1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullGCScope.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1SerialFullCollector.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 G1CardTable* _g1_ct;
103
104 HeapRegion* region_for_card(jbyte* card_ptr) const {
105 return _g1h->heap_region_containing(_g1_ct->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_ct(g1h->g1_card_table()) { }
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 = G1CardTable::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 // Private methods.
152
153 HeapRegion*
154 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
155 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
156 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
157 if (!_secondary_free_list.is_empty()) {
158 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
159 "secondary_free_list has %u entries",
160 _secondary_free_list.length());
161 // It looks as if there are free regions available on the
162 // secondary_free_list. Let's move them to the free_list and try
163 // again to allocate from it.
164 append_secondary_free_list();
165
166 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
167 "empty we should have moved at least one entry to the free_list");
168 HeapRegion* res = _hrm.allocate_free_region(is_old);
169 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
170 "allocated " HR_FORMAT " from secondary_free_list",
171 HR_FORMAT_PARAMS(res));
172 return res;
173 }
174
175 // Wait here until we get notified either when (a) there are no
176 // more free regions coming or (b) some regions have been moved on
177 // the secondary_free_list.
178 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
179 }
180
181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
182 "could not allocate from secondary_free_list");
183 return NULL;
184 }
185
186 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
187 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
188 "the only time we use this to allocate a humongous region is "
189 "when we are allocating a single humongous region");
190
191 HeapRegion* res;
192 if (G1StressConcRegionFreeing) {
193 if (!_secondary_free_list.is_empty()) {
194 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
195 "forced to look at the secondary_free_list");
196 res = new_region_try_secondary_free_list(is_old);
197 if (res != NULL) {
198 return res;
199 }
200 }
201 }
202
203 res = _hrm.allocate_free_region(is_old);
204
205 if (res == NULL) {
206 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
207 "res == NULL, trying the secondary_free_list");
208 res = new_region_try_secondary_free_list(is_old);
209 }
210 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
211 // Currently, only attempts to allocate GC alloc regions set
212 // do_expand to true. So, we should only reach here during a
213 // safepoint. If this assumption changes we might have to
214 // reconsider the use of _expand_heap_after_alloc_failure.
215 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
216
217 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
218 word_size * HeapWordSize);
219
220 if (expand(word_size * HeapWordSize)) {
221 // Given that expand() succeeded in expanding the heap, and we
222 // always expand the heap by an amount aligned to the heap
223 // region size, the free list should in theory not be empty.
224 // In either case allocate_free_region() will check for NULL.
225 res = _hrm.allocate_free_region(is_old);
226 } else {
227 _expand_heap_after_alloc_failure = false;
228 }
229 }
230 return res;
231 }
232
233 HeapWord*
234 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
235 uint num_regions,
236 size_t word_size,
237 AllocationContext_t context) {
238 assert(first != G1_NO_HRM_INDEX, "pre-condition");
239 assert(is_humongous(word_size), "word_size should be humongous");
240 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
241
242 // Index of last region in the series.
243 uint last = first + num_regions - 1;
244
245 // We need to initialize the region(s) we just discovered. This is
246 // a bit tricky given that it can happen concurrently with
247 // refinement threads refining cards on these regions and
248 // potentially wanting to refine the BOT as they are scanning
249 // those cards (this can happen shortly after a cleanup; see CR
250 // 6991377). So we have to set up the region(s) carefully and in
251 // a specific order.
252
253 // The word size sum of all the regions we will allocate.
254 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
255 assert(word_size <= word_size_sum, "sanity");
256
257 // This will be the "starts humongous" region.
258 HeapRegion* first_hr = region_at(first);
259 // The header of the new object will be placed at the bottom of
260 // the first region.
261 HeapWord* new_obj = first_hr->bottom();
262 // This will be the new top of the new object.
263 HeapWord* obj_top = new_obj + word_size;
264
265 // First, we need to zero the header of the space that we will be
266 // allocating. When we update top further down, some refinement
267 // threads might try to scan the region. By zeroing the header we
268 // ensure that any thread that will try to scan the region will
269 // come across the zero klass word and bail out.
270 //
271 // NOTE: It would not have been correct to have used
272 // CollectedHeap::fill_with_object() and make the space look like
273 // an int array. The thread that is doing the allocation will
274 // later update the object header to a potentially different array
275 // type and, for a very short period of time, the klass and length
276 // fields will be inconsistent. This could cause a refinement
277 // thread to calculate the object size incorrectly.
278 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
279
280 // Next, pad out the unused tail of the last region with filler
281 // objects, for improved usage accounting.
282 // How many words we use for filler objects.
283 size_t word_fill_size = word_size_sum - word_size;
284
285 // How many words memory we "waste" which cannot hold a filler object.
286 size_t words_not_fillable = 0;
287
288 if (word_fill_size >= min_fill_size()) {
289 fill_with_objects(obj_top, word_fill_size);
290 } else if (word_fill_size > 0) {
291 // We have space to fill, but we cannot fit an object there.
292 words_not_fillable = word_fill_size;
293 word_fill_size = 0;
294 }
295
296 // We will set up the first region as "starts humongous". This
297 // will also update the BOT covering all the regions to reflect
298 // that there is a single object that starts at the bottom of the
299 // first region.
300 first_hr->set_starts_humongous(obj_top, word_fill_size);
301 first_hr->set_allocation_context(context);
302 // Then, if there are any, we will set up the "continues
303 // humongous" regions.
304 HeapRegion* hr = NULL;
305 for (uint i = first + 1; i <= last; ++i) {
306 hr = region_at(i);
307 hr->set_continues_humongous(first_hr);
308 hr->set_allocation_context(context);
309 }
310
311 // Up to this point no concurrent thread would have been able to
312 // do any scanning on any region in this series. All the top
313 // fields still point to bottom, so the intersection between
314 // [bottom,top] and [card_start,card_end] will be empty. Before we
315 // update the top fields, we'll do a storestore to make sure that
316 // no thread sees the update to top before the zeroing of the
317 // object header and the BOT initialization.
318 OrderAccess::storestore();
319
320 // Now, we will update the top fields of the "continues humongous"
321 // regions except the last one.
322 for (uint i = first; i < last; ++i) {
323 hr = region_at(i);
324 hr->set_top(hr->end());
325 }
326
327 hr = region_at(last);
328 // If we cannot fit a filler object, we must set top to the end
329 // of the humongous object, otherwise we cannot iterate the heap
330 // and the BOT will not be complete.
331 hr->set_top(hr->end() - words_not_fillable);
332
333 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
334 "obj_top should be in last region");
335
336 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
337
338 assert(words_not_fillable == 0 ||
339 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
340 "Miscalculation in humongous allocation");
341
342 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
343
344 for (uint i = first; i <= last; ++i) {
345 hr = region_at(i);
346 _humongous_set.add(hr);
347 _hr_printer.alloc(hr);
348 }
349
350 return new_obj;
351 }
352
353 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
354 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
355 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
356 }
357
358 // If could fit into free regions w/o expansion, try.
359 // Otherwise, if can expand, do so.
360 // Otherwise, if using ex regions might help, try with ex given back.
361 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
363
364 _verifier->verify_region_sets_optional();
365
366 uint first = G1_NO_HRM_INDEX;
367 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
368
369 if (obj_regions == 1) {
370 // Only one region to allocate, try to use a fast path by directly allocating
371 // from the free lists. Do not try to expand here, we will potentially do that
372 // later.
373 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
374 if (hr != NULL) {
375 first = hr->hrm_index();
376 }
377 } else {
378 // We can't allocate humongous regions spanning more than one region while
379 // cleanupComplete() is running, since some of the regions we find to be
380 // empty might not yet be added to the free list. It is not straightforward
381 // to know in which list they are on so that we can remove them. We only
382 // need to do this if we need to allocate more than one region to satisfy the
383 // current humongous allocation request. If we are only allocating one region
384 // we use the one-region region allocation code (see above), that already
385 // potentially waits for regions from the secondary free list.
386 wait_while_free_regions_coming();
387 append_secondary_free_list_if_not_empty_with_lock();
388
389 // Policy: Try only empty regions (i.e. already committed first). Maybe we
390 // are lucky enough to find some.
391 first = _hrm.find_contiguous_only_empty(obj_regions);
392 if (first != G1_NO_HRM_INDEX) {
393 _hrm.allocate_free_regions_starting_at(first, obj_regions);
394 }
395 }
396
397 if (first == G1_NO_HRM_INDEX) {
398 // Policy: We could not find enough regions for the humongous object in the
399 // free list. Look through the heap to find a mix of free and uncommitted regions.
400 // If so, try expansion.
401 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
402 if (first != G1_NO_HRM_INDEX) {
403 // We found something. Make sure these regions are committed, i.e. expand
404 // the heap. Alternatively we could do a defragmentation GC.
405 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
406 word_size * HeapWordSize);
407
408 _hrm.expand_at(first, obj_regions, workers());
409 g1_policy()->record_new_heap_size(num_regions());
410
411 #ifdef ASSERT
412 for (uint i = first; i < first + obj_regions; ++i) {
413 HeapRegion* hr = region_at(i);
414 assert(hr->is_free(), "sanity");
415 assert(hr->is_empty(), "sanity");
416 assert(is_on_master_free_list(hr), "sanity");
417 }
418 #endif
419 _hrm.allocate_free_regions_starting_at(first, obj_regions);
420 } else {
421 // Policy: Potentially trigger a defragmentation GC.
422 }
423 }
424
425 HeapWord* result = NULL;
426 if (first != G1_NO_HRM_INDEX) {
427 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
428 word_size, context);
429 assert(result != NULL, "it should always return a valid result");
430
431 // A successful humongous object allocation changes the used space
432 // information of the old generation so we need to recalculate the
433 // sizes and update the jstat counters here.
434 g1mm()->update_sizes();
435 }
436
437 _verifier->verify_region_sets_optional();
438
439 return result;
440 }
441
442 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
443 assert_heap_not_locked_and_not_at_safepoint();
444 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
445
446 uint dummy_gc_count_before;
447 uint dummy_gclocker_retry_count = 0;
448 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
449 }
450
451 HeapWord*
452 G1CollectedHeap::mem_allocate(size_t word_size,
453 bool* gc_overhead_limit_was_exceeded) {
454 assert_heap_not_locked_and_not_at_safepoint();
455
456 // Loop until the allocation is satisfied, or unsatisfied after GC.
457 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
458 uint gc_count_before;
459
460 HeapWord* result = NULL;
461 if (!is_humongous(word_size)) {
462 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
463 } else {
464 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
465 }
466 if (result != NULL) {
467 return result;
468 }
469
470 // Create the garbage collection operation...
471 VM_G1CollectForAllocation op(gc_count_before, word_size);
472 op.set_allocation_context(AllocationContext::current());
473
474 // ...and get the VM thread to execute it.
475 VMThread::execute(&op);
476
477 if (op.prologue_succeeded() && op.pause_succeeded()) {
478 // If the operation was successful we'll return the result even
479 // if it is NULL. If the allocation attempt failed immediately
480 // after a Full GC, it's unlikely we'll be able to allocate now.
