;
4949 }
4950 };
4951
4952 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4953 G1AbandonCollectionSetClosure cl;
4954 collection_set->iterate(&cl);
4955
4956 collection_set->clear();
4957 collection_set->stop_incremental_building();
4958 }
4959
4960 void G1CollectedHeap::set_free_regions_coming() {
4961 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4962
4963 assert(!free_regions_coming(), "pre-condition");
4964 _free_regions_coming = true;
4965 }
4966
4967 void G1CollectedHeap::reset_free_regions_coming() {
4968 assert(free_regions_coming(), "pre-condition");
4969
4970 {
4971 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4972 _free_regions_coming = false;
4973 SecondaryFreeList_lock->notify_all();
4974 }
4975
4976 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4977 }
4978
4979 void G1CollectedHeap::wait_while_free_regions_coming() {
4980 // Most of the time we won't have to wait, so let's do a quick test
4981 // first before we take the lock.
4982 if (!free_regions_coming()) {
4983 return;
4984 }
4985
4986 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4987
4988 {
4989 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4990 while (free_regions_coming()) {
4991 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4992 }
4993 }
4994
4995 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4996 }
4997
4998 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4999 return _allocator->is_retained_old_region(hr);
5000 }
5001
5002 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5003 _eden.add(hr);
5004 _g1_policy->set_region_eden(hr);
5005 }
5006
5007 #ifdef ASSERT
5008
5009 class NoYoungRegionsClosure: public HeapRegionClosure {
5010 private:
5011 bool _success;
5012 public:
5013 NoYoungRegionsClosure() : _success(true) { }
5014 bool doHeapRegion(HeapRegion* r) {
5015 if (r->is_young()) {
5016 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5017 p2i(r->bottom()), p2i(r->end()));
5018 _success = false;
5019 }
5020 return false;
5021 }
5022 bool success() { return _success; }
5023 };
5024
5025 bool G1CollectedHeap::check_young_list_empty() {
5026 bool ret = (young_regions_count() == 0);
5027
5028 NoYoungRegionsClosure closure;
5029 heap_region_iterate(&closure);
5030 ret = ret && closure.success();
5031
5032 return ret;
5033 }
5034
5035 #endif // ASSERT
5036
5037 class TearDownRegionSetsClosure : public HeapRegionClosure {
5038 private:
5039 HeapRegionSet *_old_set;
5040
5041 public:
5042 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5043
5044 bool doHeapRegion(HeapRegion* r) {
5045 if (r->is_old()) {
5046 _old_set->remove(r);
5047 } else if(r->is_young()) {
5048 r->uninstall_surv_rate_group();
5049 } else {
5050 // We ignore free regions, we'll empty the free list afterwards.
5051 // We ignore humongous regions, we're not tearing down the
5052 // humongous regions set.
5053 assert(r->is_free() || r->is_humongous(),
5054 "it cannot be another type");
5055 }
5056 return false;
5057 }
5058
5059 ~TearDownRegionSetsClosure() {
5060 assert(_old_set->is_empty(), "post-condition");
5061 }
5062 };
5063
5064 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5065 assert_at_safepoint(true /* should_be_vm_thread */);
5066
5067 if (!free_list_only) {
5068 TearDownRegionSetsClosure cl(&_old_set);
5069 heap_region_iterate(&cl);
5070
5071 // Note that emptying the _young_list is postponed and instead done as
5072 // the first step when rebuilding the regions sets again. The reason for
5073 // this is that during a full GC string deduplication needs to know if
5074 // a collected region was young or old when the full GC was initiated.
