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