481 HeapWord* result = op.result();
482 if (result != NULL && !is_humongous(word_size)) {
483 // Allocations that take place on VM operations do not do any
484 // card dirtying and we have to do it here. We only have to do
485 // this for non-humongous allocations, though.
486 dirty_young_block(result, word_size);
487 }
488 return result;
489 } else {
490 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
491 return NULL;
492 }
493 assert(op.result() == NULL,
494 "the result should be NULL if the VM op did not succeed");
495 }
496
497 // Give a warning if we seem to be looping forever.
498 if ((QueuedAllocationWarningCount > 0) &&
499 (try_count % QueuedAllocationWarningCount == 0)) {
500 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
501 }
502 }
503
504 ShouldNotReachHere();
505 return NULL;
506 }
507
508 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
509 AllocationContext_t context,
510 uint* gc_count_before_ret,
511 uint* gclocker_retry_count_ret) {
512 // Make sure you read the note in attempt_allocation_humongous().
513
514 assert_heap_not_locked_and_not_at_safepoint();
515 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
516 "be called for humongous allocation requests");
517
518 // We should only get here after the first-level allocation attempt
519 // (attempt_allocation()) failed to allocate.
520
521 // We will loop until a) we manage to successfully perform the
522 // allocation or b) we successfully schedule a collection which
523 // fails to perform the allocation. b) is the only case when we'll
524 // return NULL.
525 HeapWord* result = NULL;
526 for (int try_count = 1; /* we'll return */; try_count += 1) {
527 bool should_try_gc;
528 uint gc_count_before;
529
530 {
531 MutexLockerEx x(Heap_lock);
532 result = _allocator->attempt_allocation_locked(word_size, context);
533 if (result != NULL) {
534 return result;
535 }
536
537 if (GCLocker::is_active_and_needs_gc()) {
538 if (g1_policy()->can_expand_young_list()) {
539 // No need for an ergo verbose message here,
540 // can_expand_young_list() does this when it returns true.
541 result = _allocator->attempt_allocation_force(word_size, context);
542 if (result != NULL) {
543 return result;
544 }
545 }
546 should_try_gc = false;
547 } else {
548 // The GCLocker may not be active but the GCLocker initiated
549 // GC may not yet have been performed (GCLocker::needs_gc()
550 // returns true). In this case we do not try this GC and
551 // wait until the GCLocker initiated GC is performed, and
552 // then retry the allocation.
553 if (GCLocker::needs_gc()) {
554 should_try_gc = false;
555 } else {
556 // Read the GC count while still holding the Heap_lock.
557 gc_count_before = total_collections();
558 should_try_gc = true;
559 }
560 }
561 }
562
563 if (should_try_gc) {
564 bool succeeded;
565 result = do_collection_pause(word_size, gc_count_before, &succeeded,
566 GCCause::_g1_inc_collection_pause);
567 if (result != NULL) {
568 assert(succeeded, "only way to get back a non-NULL result");
569 return result;
570 }
571
572 if (succeeded) {
573 // If we get here we successfully scheduled a collection which
574 // failed to allocate. No point in trying to allocate
575 // further. We'll just return NULL.
576 MutexLockerEx x(Heap_lock);
577 *gc_count_before_ret = total_collections();
578 return NULL;
579 }
580 } else {
581 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
582 MutexLockerEx x(Heap_lock);
583 *gc_count_before_ret = total_collections();
584 return NULL;
585 }
586 // The GCLocker is either active or the GCLocker initiated
587 // GC has not yet been performed. Stall until it is and
588 // then retry the allocation.
589 GCLocker::stall_until_clear();
590 (*gclocker_retry_count_ret) += 1;
591 }
592
593 // We can reach here if we were unsuccessful in scheduling a
594 // collection (because another thread beat us to it) or if we were
595 // stalled due to the GC locker. In either can we should retry the
596 // allocation attempt in case another thread successfully
597 // performed a collection and reclaimed enough space. We do the
598 // first attempt (without holding the Heap_lock) here and the
599 // follow-on attempt will be at the start of the next loop
600 // iteration (after taking the Heap_lock).
601 result = _allocator->attempt_allocation(word_size, context);
602 if (result != NULL) {
603 return result;
604 }
605
606 // Give a warning if we seem to be looping forever.
607 if ((QueuedAllocationWarningCount > 0) &&
608 (try_count % QueuedAllocationWarningCount == 0)) {
609 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
610 "retries %d times", try_count);
611 }
612 }
613
614 ShouldNotReachHere();
615 return NULL;
616 }
617
618 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
619 assert_at_safepoint(true /* should_be_vm_thread */);
620 if (_archive_allocator == NULL) {
621 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
622 }
623 }
624
625 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
626 // Allocations in archive regions cannot be of a size that would be considered
627 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
628 // may be different at archive-restore time.
629 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
630 }
631
632 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
633 assert_at_safepoint(true /* should_be_vm_thread */);
634 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
635 if (is_archive_alloc_too_large(word_size)) {
636 return NULL;
637 }
638 return _archive_allocator->archive_mem_allocate(word_size);
639 }
640
641 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
642 size_t end_alignment_in_bytes) {
643 assert_at_safepoint(true /* should_be_vm_thread */);
644 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
645
646 // Call complete_archive to do the real work, filling in the MemRegion
647 // array with the archive regions.
648 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
649 delete _archive_allocator;
650 _archive_allocator = NULL;
651 }
652
653 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
654 assert(ranges != NULL, "MemRegion array NULL");
655 assert(count != 0, "No MemRegions provided");
656 MemRegion reserved = _hrm.reserved();
657 for (size_t i = 0; i < count; i++) {
658 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
659 return false;
660 }
661 }
662 return true;
663 }
664
665 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
666 size_t count,
667 bool open) {
668 assert(!is_init_completed(), "Expect to be called at JVM init time");
669 assert(ranges != NULL, "MemRegion array NULL");
670 assert(count != 0, "No MemRegions provided");
671 MutexLockerEx x(Heap_lock);
672
673 MemRegion reserved = _hrm.reserved();
674 HeapWord* prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // Temporarily disable pretouching of heap pages. This interface is used
678 // when mmap'ing archived heap data in, so pre-touching is wasted.
679 FlagSetting fs(AlwaysPreTouch, false);
680
681 // Enable archive object checking used by G1MarkSweep. We have to let it know
682 // about each archive range, so that objects in those ranges aren't marked.
683 G1ArchiveAllocator::enable_archive_object_check();
684
685 // For each specified MemRegion range, allocate the corresponding G1
686 // regions and mark them as archive regions. We expect the ranges
687 // in ascending starting address order, without overlap.
688 for (size_t i = 0; i < count; i++) {
689 MemRegion curr_range = ranges[i];
690 HeapWord* start_address = curr_range.start();
691 size_t word_size = curr_range.word_size();
692 HeapWord* last_address = curr_range.last();
693 size_t commits = 0;
694
695 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
696 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
697 p2i(start_address), p2i(last_address));
698 guarantee(start_address > prev_last_addr,
699 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
700 p2i(start_address), p2i(prev_last_addr));
701 prev_last_addr = last_address;
702
703 // Check for ranges that start in the same G1 region in which the previous
704 // range ended, and adjust the start address so we don't try to allocate
705 // the same region again. If the current range is entirely within that
706 // region, skip it, just adjusting the recorded top.
707 HeapRegion* start_region = _hrm.addr_to_region(start_address);
708 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
709 start_address = start_region->end();
710 if (start_address > last_address) {
711 increase_used(word_size * HeapWordSize);
712 start_region->set_top(last_address + 1);
713 continue;
714 }
715 start_region->set_top(start_address);
716 curr_range = MemRegion(start_address, last_address + 1);
717 start_region = _hrm.addr_to_region(start_address);
718 }
719
720 // Perform the actual region allocation, exiting if it fails.
721 // Then note how much new space we have allocated.
722 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
723 return false;
724 }
725 increase_used(word_size * HeapWordSize);
726 if (commits != 0) {
727 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
728 HeapRegion::GrainWords * HeapWordSize * commits);
729
730 }
731
732 // Mark each G1 region touched by the range as archive, add it to
733 // the old set, and set the allocation context and top.
734 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
735 HeapRegion* last_region = _hrm.addr_to_region(last_address);
736 prev_last_region = last_region;
737
738 while (curr_region != NULL) {
739 assert(curr_region->is_empty() && !curr_region->is_pinned(),
740 "Region already in use (index %u)", curr_region->hrm_index());
741 curr_region->set_allocation_context(AllocationContext::system());
742 if (open) {
743 curr_region->set_open_archive();
744 } else {
745 curr_region->set_closed_archive();
746 }
747 _hr_printer.alloc(curr_region);
748 _old_set.add(curr_region);
749 HeapWord* top;
750 HeapRegion* next_region;
751 if (curr_region != last_region) {
752 top = curr_region->end();
753 next_region = _hrm.next_region_in_heap(curr_region);
754 } else {
755 top = last_address + 1;
756 next_region = NULL;
757 }
758 curr_region->set_top(top);
759 curr_region->set_first_dead(top);
760 curr_region->set_end_of_live(top);
761 curr_region = next_region;
762 }
763
764 // Notify mark-sweep of the archive
765 G1ArchiveAllocator::set_range_archive(curr_range, open);
766 }
767 return true;
768 }
769
770 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
771 assert(!is_init_completed(), "Expect to be called at JVM init time");
772 assert(ranges != NULL, "MemRegion array NULL");
773 assert(count != 0, "No MemRegions provided");
774 MemRegion reserved = _hrm.reserved();
775 HeapWord *prev_last_addr = NULL;
776 HeapRegion* prev_last_region = NULL;
777
778 // For each MemRegion, create filler objects, if needed, in the G1 regions
779 // that contain the address range. The address range actually within the
780 // MemRegion will not be modified. That is assumed to have been initialized
781 // elsewhere, probably via an mmap of archived heap data.
782 MutexLockerEx x(Heap_lock);
783 for (size_t i = 0; i < count; i++) {
784 HeapWord* start_address = ranges[i].start();
785 HeapWord* last_address = ranges[i].last();
786
787 assert(reserved.contains(start_address) && reserved.contains(last_address),
788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
789 p2i(start_address), p2i(last_address));
790 assert(start_address > prev_last_addr,
791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
792 p2i(start_address), p2i(prev_last_addr));
793
794 HeapRegion* start_region = _hrm.addr_to_region(start_address);
795 HeapRegion* last_region = _hrm.addr_to_region(last_address);
796 HeapWord* bottom_address = start_region->bottom();
797
798 // Check for a range beginning in the same region in which the
799 // previous one ended.
800 if (start_region == prev_last_region) {
801 bottom_address = prev_last_addr + 1;
802 }
803
804 // Verify that the regions were all marked as archive regions by
805 // alloc_archive_regions.