5075 }
5076 _hrm.remove_all_free_regions();
5077 }
5078
5079 void G1CollectedHeap::increase_used(size_t bytes) {
5080 _summary_bytes_used += bytes;
5081 }
5082
5083 void G1CollectedHeap::decrease_used(size_t bytes) {
5084 assert(_summary_bytes_used >= bytes,
5085 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5086 _summary_bytes_used, bytes);
5087 _summary_bytes_used -= bytes;
5088 }
5089
5090 void G1CollectedHeap::set_used(size_t bytes) {
5091 _summary_bytes_used = bytes;
5092 }
5093
5094 class RebuildRegionSetsClosure : public HeapRegionClosure {
5095 private:
5096 bool _free_list_only;
5097 HeapRegionSet* _old_set;
5098 HeapRegionManager* _hrm;
5099 size_t _total_used;
5100
5101 public:
5102 RebuildRegionSetsClosure(bool free_list_only,
5103 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5104 _free_list_only(free_list_only),
5105 _old_set(old_set), _hrm(hrm), _total_used(0) {
5106 assert(_hrm->num_free_regions() == 0, "pre-condition");
5107 if (!free_list_only) {
5108 assert(_old_set->is_empty(), "pre-condition");
5109 }
5110 }
5111
5112 bool doHeapRegion(HeapRegion* r) {
5113 if (r->is_empty()) {
5114 // Add free regions to the free list
5115 r->set_free();
5116 r->set_allocation_context(AllocationContext::system());
5117 _hrm->insert_into_free_list(r);
5118 } else if (!_free_list_only) {
5119
5120 if (r->is_humongous()) {
5121 // We ignore humongous regions. We left the humongous set unchanged.
5122 } else {
5123 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5124 // We now consider all regions old, so register as such. Leave
5125 // archive regions set that way, however, while still adding
5126 // them to the old set.
5127 if (!r->is_archive()) {
5128 r->set_old();
5129 }
5130 _old_set->add(r);
5131 }
5132 _total_used += r->used();
5133 }
5134
5135 return false;
5136 }
5137
5138 size_t total_used() {
5139 return _total_used;
5140 }
5141 };
5142
5143 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5144 assert_at_safepoint(true /* should_be_vm_thread */);
5145
5146 if (!free_list_only) {
5147 _eden.clear();
5148 _survivor.clear();
5149 }
5150
5151 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5152 heap_region_iterate(&cl);
5153
5154 if (!free_list_only) {
5155 set_used(cl.total_used());
5156 if (_archive_allocator != NULL) {
5157 _archive_allocator->clear_used();
5158 }
5159 }
5160 assert(used_unlocked() == recalculate_used(),
5161 "inconsistent used_unlocked(), "
5162 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5163 used_unlocked(), recalculate_used());
5164 }
5165
5166 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5167 _refine_cte_cl->set_concurrent(concurrent);
5168 }
5169
5170 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5171 HeapRegion* hr = heap_region_containing(p);
5172 return hr->is_in(p);
5173 }
5174
5175 // Methods for the mutator alloc region
5176
5177 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5178 bool force) {
5179 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5180 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5181 if (force || should_allocate) {
5182 HeapRegion* new_alloc_region = new_region(word_size,
5183 false /* is_old */,
5184 false /* do_expand */);
5185 if (new_alloc_region != NULL) {
5186 set_region_short_lived_locked(new_alloc_region);
5187 _hr_printer.alloc(new_alloc_region, !should_allocate);
5188 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5189 return new_alloc_region;
5190 }
5191 }
5192 return NULL;
5193 }
5194
5195 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5196 size_t allocated_bytes) {
5197 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5198 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5199
5200 collection_set()->add_eden_region(alloc_region);
5201 increase_used(allocated_bytes);
5202 _hr_printer.retire(alloc_region);
5203 // We update the eden sizes here, when the region is retired,
5204 // instead of when it's allocated, since this is the point that its
5205 // used space has been recored in _summary_bytes_used.
5206 g1mm()->update_eden_size();
5207 }
5208
5209 // Methods for the GC alloc regions
5210
5211 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5212 if (dest.is_old()) {
5213 return true;
5214 } else {
5215 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5216 }
5217 }
5218
5219 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5220 assert(FreeList_lock->owned_by_self(), "pre-condition");
5221
5222 if (!has_more_regions(dest)) {
5223 return NULL;
5224 }
5225
5226 const bool is_survivor = dest.is_young();
5227
5228 HeapRegion* new_alloc_region = new_region(word_size,
5229 !is_survivor,
5230 true /* do_expand */);
5231 if (new_alloc_region != NULL) {
5232 // We really only need to do this for old regions given that we
5233 // should never scan survivors. But it doesn't hurt to do it
5234 // for survivors too.