806 HeapRegion* curr_region = start_region;
807 while (curr_region != NULL) {
808 guarantee(curr_region->is_archive(),
809 "Expected archive region at index %u", curr_region->hrm_index());
810 if (curr_region != last_region) {
811 curr_region = _hrm.next_region_in_heap(curr_region);
812 } else {
813 curr_region = NULL;
814 }
815 }
816
817 prev_last_addr = last_address;
818 prev_last_region = last_region;
819
820 // Fill the memory below the allocated range with dummy object(s),
821 // if the region bottom does not match the range start, or if the previous
822 // range ended within the same G1 region, and there is a gap.
823 if (start_address != bottom_address) {
824 size_t fill_size = pointer_delta(start_address, bottom_address);
825 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
826 increase_used(fill_size * HeapWordSize);
827 }
828 }
829 }
830
831 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
832 uint* gc_count_before_ret,
833 uint* gclocker_retry_count_ret) {
834 assert_heap_not_locked_and_not_at_safepoint();
835 assert(!is_humongous(word_size), "attempt_allocation() should not "
836 "be called for humongous allocation requests");
837
838 AllocationContext_t context = AllocationContext::current();
839 HeapWord* result = _allocator->attempt_allocation(word_size, context);
840
841 if (result == NULL) {
842 result = attempt_allocation_slow(word_size,
843 context,
844 gc_count_before_ret,
845 gclocker_retry_count_ret);
846 }
847 assert_heap_not_locked();
848 if (result != NULL) {
849 dirty_young_block(result, word_size);
850 }
851 return result;
852 }
853
854 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
855 assert(!is_init_completed(), "Expect to be called at JVM init time");
856 assert(ranges != NULL, "MemRegion array NULL");
857 assert(count != 0, "No MemRegions provided");
858 MemRegion reserved = _hrm.reserved();
859 HeapWord* prev_last_addr = NULL;
860 HeapRegion* prev_last_region = NULL;
861 size_t size_used = 0;
862 size_t uncommitted_regions = 0;
863
864 // For each Memregion, free the G1 regions that constitute it, and
865 // notify mark-sweep that the range is no longer to be considered 'archive.'
866 MutexLockerEx x(Heap_lock);
867 for (size_t i = 0; i < count; i++) {
868 HeapWord* start_address = ranges[i].start();
869 HeapWord* last_address = ranges[i].last();
870
871 assert(reserved.contains(start_address) && reserved.contains(last_address),
872 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
873 p2i(start_address), p2i(last_address));
874 assert(start_address > prev_last_addr,
875 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
876 p2i(start_address), p2i(prev_last_addr));
877 size_used += ranges[i].byte_size();
878 prev_last_addr = last_address;
879
880 HeapRegion* start_region = _hrm.addr_to_region(start_address);
881 HeapRegion* last_region = _hrm.addr_to_region(last_address);
882
883 // Check for ranges that start in the same G1 region in which the previous
884 // range ended, and adjust the start address so we don't try to free
885 // the same region again. If the current range is entirely within that
886 // region, skip it.
887 if (start_region == prev_last_region) {
888 start_address = start_region->end();
889 if (start_address > last_address) {
890 continue;
891 }
892 start_region = _hrm.addr_to_region(start_address);
893 }
894 prev_last_region = last_region;
895
896 // After verifying that each region was marked as an archive region by
897 // alloc_archive_regions, set it free and empty and uncommit it.
898 HeapRegion* curr_region = start_region;
899 while (curr_region != NULL) {
900 guarantee(curr_region->is_archive(),
901 "Expected archive region at index %u", curr_region->hrm_index());
902 uint curr_index = curr_region->hrm_index();
903 _old_set.remove(curr_region);
904 curr_region->set_free();
905 curr_region->set_top(curr_region->bottom());
906 if (curr_region != last_region) {
907 curr_region = _hrm.next_region_in_heap(curr_region);
908 } else {
909 curr_region = NULL;
910 }
911 _hrm.shrink_at(curr_index, 1);
912 uncommitted_regions++;
913 }
914
915 // Notify mark-sweep that this is no longer an archive range.
916 G1ArchiveAllocator::set_range_archive(ranges[i], false);
917 }
918
919 if (uncommitted_regions != 0) {
920 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
921 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
922 }
923 decrease_used(size_used);
924 }
925
926 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
927 uint* gc_count_before_ret,
928 uint* gclocker_retry_count_ret) {
929 // The structure of this method has a lot of similarities to
930 // attempt_allocation_slow(). The reason these two were not merged
931 // into a single one is that such a method would require several "if
932 // allocation is not humongous do this, otherwise do that"
933 // conditional paths which would obscure its flow. In fact, an early
934 // version of this code did use a unified method which was harder to
935 // follow and, as a result, it had subtle bugs that were hard to
936 // track down. So keeping these two methods separate allows each to
937 // be more readable. It will be good to keep these two in sync as
938 // much as possible.
939
940 assert_heap_not_locked_and_not_at_safepoint();
941 assert(is_humongous(word_size), "attempt_allocation_humongous() "
942 "should only be called for humongous allocations");
943
944 // Humongous objects can exhaust the heap quickly, so we should check if we
945 // need to start a marking cycle at each humongous object allocation. We do
946 // the check before we do the actual allocation. The reason for doing it
947 // before the allocation is that we avoid having to keep track of the newly
948 // allocated memory while we do a GC.
949 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
950 word_size)) {
951 collect(GCCause::_g1_humongous_allocation);
952 }
953
954 // We will loop until a) we manage to successfully perform the
955 // allocation or b) we successfully schedule a collection which
956 // fails to perform the allocation. b) is the only case when we'll
957 // return NULL.
958 HeapWord* result = NULL;
959 for (int try_count = 1; /* we'll return */; try_count += 1) {
960 bool should_try_gc;
961 uint gc_count_before;
962
963 {
964 MutexLockerEx x(Heap_lock);
965
966 // Given that humongous objects are not allocated in young
967 // regions, we'll first try to do the allocation without doing a
968 // collection hoping that there's enough space in the heap.
969 result = humongous_obj_allocate(word_size, AllocationContext::current());
970 if (result != NULL) {
971 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
972 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
973 return result;
974 }
975
976 if (GCLocker::is_active_and_needs_gc()) {
977 should_try_gc = false;
978 } else {
979 // The GCLocker may not be active but the GCLocker initiated
980 // GC may not yet have been performed (GCLocker::needs_gc()
981 // returns true). In this case we do not try this GC and
982 // wait until the GCLocker initiated GC is performed, and
983 // then retry the allocation.
984 if (GCLocker::needs_gc()) {
985 should_try_gc = false;
986 } else {
987 // Read the GC count while still holding the Heap_lock.
988 gc_count_before = total_collections();
989 should_try_gc = true;
990 }
991 }
992 }
993
994 if (should_try_gc) {
995 // If we failed to allocate the humongous object, we should try to
996 // do a collection pause (if we're allowed) in case it reclaims
997 // enough space for the allocation to succeed after the pause.
998
999 bool succeeded;
1000 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1001 GCCause::_g1_humongous_allocation);
1002 if (result != NULL) {
1003 assert(succeeded, "only way to get back a non-NULL result");
1004 return result;
1005 }
1006
1007 if (succeeded) {
1008 // If we get here we successfully scheduled a collection which
1009 // failed to allocate. No point in trying to allocate
1010 // further. We'll just return NULL.
1011 MutexLockerEx x(Heap_lock);
1012 *gc_count_before_ret = total_collections();
1013 return NULL;
1014 }
1015 } else {
1016 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1017 MutexLockerEx x(Heap_lock);
1018 *gc_count_before_ret = total_collections();
1019 return NULL;
1020 }
1021 // The GCLocker is either active or the GCLocker initiated
1022 // GC has not yet been performed. Stall until it is and
1023 // then retry the allocation.
1024 GCLocker::stall_until_clear();
1025 (*gclocker_retry_count_ret) += 1;
1026 }
1027
1028 // We can reach here if we were unsuccessful in scheduling a
1029 // collection (because another thread beat us to it) or if we were
1030 // stalled due to the GC locker. In either can we should retry the
1031 // allocation attempt in case another thread successfully
1032 // performed a collection and reclaimed enough space. Give a
1033 // warning if we seem to be looping forever.
1034
1035 if ((QueuedAllocationWarningCount > 0) &&
1036 (try_count % QueuedAllocationWarningCount == 0)) {
1037 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1038 "retries %d times", try_count);
1039 }
1040 }
1041
1042 ShouldNotReachHere();
1043 return NULL;
1044 }
1045
1046 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1047 AllocationContext_t context,
1048 bool expect_null_mutator_alloc_region) {
1049 assert_at_safepoint(true /* should_be_vm_thread */);
1050 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1051 "the current alloc region was unexpectedly found to be non-NULL");
1052
1053 if (!is_humongous(word_size)) {
1054 return _allocator->attempt_allocation_locked(word_size, context);
1055 } else {
1056 HeapWord* result = humongous_obj_allocate(word_size, context);
1057 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1058 collector_state()->set_initiate_conc_mark_if_possible(true);
1059 }
1060 return result;
1061 }
1062
1063 ShouldNotReachHere();
1064 }
1065
1066 class PostCompactionPrinterClosure: public HeapRegionClosure {
1067 private:
1068 G1HRPrinter* _hr_printer;
1069 public:
1070 bool doHeapRegion(HeapRegion* hr) {
1071 assert(!hr->is_young(), "not expecting to find young regions");
1072 _hr_printer->post_compaction(hr);
1073 return false;
1074 }
1075
1076 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1077 : _hr_printer(hr_printer) { }
1078 };
1079
1080 void G1CollectedHeap::print_hrm_post_compaction() {
1081 if (_hr_printer.is_active()) {
1082 PostCompactionPrinterClosure cl(hr_printer());
1083 heap_region_iterate(&cl);
1084 }
1085
1086 }
1087
1088 void G1CollectedHeap::abort_concurrent_cycle() {
1089 // Note: When we have a more flexible GC logging framework that
1090 // allows us to add optional attributes to a GC log record we
1091 // could consider timing and reporting how long we wait in the
1092 // following two methods.
1093 wait_while_free_regions_coming();
1094 // If we start the compaction before the CM threads finish
1095 // scanning the root regions we might trip them over as we'll
1096 // be moving objects / updating references. So let's wait until
1097 // they are done. By telling them to abort, they should complete
1098 // early.
1099 _cm->root_regions()->abort();
1100 _cm->root_regions()->wait_until_scan_finished();
1101 append_secondary_free_list_if_not_empty_with_lock();
1102
1103 // Disable discovery and empty the discovered lists
1104 // for the CM ref processor.
1105 ref_processor_cm()->disable_discovery();
1106 ref_processor_cm()->abandon_partial_discovery();
1107 ref_processor_cm()->verify_no_references_recorded();
1108
1109 // Abandon current iterations of concurrent marking and concurrent
1110 // refinement, if any are in progress.
1111 concurrent_mark()->abort();
1112 }
1113
1114 void G1CollectedHeap::prepare_heap_for_full_collection() {
1115 // Make sure we'll choose a new allocation region afterwards.
1116 _allocator->release_mutator_alloc_region();
1117 _allocator->abandon_gc_alloc_regions();
1118 g1_rem_set()->cleanupHRRS();
1119
1120 // We may have added regions to the current incremental collection
1121 // set between the last GC or pause and now. We need to clear the
1122 // incremental collection set and then start rebuilding it afresh
1123 // after this full GC.
1124 abandon_collection_set(collection_set());
1125
1126 tear_down_region_sets(false /* free_list_only */);
1127 collector_state()->set_gcs_are_young(true);
1128 }
1129
1130 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1131 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1132 assert(used() == recalculate_used(), "Should be equal");
1133 _verifier->verify_region_sets_optional();
1134 _verifier->verify_before_gc();
1135 _verifier->check_bitmaps("Full GC Start");
1136 }
1137
1138 void G1CollectedHeap::prepare_heap_for_mutators() {
1139 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1140 ClassLoaderDataGraph::purge();
1141 MetaspaceAux::verify_metrics();
1142
1143 // Prepare heap for normal collections.
1144 assert(num_free_regions() == 0, "we should not have added any free regions");
1145 rebuild_region_sets(false /* free_list_only */);
1146 abort_refinement();
1147 resize_if_necessary_after_full_collection();
1148
1149 // Rebuild the strong code root lists for each region
1150 rebuild_strong_code_roots();
1151
1152 // Start a new incremental collection set for the next pause
1153 start_new_collection_set();
1154
1155 _allocator->init_mutator_alloc_region();
1156
1157 // Post collection state updates.
1158 MetaspaceGC::compute_new_size();
1159 }
1160
1161 void G1CollectedHeap::abort_refinement() {
1162 if (_hot_card_cache->use_cache()) {
1163 _hot_card_cache->reset_card_counts();
1164 _hot_card_cache->reset_hot_cache();
1165 }
1166
1167 // Discard all remembered set updates.
1168 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1169 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1170 }
1171
1172 void G1CollectedHeap::verify_after_full_collection() {
1173 check_gc_time_stamps();
1174 _hrm.verify_optional();
1175 _verifier->verify_region_sets_optional();
1176 _verifier->verify_after_gc();
1177 // Clear the previous marking bitmap, if needed for bitmap verification.
1178 // Note we cannot do this when we clear the next marking bitmap in
1179 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1180 // objects marked during a full GC against the previous bitmap.
1181 // But we need to clear it before calling check_bitmaps below since
1182 // the full GC has compacted objects and updated TAMS but not updated
1183 // the prev bitmap.
1184 if (G1VerifyBitmaps) {
1185 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1186 _cm->clear_prev_bitmap(workers());
1187 }
1188 _verifier->check_bitmaps("Full GC End");
1189
1190 // At this point there should be no regions in the
1191 // entire heap tagged as young.
1192 assert(check_young_list_empty(), "young list should be empty at this point");
1193
1194 // Note: since we've just done a full GC, concurrent
1195 // marking is no longer active. Therefore we need not
1196 // re-enable reference discovery for the CM ref processor.
1197 // That will be done at the start of the next marking cycle.
1198 // We also know that the STW processor should no longer
1199 // discover any new references.
1200 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1201 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1202 ref_processor_stw()->verify_no_references_recorded();
1203 ref_processor_cm()->verify_no_references_recorded();
1204 }
1205
1206 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1207 print_hrm_post_compaction();
1208 heap_transition->print();
1209 print_heap_after_gc();
1210 print_heap_regions();
1211 #ifdef TRACESPINNING
1212 ParallelTaskTerminator::print_termination_counts();
1213 #endif
1214 }
1215
1216 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1217 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1218 g1_policy()->record_full_collection_start();
1219
1220 print_heap_before_gc();
1221 print_heap_regions();
1222
1223 abort_concurrent_cycle();
1224 verify_before_full_collection(scope->is_explicit_gc());
1225
1226 gc_prologue(true);
1227 prepare_heap_for_full_collection();
1228
1229 G1SerialFullCollector serial(scope, ref_processor_stw());
1230 serial.prepare_collection();
1231 serial.collect();
1232 serial.complete_collection();
1233
1234 prepare_heap_for_mutators();
1235
1236 g1_policy()->record_full_collection_end();
1237 gc_epilogue(true);
1238
1239 // Post collection verification.
1240 verify_after_full_collection();
1241
1242 // Post collection logging.
1243 // We should do this after we potentially resize the heap so
1244 // that all the COMMIT / UNCOMMIT events are generated before
1245 // the compaction events.
1246 print_heap_after_full_collection(scope->heap_transition());
1247 }
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 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1552 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1553 _g1_policy(create_g1_policy(_gc_timer_stw)),
1554 _collection_set(this, _g1_policy),
1555 _dirty_card_queue_set(false),
1556 _is_alive_closure_cm(this),
1557 _is_alive_closure_stw(this),
1558 _ref_processor_cm(NULL),
1559 _ref_processor_stw(NULL),
1560 _bot(NULL),
1561 _hot_card_cache(NULL),
1562 _g1_rem_set(NULL),
1563 _cg1r(NULL),
1564 _g1mm(NULL),
1565 _preserved_marks_set(true /* in_c_heap */),
1566 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1567 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1568 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1569 _humongous_reclaim_candidates(),
1570 _has_humongous_reclaim_candidates(false),
1571 _archive_allocator(NULL),
1572 _free_regions_coming(false),
1573 _gc_time_stamp(0),
1574 _summary_bytes_used(0),
1575 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1576 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1577 _expand_heap_after_alloc_failure(true),
1578 _old_marking_cycles_started(0),
1579 _old_marking_cycles_completed(0),
1580 _in_cset_fast_test() {
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(&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 G1CardTable* ct = new G1CardTable(reserved_region());
1690 ct->initialize();
1691 G1BarrierSet* bs = new G1BarrierSet(ct);
1692 bs->initialize();
1693 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1694 set_barrier_set(bs);
1695
1696 // Create the hot card cache.
1697 _hot_card_cache = new G1HotCardCache(this);
1698
1699 // Carve out the G1 part of the heap.
1700 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1701 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1702 G1RegionToSpaceMapper* heap_storage =
1703 G1RegionToSpaceMapper::create_mapper(g1_rs,
1704 g1_rs.size(),
1705 page_size,
1706 HeapRegion::GrainBytes,
1707 1,
1708 mtJavaHeap);
1709 os::trace_page_sizes("Heap",
1710 collector_policy()->min_heap_byte_size(),
1711 max_byte_size,
1712 page_size,
1713 heap_rs.base(),
1714 heap_rs.size());
1715 heap_storage->set_mapping_changed_listener(&_listener);
1716
1717 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1718 G1RegionToSpaceMapper* bot_storage =
1719 create_aux_memory_mapper("Block Offset Table",
1720 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1721 G1BlockOffsetTable::heap_map_factor());
1722
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_card_table()->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_card_table(), _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 G1BarrierSet::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 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1800 DirtyCardQ_FL_lock,
1801 (int)concurrent_g1_refine()->yellow_zone(),
1802 (int)concurrent_g1_refine()->red_zone(),
1803 Shared_DirtyCardQ_lock,
1804 NULL, // fl_owner
1805 true); // init_free_ids
1806
1807 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1808 DirtyCardQ_FL_lock,
1809 -1, // never trigger processing
1810 -1, // no limit on length
1811 Shared_DirtyCardQ_lock,
1812 &G1BarrierSet::dirty_card_queue_set());
1813
1814 // Here we allocate the dummy HeapRegion that is required by the
1815 // G1AllocRegion class.
1816 HeapRegion* dummy_region = _hrm.get_dummy_region();
1817
1818 // We'll re-use the same region whether the alloc region will
1819 // require BOT updates or not and, if it doesn't, then a non-young
1820 // region will complain that it cannot support allocations without
1821 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1822 dummy_region->set_eden();
1823 // Make sure it's full.
1824 dummy_region->set_top(dummy_region->end());
1825 G1AllocRegion::setup(this, dummy_region);
1826
1827 _allocator->init_mutator_alloc_region();
1828
1829 // Do create of the monitoring and management support so that
1830 // values in the heap have been properly initialized.
1831 _g1mm = new G1MonitoringSupport(this);
1832
1833 G1StringDedup::initialize();
1834
1835 _preserved_marks_set.init(ParallelGCThreads);
1836
1837 _collection_set.initialize(max_regions());
1838
1839 return JNI_OK;
1840 }
1841
1842 void G1CollectedHeap::stop() {
1843 // Stop all concurrent threads. We do this to make sure these threads
1844 // do not continue to execute and access resources (e.g. logging)
1845 // that are destroyed during shutdown.
1846 _cg1r->stop();
1847 _cmThread->stop();
1848 if (G1StringDedup::is_enabled()) {
1849 G1StringDedup::stop();
1850 }
1851 }
1852
1853 void G1CollectedHeap::safepoint_synchronize_begin() {
1854 SuspendibleThreadSet::synchronize();
1855 }
1856
1857 void G1CollectedHeap::safepoint_synchronize_end() {
1858 SuspendibleThreadSet::desynchronize();
1859 }
1860
1861 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1862 return HeapRegion::max_region_size();
1863 }
1864
1865 void G1CollectedHeap::post_initialize() {
1866 ref_processing_init();
1867 }
1868
1869 void G1CollectedHeap::ref_processing_init() {
1870 // Reference processing in G1 currently works as follows:
1871 //
1872 // * There are two reference processor instances. One is
1873 // used to record and process discovered references
1874 // during concurrent marking; the other is used to
1875 // record and process references during STW pauses
1876 // (both full and incremental).
1877 // * Both ref processors need to 'span' the entire heap as
1878 // the regions in the collection set may be dotted around.
1879 //
1880 // * For the concurrent marking ref processor:
1881 // * Reference discovery is enabled at initial marking.
1882 // * Reference discovery is disabled and the discovered
1883 // references processed etc during remarking.
1884 // * Reference discovery is MT (see below).
1885 // * Reference discovery requires a barrier (see below).
1886 // * Reference processing may or may not be MT
1887 // (depending on the value of ParallelRefProcEnabled
1888 // and ParallelGCThreads).
1889 // * A full GC disables reference discovery by the CM
1890 // ref processor and abandons any entries on it's
1891 // discovered lists.
1892 //
1893 // * For the STW processor:
1894 // * Non MT discovery is enabled at the start of a full GC.
1895 // * Processing and enqueueing during a full GC is non-MT.
1896 // * During a full GC, references are processed after marking.
1897 //
1898 // * Discovery (may or may not be MT) is enabled at the start
1899 // of an incremental evacuation pause.
1900 // * References are processed near the end of a STW evacuation pause.
1901 // * For both types of GC:
1902 // * Discovery is atomic - i.e. not concurrent.
1903 // * Reference discovery will not need a barrier.