5235 new_alloc_region->record_timestamp();
5236 if (is_survivor) {
5237 new_alloc_region->set_survivor();
5238 _survivor.add(new_alloc_region);
5239 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5240 } else {
5241 new_alloc_region->set_old();
5242 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5243 }
5244 _hr_printer.alloc(new_alloc_region);
5245 bool during_im = collector_state()->during_initial_mark_pause();
5246 new_alloc_region->note_start_of_copying(during_im);
5247 return new_alloc_region;
5248 }
5249 return NULL;
5250 }
5251
5252 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5253 size_t allocated_bytes,
5254 InCSetState dest) {
5255 bool during_im = collector_state()->during_initial_mark_pause();
5256 alloc_region->note_end_of_copying(during_im);
5257 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5258 if (dest.is_old()) {
5259 _old_set.add(alloc_region);
5260 }
5261 _hr_printer.retire(alloc_region);
5262 }
5263
5264 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5265 bool expanded = false;
5266 uint index = _hrm.find_highest_free(&expanded);
5267
5268 if (index != G1_NO_HRM_INDEX) {
5269 if (expanded) {
5270 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5271 HeapRegion::GrainWords * HeapWordSize);
5272 }
5273 _hrm.allocate_free_regions_starting_at(index, 1);
5274 return region_at(index);
5275 }
5276 return NULL;
5277 }
5278
5279 // Optimized nmethod scanning
5280
5281 class RegisterNMethodOopClosure: public OopClosure {
5282 G1CollectedHeap* _g1h;
5283 nmethod* _nm;
5284
5285 template <class T> void do_oop_work(T* p) {
5286 T heap_oop = oopDesc::load_heap_oop(p);
5287 if (!oopDesc::is_null(heap_oop)) {
5288 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5289 HeapRegion* hr = _g1h->heap_region_containing(obj);
5290 assert(!hr->is_continues_humongous(),
5291 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5292 " starting at " HR_FORMAT,
5293 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5294
5295 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5296 hr->add_strong_code_root_locked(_nm);
5297 }
5298 }
5299
5300 public:
5301 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5302 _g1h(g1h), _nm(nm) {}
5303
5304 void do_oop(oop* p) { do_oop_work(p); }
5305 void do_oop(narrowOop* p) { do_oop_work(p); }
5306 };
5307
5308 class UnregisterNMethodOopClosure: public OopClosure {
5309 G1CollectedHeap* _g1h;
5310 nmethod* _nm;
5311
5312 template <class T> void do_oop_work(T* p) {
5313 T heap_oop = oopDesc::load_heap_oop(p);
5314 if (!oopDesc::is_null(heap_oop)) {
5315 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5316 HeapRegion* hr = _g1h->heap_region_containing(obj);
5317 assert(!hr->is_continues_humongous(),
5318 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5319 " starting at " HR_FORMAT,
5320 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5321
5322 hr->remove_strong_code_root(_nm);
5323 }
5324 }
5325
5326 public:
5327 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5328 _g1h(g1h), _nm(nm) {}
5329
5330 void do_oop(oop* p) { do_oop_work(p); }
5331 void do_oop(narrowOop* p) { do_oop_work(p); }
5332 };
5333
5334 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5335 CollectedHeap::register_nmethod(nm);
5336
5337 guarantee(nm != NULL, "sanity");
5338 RegisterNMethodOopClosure reg_cl(this, nm);
5339 nm->oops_do(®_cl);
5340 }
5341
5342 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5343 CollectedHeap::unregister_nmethod(nm);
5344
5345 guarantee(nm != NULL, "sanity");
5346 UnregisterNMethodOopClosure reg_cl(this, nm);
5347 nm->oops_do(®_cl, true);
5348 }
5349
5350 void G1CollectedHeap::purge_code_root_memory() {
5351 double purge_start = os::elapsedTime();
5352 G1CodeRootSet::purge();
5353 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5354 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5355 }
5356
5357 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5358 G1CollectedHeap* _g1h;
5359
5360 public:
5361 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5362 _g1h(g1h) {}
5363
5364 void do_code_blob(CodeBlob* cb) {
5365 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5366 if (nm == NULL) {
5367 return;
5368 }
5369
5370 if (ScavengeRootsInCode) {
5371 _g1h->register_nmethod(nm);
5372 }
5373 }
5374 };
5375
5376 void G1CollectedHeap::rebuild_strong_code_roots() {
5377 RebuildStrongCodeRootClosure blob_cl(this);
5378 CodeCache::blobs_do(&blob_cl);
5379 }