1904
1905 MemRegion mr = reserved_region();
1906
1907 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1908
1909 // Concurrent Mark ref processor
1910 _ref_processor_cm =
1911 new ReferenceProcessor(mr, // span
1912 mt_processing,
1913 // mt processing
1914 ParallelGCThreads,
1915 // degree of mt processing
1916 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1917 // mt discovery
1918 MAX2(ParallelGCThreads, ConcGCThreads),
1919 // degree of mt discovery
1920 false,
1921 // Reference discovery is not atomic
1922 &_is_alive_closure_cm);
1923 // is alive closure
1924 // (for efficiency/performance)
1925
1926 // STW ref processor
1927 _ref_processor_stw =
1928 new ReferenceProcessor(mr, // span
1929 mt_processing,
1930 // mt processing
1931 ParallelGCThreads,
1932 // degree of mt processing
1933 (ParallelGCThreads > 1),
1934 // mt discovery
1935 ParallelGCThreads,
1936 // degree of mt discovery
1937 true,
1938 // Reference discovery is atomic
1939 &_is_alive_closure_stw);
1940 // is alive closure
1941 // (for efficiency/performance)
1942 }
1943
1944 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1945 return _collector_policy;
1946 }
1947
1948 size_t G1CollectedHeap::capacity() const {
1949 return _hrm.length() * HeapRegion::GrainBytes;
1950 }
1951
1952 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1953 hr->reset_gc_time_stamp();
1954 }
1955
1956 #ifndef PRODUCT
1957
1958 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1959 private:
1960 unsigned _gc_time_stamp;
1961 bool _failures;
1962
1963 public:
1964 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1965 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1966
1967 virtual bool doHeapRegion(HeapRegion* hr) {
1968 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1969 if (_gc_time_stamp != region_gc_time_stamp) {
1970 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1971 region_gc_time_stamp, _gc_time_stamp);
1972 _failures = true;
1973 }
1974 return false;
1975 }
1976
1977 bool failures() { return _failures; }
1978 };
1979
1980 void G1CollectedHeap::check_gc_time_stamps() {
1981 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1982 heap_region_iterate(&cl);
1983 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1984 }
1985 #endif // PRODUCT
1986
1987 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1988 _hot_card_cache->drain(cl, worker_i);
1989 }
1990
1991 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1992 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1993 size_t n_completed_buffers = 0;
1994 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1995 n_completed_buffers++;
1996 }
1997 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1998 dcqs.clear_n_completed_buffers();
1999 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2000 }
2001
2002 // Computes the sum of the storage used by the various regions.
2003 size_t G1CollectedHeap::used() const {
2004 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2005 if (_archive_allocator != NULL) {
2006 result += _archive_allocator->used();
2007 }
2008 return result;
2009 }
2010
2011 size_t G1CollectedHeap::used_unlocked() const {
2012 return _summary_bytes_used;
2013 }
2014
2015 class SumUsedClosure: public HeapRegionClosure {
2016 size_t _used;
2017 public:
2018 SumUsedClosure() : _used(0) {}
2019 bool doHeapRegion(HeapRegion* r) {
2020 _used += r->used();
2021 return false;
2022 }
2023 size_t result() { return _used; }
2024 };
2025
2026 size_t G1CollectedHeap::recalculate_used() const {
2027 double recalculate_used_start = os::elapsedTime();
2028
2029 SumUsedClosure blk;
2030 heap_region_iterate(&blk);
2031
2032 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2033 return blk.result();
2034 }
2035
2036 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2037 switch (cause) {
2038 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2039 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2040 case GCCause::_update_allocation_context_stats_inc: return true;
2041 case GCCause::_wb_conc_mark: return true;
2042 default : return false;
2043 }
2044 }
2045
2046 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2047 switch (cause) {
2048 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2049 case GCCause::_g1_humongous_allocation: return true;
2050 default: return is_user_requested_concurrent_full_gc(cause);
2051 }
2052 }
2053
2054 #ifndef PRODUCT
2055 void G1CollectedHeap::allocate_dummy_regions() {
2056 // Let's fill up most of the region
2057 size_t word_size = HeapRegion::GrainWords - 1024;
2058 // And as a result the region we'll allocate will be humongous.
2059 guarantee(is_humongous(word_size), "sanity");
2060
2061 // _filler_array_max_size is set to humongous object threshold
2062 // but temporarily change it to use CollectedHeap::fill_with_object().
2063 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2064
2065 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2066 // Let's use the existing mechanism for the allocation
2067 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2068 AllocationContext::system());
2069 if (dummy_obj != NULL) {
2070 MemRegion mr(dummy_obj, word_size);
2071 CollectedHeap::fill_with_object(mr);
2072 } else {
2073 // If we can't allocate once, we probably cannot allocate
2074 // again. Let's get out of the loop.
2075 break;
2076 }
2077 }
2078 }
2079 #endif // !PRODUCT
2080
2081 void G1CollectedHeap::increment_old_marking_cycles_started() {
2082 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2083 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2084 "Wrong marking cycle count (started: %d, completed: %d)",
2085 _old_marking_cycles_started, _old_marking_cycles_completed);
2086
2087 _old_marking_cycles_started++;
2088 }
2089
2090 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2091 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2092
2093 // We assume that if concurrent == true, then the caller is a
2094 // concurrent thread that was joined the Suspendible Thread
2095 // Set. If there's ever a cheap way to check this, we should add an
2096 // assert here.
2097
2098 // Given that this method is called at the end of a Full GC or of a
2099 // concurrent cycle, and those can be nested (i.e., a Full GC can
2100 // interrupt a concurrent cycle), the number of full collections
2101 // completed should be either one (in the case where there was no
2102 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2103 // behind the number of full collections started.
2104
2105 // This is the case for the inner caller, i.e. a Full GC.
2106 assert(concurrent ||
2107 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2108 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2109 "for inner caller (Full GC): _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 // This is the case for the outer caller, i.e. the concurrent cycle.
2114 assert(!concurrent ||
2115 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2116 "for outer caller (concurrent cycle): "
2117 "_old_marking_cycles_started = %u "
2118 "is inconsistent with _old_marking_cycles_completed = %u",
2119 _old_marking_cycles_started, _old_marking_cycles_completed);
2120
2121 _old_marking_cycles_completed += 1;
2122
2123 // We need to clear the "in_progress" flag in the CM thread before
2124 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2125 // is set) so that if a waiter requests another System.gc() it doesn't
2126 // incorrectly see that a marking cycle is still in progress.
2127 if (concurrent) {
2128 _cmThread->set_idle();
2129 }
2130
2131 // This notify_all() will ensure that a thread that called
2132 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2133 // and it's waiting for a full GC to finish will be woken up. It is
2134 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2135 FullGCCount_lock->notify_all();
2136 }
2137
2138 void G1CollectedHeap::collect(GCCause::Cause cause) {
2139 assert_heap_not_locked();
2140
2141 uint gc_count_before;
2142 uint old_marking_count_before;
2143 uint full_gc_count_before;
2144 bool retry_gc;
2145
2146 do {
2147 retry_gc = false;
2148
2149 {
2150 MutexLocker ml(Heap_lock);
2151
2152 // Read the GC count while holding the Heap_lock
2153 gc_count_before = total_collections();
2154 full_gc_count_before = total_full_collections();
2155 old_marking_count_before = _old_marking_cycles_started;
2156 }
2157
2158 if (should_do_concurrent_full_gc(cause)) {
2159 // Schedule an initial-mark evacuation pause that will start a
2160 // concurrent cycle. We're setting word_size to 0 which means that
2161 // we are not requesting a post-GC allocation.
2162 VM_G1IncCollectionPause op(gc_count_before,
2163 0, /* word_size */
2164 true, /* should_initiate_conc_mark */
2165 g1_policy()->max_pause_time_ms(),
2166 cause);
2167 op.set_allocation_context(AllocationContext::current());
2168
2169 VMThread::execute(&op);
2170 if (!op.pause_succeeded()) {
2171 if (old_marking_count_before == _old_marking_cycles_started) {
2172 retry_gc = op.should_retry_gc();
2173 } else {
2174 // A Full GC happened while we were trying to schedule the
2175 // initial-mark GC. No point in starting a new cycle given
2176 // that the whole heap was collected anyway.
2177 }
2178
2179 if (retry_gc) {
2180 if (GCLocker::is_active_and_needs_gc()) {
2181 GCLocker::stall_until_clear();
2182 }
2183 }
2184 }
2185 } else {
2186 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2187 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2188
2189 // Schedule a standard evacuation pause. We're setting word_size
2190 // to 0 which means that we are not requesting a post-GC allocation.
2191 VM_G1IncCollectionPause op(gc_count_before,
2192 0, /* word_size */
2193 false, /* should_initiate_conc_mark */
2194 g1_policy()->max_pause_time_ms(),
2195 cause);
2196 VMThread::execute(&op);
2197 } else {
2198 // Schedule a Full GC.
2199 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2200 VMThread::execute(&op);
2201 }
2202 }
2203 } while (retry_gc);
2204 }
2205
2206 bool G1CollectedHeap::is_in(const void* p) const {
2207 if (_hrm.reserved().contains(p)) {
2208 // Given that we know that p is in the reserved space,
2209 // heap_region_containing() should successfully
2210 // return the containing region.
2211 HeapRegion* hr = heap_region_containing(p);
2212 return hr->is_in(p);
2213 } else {
2214 return false;
2215 }
2216 }
2217
2218 #ifdef ASSERT
2219 bool G1CollectedHeap::is_in_exact(const void* p) const {
2220 bool contains = reserved_region().contains(p);
2221 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2222 if (contains && available) {
2223 return true;
2224 } else {
2225 return false;
2226 }
2227 }
2228 #endif
2229
2230 // Iteration functions.
2231
2232 // Iterates an ObjectClosure over all objects within a HeapRegion.
2233
2234 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2235 ObjectClosure* _cl;
2236 public:
2237 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2238 bool doHeapRegion(HeapRegion* r) {
2239 if (!r->is_continues_humongous()) {
2240 r->object_iterate(_cl);
2241 }
2242 return false;
2243 }
2244 };
2245
2246 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2247 IterateObjectClosureRegionClosure blk(cl);
2248 heap_region_iterate(&blk);
2249 }
2250
2251 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2252 _hrm.iterate(cl);
2253 }
2254
2255 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2256 uint worker_id,
2257 HeapRegionClaimer *hrclaimer) const {
2258 _hrm.par_iterate(cl, worker_id, hrclaimer);
2259 }
2260
2261 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2262 _collection_set.iterate(cl);
2263 }
2264
2265 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2266 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2267 }
2268
2269 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2270 HeapRegion* result = _hrm.next_region_in_heap(from);
2271 while (result != NULL && result->is_pinned()) {
2272 result = _hrm.next_region_in_heap(result);
2273 }
2274 return result;
2275 }
2276
2277 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2278 HeapRegion* hr = heap_region_containing(addr);
2279 return hr->block_start(addr);
2280 }
2281
2282 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2283 HeapRegion* hr = heap_region_containing(addr);
2284 return hr->block_size(addr);
2285 }
2286
2287 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2288 HeapRegion* hr = heap_region_containing(addr);
2289 return hr->block_is_obj(addr);
2290 }
2291
2292 bool G1CollectedHeap::supports_tlab_allocation() const {
2293 return true;
2294 }
2295
2296 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2297 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2298 }
2299
2300 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2301 return _eden.length() * HeapRegion::GrainBytes;
2302 }
2303
2304 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2305 // must be equal to the humongous object limit.
2306 size_t G1CollectedHeap::max_tlab_size() const {
2307 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2308 }
2309
2310 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2311 AllocationContext_t context = AllocationContext::current();
2312 return _allocator->unsafe_max_tlab_alloc(context);
2313 }
2314
2315 size_t G1CollectedHeap::max_capacity() const {
2316 return _hrm.reserved().byte_size();
2317 }
2318
2319 jlong G1CollectedHeap::millis_since_last_gc() {
2320 // See the notes in GenCollectedHeap::millis_since_last_gc()
2321 // for more information about the implementation.
2322 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2323 _g1_policy->collection_pause_end_millis();
2324 if (ret_val < 0) {
2325 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2326 ". returning zero instead.", ret_val);
2327 return 0;
2328 }
2329 return ret_val;
2330 }
2331
2332 void G1CollectedHeap::prepare_for_verify() {
2333 _verifier->prepare_for_verify();
2334 }
2335
2336 void G1CollectedHeap::verify(VerifyOption vo) {
2337 _verifier->verify(vo);
2338 }
2339
2340 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2341 return true;
2342 }
2343
2344 const char* const* G1CollectedHeap::concurrent_phases() const {
2345 return _cmThread->concurrent_phases();
2346 }
2347
2348 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2349 return _cmThread->request_concurrent_phase(phase);
2350 }
2351
2352 class PrintRegionClosure: public HeapRegionClosure {
2353 outputStream* _st;
2354 public:
2355 PrintRegionClosure(outputStream* st) : _st(st) {}
2356 bool doHeapRegion(HeapRegion* r) {
2357 r->print_on(_st);
2358 return false;
2359 }
2360 };
2361
2362 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2363 const HeapRegion* hr,
2364 const VerifyOption vo) const {
2365 switch (vo) {
2366 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2367 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2368 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2369 default: ShouldNotReachHere();
2370 }
2371 return false; // keep some compilers happy
2372 }
2373
2374 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2375 const VerifyOption vo) const {
2376 switch (vo) {
2377 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2378 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2379 case VerifyOption_G1UseMarkWord: {
2380 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2381 return !obj->is_gc_marked() && !hr->is_archive();
2382 }
2383 default: ShouldNotReachHere();
2384 }
2385 return false; // keep some compilers happy
2386 }
2387
2388 void G1CollectedHeap::print_heap_regions() const {
2389 LogTarget(Trace, gc, heap, region) lt;
2390 if (lt.is_enabled()) {
2391 LogStream ls(lt);
2392 print_regions_on(&ls);
2393 }
2394 }
2395
2396 void G1CollectedHeap::print_on(outputStream* st) const {
2397 st->print(" %-20s", "garbage-first heap");
2398 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2399 capacity()/K, used_unlocked()/K);
2400 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2401 p2i(_hrm.reserved().start()),
2402 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2403 p2i(_hrm.reserved().end()));
2404 st->cr();
2405 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2406 uint young_regions = young_regions_count();
2407 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2408 (size_t) young_regions * HeapRegion::GrainBytes / K);
2409 uint survivor_regions = survivor_regions_count();
2410 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2411 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2412 st->cr();
2413 MetaspaceAux::print_on(st);
2414 }
2415
2416 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2417 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2418 "HS=humongous(starts), HC=humongous(continues), "
2419 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2420 "AC=allocation context, "
2421 "TAMS=top-at-mark-start (previous, next)");
2422 PrintRegionClosure blk(st);
2423 heap_region_iterate(&blk);
2424 }
2425
2426 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2427 print_on(st);
2428
2429 // Print the per-region information.
2430 print_regions_on(st);
2431 }
2432
2433 void G1CollectedHeap::print_on_error(outputStream* st) const {
2434 this->CollectedHeap::print_on_error(st);
2435
2436 if (_cm != NULL) {
2437 st->cr();
2438 _cm->print_on_error(st);
2439 }
2440 }
2441
2442 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2443 workers()->print_worker_threads_on(st);
2444 _cmThread->print_on(st);
2445 st->cr();
2446 _cm->print_worker_threads_on(st);
2447 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2448 if (G1StringDedup::is_enabled()) {
2449 G1StringDedup::print_worker_threads_on(st);
2450 }
2451 }
2452
2453 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2454 workers()->threads_do(tc);
2455 tc->do_thread(_cmThread);
2456 _cm->threads_do(tc);
2457 _cg1r->threads_do(tc); // also iterates over the sample thread
2458 if (G1StringDedup::is_enabled()) {
2459 G1StringDedup::threads_do(tc);
2460 }
2461 }
2462
2463 void G1CollectedHeap::print_tracing_info() const {
2464 g1_rem_set()->print_summary_info();
2465 concurrent_mark()->print_summary_info();
2466 }
2467
2468 #ifndef PRODUCT
2469 // Helpful for debugging RSet issues.
2470
2471 class PrintRSetsClosure : public HeapRegionClosure {
2472 private:
2473 const char* _msg;
2474 size_t _occupied_sum;
2475
2476 public:
2477 bool doHeapRegion(HeapRegion* r) {
2478 HeapRegionRemSet* hrrs = r->rem_set();
2479 size_t occupied = hrrs->occupied();
2480 _occupied_sum += occupied;
2481
2482 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2483 if (occupied == 0) {
2484 tty->print_cr(" RSet is empty");
2485 } else {
2486 hrrs->print();
2487 }
2488 tty->print_cr("----------");
2489 return false;
2490 }
2491
2492 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2493 tty->cr();
2494 tty->print_cr("========================================");
2495 tty->print_cr("%s", msg);
2496 tty->cr();
2497 }
2498
2499 ~PrintRSetsClosure() {
2500 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2501 tty->print_cr("========================================");
2502 tty->cr();
2503 }
2504 };
2505
2506 void G1CollectedHeap::print_cset_rsets() {
2507 PrintRSetsClosure cl("Printing CSet RSets");
2508 collection_set_iterate(&cl);
2509 }
2510
2511 void G1CollectedHeap::print_all_rsets() {
2512 PrintRSetsClosure cl("Printing All RSets");;
2513 heap_region_iterate(&cl);
2514 }
2515 #endif // PRODUCT
2516
2517 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2518
2519 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2520 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2521 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2522
2523 size_t eden_capacity_bytes =
2524 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2525
2526 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2527 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2528 eden_capacity_bytes, survivor_used_bytes, num_regions());
2529 }
2530
2531 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2532 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2533 stats->unused(), stats->used(), stats->region_end_waste(),
2534 stats->regions_filled(), stats->direct_allocated(),
2535 stats->failure_used(), stats->failure_waste());
2536 }
2537
2538 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2539 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2540 gc_tracer->report_gc_heap_summary(when, heap_summary);
2541
2542 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2543 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2544 }
2545
2546 G1CollectedHeap* G1CollectedHeap::heap() {
2547 CollectedHeap* heap = Universe::heap();
2548 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2549 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2550 return (G1CollectedHeap*)heap;
2551 }
2552
2553 void G1CollectedHeap::gc_prologue(bool full) {
2554 // always_do_update_barrier = false;
2555 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2556
2557 // This summary needs to be printed before incrementing total collections.
2558 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2559
2560 // Update common counters.
2561 increment_total_collections(full /* full gc */);
2562 if (full) {
2563 increment_old_marking_cycles_started();
2564 reset_gc_time_stamp();
2565 } else {
2566 increment_gc_time_stamp();
2567 }
2568
2569 // Fill TLAB's and such
2570 double start = os::elapsedTime();
2571 accumulate_statistics_all_tlabs();
2572 ensure_parsability(true);
2573 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2574 }
2575
2576 void G1CollectedHeap::gc_epilogue(bool full) {
2577 // Update common counters.
2578 if (full) {
2579 // Update the number of full collections that have been completed.
2580 increment_old_marking_cycles_completed(false /* concurrent */);
2581 }
2582
2583 // We are at the end of the GC. Total collections has already been increased.
2584 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2585
2586 // FIXME: what is this about?
2587 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2588 // is set.
2589 #if defined(COMPILER2) || INCLUDE_JVMCI
2590 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2591 #endif
2592 // always_do_update_barrier = true;
2593
2594 double start = os::elapsedTime();
2595 resize_all_tlabs();
2596 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2597
2598 allocation_context_stats().update(full);
2599
2600 MemoryService::track_memory_usage();
2601 // We have just completed a GC. Update the soft reference
2602 // policy with the new heap occupancy
2603 Universe::update_heap_info_at_gc();
2604 }
2605
2606 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2607 uint gc_count_before,
2608 bool* succeeded,
2609 GCCause::Cause gc_cause) {
2610 assert_heap_not_locked_and_not_at_safepoint();
2611 VM_G1IncCollectionPause op(gc_count_before,
2612 word_size,
2613 false, /* should_initiate_conc_mark */
2614 g1_policy()->max_pause_time_ms(),
2615 gc_cause);
2616
2617 op.set_allocation_context(AllocationContext::current());
2618 VMThread::execute(&op);
2619
2620 HeapWord* result = op.result();
2621 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2622 assert(result == NULL || ret_succeeded,
2623 "the result should be NULL if the VM did not succeed");
2624 *succeeded = ret_succeeded;
2625
2626 assert_heap_not_locked();
2627 return result;
2628 }
2629
2630 void
2631 G1CollectedHeap::doConcurrentMark() {
2632 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2633 if (!_cmThread->in_progress()) {
2634 _cmThread->set_started();
2635 CGC_lock->notify();
2636 }
2637 }
2638
2639 size_t G1CollectedHeap::pending_card_num() {
2640 size_t extra_cards = 0;
2641 JavaThread *curr = Threads::first();
2642 while (curr != NULL) {
2643 DirtyCardQueue& dcq = curr->dirty_card_queue();
2644 extra_cards += dcq.size();
2645 curr = curr->next();
2646 }
2647 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2648 size_t buffer_size = dcqs.buffer_size();
2649 size_t buffer_num = dcqs.completed_buffers_num();
2650
2651 return buffer_size * buffer_num + extra_cards;
2652 }
2653
2654 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2655 private:
2656 size_t _total_humongous;
2657 size_t _candidate_humongous;
2658
2659 DirtyCardQueue _dcq;
2660
2661 // We don't nominate objects with many remembered set entries, on
2662 // the assumption that such objects are likely still live.
2663 bool is_remset_small(HeapRegion* region) const {
2664 HeapRegionRemSet* const rset = region->rem_set();
2665 return G1EagerReclaimHumongousObjectsWithStaleRefs
2666 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2667 : rset->is_empty();
2668 }
2669
2670 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2671 assert(region->is_starts_humongous(), "Must start a humongous object");
2672
2673 oop obj = oop(region->bottom());
2674
2675 // Dead objects cannot be eager reclaim candidates. Due to class
2676 // unloading it is unsafe to query their classes so we return early.
2677 if (heap->is_obj_dead(obj, region)) {
2678 return false;
2679 }
2680
2681 // Candidate selection must satisfy the following constraints
2682 // while concurrent marking is in progress:
2683 //
2684 // * In order to maintain SATB invariants, an object must not be
2685 // reclaimed if it was allocated before the start of marking and
2686 // has not had its references scanned. Such an object must have
2687 // its references (including type metadata) scanned to ensure no
2688 // live objects are missed by the marking process. Objects
2689 // allocated after the start of concurrent marking don't need to
2690 // be scanned.
2691 //
2692 // * An object must not be reclaimed if it is on the concurrent
2693 // mark stack. Objects allocated after the start of concurrent
2694 // marking are never pushed on the mark stack.
2695 //
2696 // Nominating only objects allocated after the start of concurrent
2697 // marking is sufficient to meet both constraints. This may miss
2698 // some objects that satisfy the constraints, but the marking data
2699 // structures don't support efficiently performing the needed
2700 // additional tests or scrubbing of the mark stack.
2701 //
2702 // However, we presently only nominate is_typeArray() objects.
2703 // A humongous object containing references induces remembered
2704 // set entries on other regions. In order to reclaim such an
2705 // object, those remembered sets would need to be cleaned up.
2706 //
2707 // We also treat is_typeArray() objects specially, allowing them
2708 // to be reclaimed even if allocated before the start of
2709 // concurrent mark. For this we rely on mark stack insertion to
2710 // exclude is_typeArray() objects, preventing reclaiming an object
2711 // that is in the mark stack. We also rely on the metadata for
2712 // such objects to be built-in and so ensured to be kept live.
2713 // Frequent allocation and drop of large binary blobs is an
2714 // important use case for eager reclaim, and this special handling
2715 // may reduce needed headroom.
2716
2717 return obj->is_typeArray() && is_remset_small(region);
2718 }
2719
2720 public:
2721 RegisterHumongousWithInCSetFastTestClosure()
2722 : _total_humongous(0),
2723 _candidate_humongous(0),
2724 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2725 }
2726
2727 virtual bool doHeapRegion(HeapRegion* r) {
2728 if (!r->is_starts_humongous()) {
2729 return false;
2730 }
2731 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2732
2733 bool is_candidate = humongous_region_is_candidate(g1h, r);
2734 uint rindex = r->hrm_index();
2735 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2736 if (is_candidate) {
2737 _candidate_humongous++;
2738 g1h->register_humongous_region_with_cset(rindex);
2739 // Is_candidate already filters out humongous object with large remembered sets.
2740 // If we have a humongous object with a few remembered sets, we simply flush these
2741 // remembered set entries into the DCQS. That will result in automatic
2742 // re-evaluation of their remembered set entries during the following evacuation
2743 // phase.
2744 if (!r->rem_set()->is_empty()) {
2745 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2746 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2747 G1CardTable* ct = g1h->g1_card_table();
2748 HeapRegionRemSetIterator hrrs(r->rem_set());
2749 size_t card_index;
2750 while (hrrs.has_next(card_index)) {
2751 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2752 // The remembered set might contain references to already freed
2753 // regions. Filter out such entries to avoid failing card table
2754 // verification.
2755 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2756 if (*card_ptr != G1CardTable::dirty_card_val()) {
2757 *card_ptr = G1CardTable::dirty_card_val();
2758 _dcq.enqueue(card_ptr);
2759 }
2760 }
2761 }
2762 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2763 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2764 hrrs.n_yielded(), r->rem_set()->occupied());
2765 r->rem_set()->clear_locked();
2766 }
2767 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2768 }
2769 _total_humongous++;
2770
2771 return false;
2772 }
2773
2774 size_t total_humongous() const { return _total_humongous; }
2775 size_t candidate_humongous() const { return _candidate_humongous; }
2776
2777 void flush_rem_set_entries() { _dcq.flush(); }
2778 };
2779
2780 void G1CollectedHeap::register_humongous_regions_with_cset() {
2781 if (!G1EagerReclaimHumongousObjects) {
2782 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2783 return;
2784 }
2785 double time = os::elapsed_counter();
2786
2787 // Collect reclaim candidate information and register candidates with cset.
2788 RegisterHumongousWithInCSetFastTestClosure cl;
2789 heap_region_iterate(&cl);
2790
2791 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2792 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2793 cl.total_humongous(),
2794 cl.candidate_humongous());
2795 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2796
2797 // Finally flush all remembered set entries to re-check into the global DCQS.
2798 cl.flush_rem_set_entries();
2799 }
2800
2801 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2802 public:
2803 bool doHeapRegion(HeapRegion* hr) {
2804 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2805 hr->verify_rem_set();
2806 }
2807 return false;
2808 }
2809 };
2810
2811 uint G1CollectedHeap::num_task_queues() const {
2812 return _task_queues->size();
2813 }
2814
2815 #if TASKQUEUE_STATS
2816 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2817 st->print_raw_cr("GC Task Stats");
2818 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2819 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2820 }
2821
2822 void G1CollectedHeap::print_taskqueue_stats() const {
2823 if (!log_is_enabled(Trace, gc, task, stats)) {
2824 return;
2825 }
2826 Log(gc, task, stats) log;
2827 ResourceMark rm;
2828 LogStream ls(log.trace());
2829 outputStream* st = &ls;
2830
2831 print_taskqueue_stats_hdr(st);
2832
2833 TaskQueueStats totals;
2834 const uint n = num_task_queues();
2835 for (uint i = 0; i < n; ++i) {
2836 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2837 totals += task_queue(i)->stats;
2838 }
2839 st->print_raw("tot "); totals.print(st); st->cr();
2840
2841 DEBUG_ONLY(totals.verify());
2842 }
2843
2844 void G1CollectedHeap::reset_taskqueue_stats() {
2845 const uint n = num_task_queues();
2846 for (uint i = 0; i < n; ++i) {
2847 task_queue(i)->stats.reset();
2848 }
2849 }
2850 #endif // TASKQUEUE_STATS
2851
2852 void G1CollectedHeap::wait_for_root_region_scanning() {
2853 double scan_wait_start = os::elapsedTime();
2854 // We have to wait until the CM threads finish scanning the
2855 // root regions as it's the only way to ensure that all the
2856 // objects on them have been correctly scanned before we start
2857 // moving them during the GC.
2858 bool waited = _cm->root_regions()->wait_until_scan_finished();
2859 double wait_time_ms = 0.0;
2860 if (waited) {
2861 double scan_wait_end = os::elapsedTime();
2862 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2863 }
2864 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2865 }
2866
2867 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2868 private:
2869 G1HRPrinter* _hr_printer;
2870 public:
2871 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2872
2873 virtual bool doHeapRegion(HeapRegion* r) {
2874 _hr_printer->cset(r);
2875 return false;
2876 }
2877 };
2878
2879 void G1CollectedHeap::start_new_collection_set() {
2880 collection_set()->start_incremental_building();
2881
2882 clear_cset_fast_test();
2883
2884 guarantee(_eden.length() == 0, "eden should have been cleared");
2885 g1_policy()->transfer_survivors_to_cset(survivor());
2886 }
2887
2888 bool
2889 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2890 assert_at_safepoint(true /* should_be_vm_thread */);
2891 guarantee(!is_gc_active(), "collection is not reentrant");
2892
2893 if (GCLocker::check_active_before_gc()) {
2894 return false;
2895 }
2896
2897 _gc_timer_stw->register_gc_start();
2898
2899 GCIdMark gc_id_mark;
2900 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2901
2902 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2903 ResourceMark rm;
2904
2905 g1_policy()->note_gc_start();
2906
2907 wait_for_root_region_scanning();
2908
2909 print_heap_before_gc();
2910 print_heap_regions();
2911 trace_heap_before_gc(_gc_tracer_stw);
2912
2913 _verifier->verify_region_sets_optional();
2914 _verifier->verify_dirty_young_regions();
2915
2916 // We should not be doing initial mark unless the conc mark thread is running
2917 if (!_cmThread->should_terminate()) {
2918 // This call will decide whether this pause is an initial-mark
2919 // pause. If it is, during_initial_mark_pause() will return true
2920 // for the duration of this pause.
2921 g1_policy()->decide_on_conc_mark_initiation();
2922 }
2923
2924 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2925 assert(!collector_state()->during_initial_mark_pause() ||
2926 collector_state()->gcs_are_young(), "sanity");
2927
2928 // We also do not allow mixed GCs during marking.
2929 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2930
2931 // Record whether this pause is an initial mark. When the current
2932 // thread has completed its logging output and it's safe to signal
2933 // the CM thread, the flag's value in the policy has been reset.
2934 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2935
2936 // Inner scope for scope based logging, timers, and stats collection
2937 {
2938 EvacuationInfo evacuation_info;
2939
2940 if (collector_state()->during_initial_mark_pause()) {
2941 // We are about to start a marking cycle, so we increment the
2942 // full collection counter.
2943 increment_old_marking_cycles_started();
2944 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2945 }
2946
2947 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2948
2949 GCTraceCPUTime tcpu;
2950
2951 FormatBuffer<> gc_string("Pause ");
2952 if (collector_state()->during_initial_mark_pause()) {
2953 gc_string.append("Initial Mark");
2954 } else if (collector_state()->gcs_are_young()) {
2955 gc_string.append("Young");
2956 } else {
2957 gc_string.append("Mixed");
2958 }
2959 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2960
2961 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2962 workers()->active_workers(),
2963 Threads::number_of_non_daemon_threads());
2964 workers()->update_active_workers(active_workers);
2965 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2966
2967 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2968 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2969
2970 // If the secondary_free_list is not empty, append it to the
2971 // free_list. No need to wait for the cleanup operation to finish;
2972 // the region allocation code will check the secondary_free_list
2973 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2974 // set, skip this step so that the region allocation code has to
2975 // get entries from the secondary_free_list.
2976 if (!G1StressConcRegionFreeing) {
2977 append_secondary_free_list_if_not_empty_with_lock();
2978 }
2979
2980 G1HeapTransition heap_transition(this);
2981 size_t heap_used_bytes_before_gc = used();
2982
2983 // Don't dynamically change the number of GC threads this early. A value of
2984 // 0 is used to indicate serial work. When parallel work is done,
2985 // it will be set.
2986
2987 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2988 IsGCActiveMark x;
2989
2990 gc_prologue(false);
2991
2992 if (VerifyRememberedSets) {
2993 log_info(gc, verify)("[Verifying RemSets before GC]");
2994 VerifyRegionRemSetClosure v_cl;
2995 heap_region_iterate(&v_cl);
2996 }
2997
2998 _verifier->verify_before_gc();
2999
3000 _verifier->check_bitmaps("GC Start");
3001
3002 #if defined(COMPILER2) || INCLUDE_JVMCI
3003 DerivedPointerTable::clear();
3004 #endif
3005
3006 // Please see comment in g1CollectedHeap.hpp and
3007 // G1CollectedHeap::ref_processing_init() to see how
3008 // reference processing currently works in G1.
3009
3010 // Enable discovery in the STW reference processor
3011 if (g1_policy()->should_process_references()) {
3012 ref_processor_stw()->enable_discovery();
3013 } else {
3014 ref_processor_stw()->disable_discovery();
3015 }
3016
3017 {
3018 // We want to temporarily turn off discovery by the
3019 // CM ref processor, if necessary, and turn it back on
3020 // on again later if we do. Using a scoped
3021 // NoRefDiscovery object will do this.
3022 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3023
3024 // Forget the current alloc region (we might even choose it to be part
3025 // of the collection set!).
3026 _allocator->release_mutator_alloc_region();
3027
3028 // This timing is only used by the ergonomics to handle our pause target.
3029 // It is unclear why this should not include the full pause. We will
3030 // investigate this in CR 7178365.
3031 //
3032 // Preserving the old comment here if that helps the investigation:
3033 //
3034 // The elapsed time induced by the start time below deliberately elides
3035 // the possible verification above.
3036 double sample_start_time_sec = os::elapsedTime();
3037
3038 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3039
3040 if (collector_state()->during_initial_mark_pause()) {
3041 concurrent_mark()->checkpointRootsInitialPre();
3042 }
3043
3044 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3045
3046 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3047
3048 // Make sure the remembered sets are up to date. This needs to be
3049 // done before register_humongous_regions_with_cset(), because the
3050 // remembered sets are used there to choose eager reclaim candidates.
3051 // If the remembered sets are not up to date we might miss some
3052 // entries that need to be handled.
3053 g1_rem_set()->cleanupHRRS();
3054
3055 register_humongous_regions_with_cset();
3056
3057 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3058
3059 // We call this after finalize_cset() to
3060 // ensure that the CSet has been finalized.
3061 _cm->verify_no_cset_oops();
3062
3063 if (_hr_printer.is_active()) {
3064 G1PrintCollectionSetClosure cl(&_hr_printer);
3065 _collection_set.iterate(&cl);
3066 }
3067
3068 // Initialize the GC alloc regions.
3069 _allocator->init_gc_alloc_regions(evacuation_info);
3070
3071 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3072 pre_evacuate_collection_set();
3073
3074 // Actually do the work...
3075 evacuate_collection_set(evacuation_info, &per_thread_states);
3076
3077 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3078
3079 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3080 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3081
3082 eagerly_reclaim_humongous_regions();
3083
3084 record_obj_copy_mem_stats();
3085 _survivor_evac_stats.adjust_desired_plab_sz();
3086 _old_evac_stats.adjust_desired_plab_sz();
3087
3088 double start = os::elapsedTime();
3089 start_new_collection_set();
3090 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3091
3092 if (evacuation_failed()) {
3093 set_used(recalculate_used());
3094 if (_archive_allocator != NULL) {
3095 _archive_allocator->clear_used();
3096 }
3097 for (uint i = 0; i < ParallelGCThreads; i++) {
3098 if (_evacuation_failed_info_array[i].has_failed()) {
3099 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3100 }
3101 }
3102 } else {
3103 // The "used" of the the collection set have already been subtracted
3104 // when they were freed. Add in the bytes evacuated.
3105 increase_used(g1_policy()->bytes_copied_during_gc());
3106 }
3107
3108 if (collector_state()->during_initial_mark_pause()) {
3109 // We have to do this before we notify the CM threads that
3110 // they can start working to make sure that all the
3111 // appropriate initialization is done on the CM object.
3112 concurrent_mark()->checkpointRootsInitialPost();
3113 collector_state()->set_mark_in_progress(true);
3114 // Note that we don't actually trigger the CM thread at
3115 // this point. We do that later when we're sure that
3116 // the current thread has completed its logging output.
3117 }
3118
3119 allocate_dummy_regions();
3120
3121 _allocator->init_mutator_alloc_region();
3122
3123 {
3124 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3125 if (expand_bytes > 0) {
3126 size_t bytes_before = capacity();
3127 // No need for an ergo logging here,
3128 // expansion_amount() does this when it returns a value > 0.
3129 double expand_ms;
3130 if (!expand(expand_bytes, _workers, &expand_ms)) {
3131 // We failed to expand the heap. Cannot do anything about it.
3132 }
3133 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3134 }
3135 }
3136
3137 // We redo the verification but now wrt to the new CSet which
3138 // has just got initialized after the previous CSet was freed.
3139 _cm->verify_no_cset_oops();
3140
3141 // This timing is only used by the ergonomics to handle our pause target.
3142 // It is unclear why this should not include the full pause. We will
3143 // investigate this in CR 7178365.
3144 double sample_end_time_sec = os::elapsedTime();
3145 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3146 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3147 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3148
3149 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3150 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3151
3152 if (VerifyRememberedSets) {
3153 log_info(gc, verify)("[Verifying RemSets after GC]");
3154 VerifyRegionRemSetClosure v_cl;
3155 heap_region_iterate(&v_cl);
3156 }
3157
3158 _verifier->verify_after_gc();
3159 _verifier->check_bitmaps("GC End");
3160
3161 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3162 ref_processor_stw()->verify_no_references_recorded();
3163
3164 // CM reference discovery will be re-enabled if necessary.
3165 }
3166
3167 #ifdef TRACESPINNING
3168 ParallelTaskTerminator::print_termination_counts();
3169 #endif
3170
3171 gc_epilogue(false);
3172 }
3173
3174 // Print the remainder of the GC log output.
3175 if (evacuation_failed()) {
3176 log_info(gc)("To-space exhausted");
3177 }
3178
3179 g1_policy()->print_phases();
3180 heap_transition.print();
3181
3182 // It is not yet to safe to tell the concurrent mark to
3183 // start as we have some optional output below. We don't want the
3184 // output from the concurrent mark thread interfering with this
3185 // logging output either.
3186
3187 _hrm.verify_optional();
3188 _verifier->verify_region_sets_optional();
3189
3190 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3191 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3192
3193 print_heap_after_gc();
3194 print_heap_regions();
3195 trace_heap_after_gc(_gc_tracer_stw);
3196
3197 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3198 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3199 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3200 // before any GC notifications are raised.
3201 g1mm()->update_sizes();
3202
3203 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3204 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3205 _gc_timer_stw->register_gc_end();
3206 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3207 }
3208 // It should now be safe to tell the concurrent mark thread to start
3209 // without its logging output interfering with the logging output
3210 // that came from the pause.
3211
3212 if (should_start_conc_mark) {
3213 // CAUTION: after the doConcurrentMark() call below,
3214 // the concurrent marking thread(s) could be running
3215 // concurrently with us. Make sure that anything after
3216 // this point does not assume that we are the only GC thread
3217 // running. Note: of course, the actual marking work will
3218 // not start until the safepoint itself is released in
3219 // SuspendibleThreadSet::desynchronize().
3220 doConcurrentMark();
3221 }
3222
3223 return true;
3224 }
3225
3226 void G1CollectedHeap::remove_self_forwarding_pointers() {
3227 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3228 workers()->run_task(&rsfp_task);
3229 }
3230
3231 void G1CollectedHeap::restore_after_evac_failure() {
3232 double remove_self_forwards_start = os::elapsedTime();
3233
3234 remove_self_forwarding_pointers();
3235 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3236 _preserved_marks_set.restore(&task_executor);
3237
3238 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3239 }
3240
3241 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3242 if (!_evacuation_failed) {
3243 _evacuation_failed = true;
3244 }
3245
3246 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3247 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3248 }
3249
3250 bool G1ParEvacuateFollowersClosure::offer_termination() {
3251 G1ParScanThreadState* const pss = par_scan_state();
3252 start_term_time();
3253 const bool res = terminator()->offer_termination();
3254 end_term_time();
3255 return res;
3256 }
3257
3258 void G1ParEvacuateFollowersClosure::do_void() {
3259 G1ParScanThreadState* const pss = par_scan_state();
3260 pss->trim_queue();
3261 do {
3262 pss->steal_and_trim_queue(queues());
3263 } while (!offer_termination());
3264 }
3265
3266 class G1ParTask : public AbstractGangTask {
3267 protected:
3268 G1CollectedHeap* _g1h;
3269 G1ParScanThreadStateSet* _pss;
3270 RefToScanQueueSet* _queues;
3271 G1RootProcessor* _root_processor;
3272 ParallelTaskTerminator _terminator;
3273 uint _n_workers;
3274
3275 public:
3276 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3277 : AbstractGangTask("G1 collection"),
3278 _g1h(g1h),
3279 _pss(per_thread_states),
3280 _queues(task_queues),
3281 _root_processor(root_processor),
3282 _terminator(n_workers, _queues),
3283 _n_workers(n_workers)
3284 {}
3285
3286 void work(uint worker_id) {
3287 if (worker_id >= _n_workers) return; // no work needed this round
3288
3289 double start_sec = os::elapsedTime();
3290 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3291
3292 {
3293 ResourceMark rm;
3294 HandleMark hm;
3295
3296 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3297
3298 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3299 pss->set_ref_processor(rp);
3300
3301 double start_strong_roots_sec = os::elapsedTime();
3302
3303 _root_processor->evacuate_roots(pss->closures(), worker_id);
3304
3305 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3306 // treating the nmethods visited to act as roots for concurrent marking.
3307 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3308 // objects copied by the current evacuation.
3309 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3310 pss->closures()->weak_codeblobs(),
3311 worker_id);
3312
3313 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3314
3315 double term_sec = 0.0;
3316 size_t evac_term_attempts = 0;
3317 {
3318 double start = os::elapsedTime();
3319 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3320 evac.do_void();
3321
3322 evac_term_attempts = evac.term_attempts();
3323 term_sec = evac.term_time();
3324 double elapsed_sec = os::elapsedTime() - start;
3325 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3326 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3327 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3328 }
3329
3330 assert(pss->queue_is_empty(), "should be empty");
3331
3332 if (log_is_enabled(Debug, gc, task, stats)) {
3333 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3334 size_t lab_waste;
3335 size_t lab_undo_waste;
3336 pss->waste(lab_waste, lab_undo_waste);
3337 _g1h->print_termination_stats(worker_id,
3338 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3339 strong_roots_sec * 1000.0, /* strong roots time */
3340 term_sec * 1000.0, /* evac term time */
3341 evac_term_attempts, /* evac term attempts */
3342 lab_waste, /* alloc buffer waste */
3343 lab_undo_waste /* undo waste */
3344 );
3345 }
3346
3347 // Close the inner scope so that the ResourceMark and HandleMark
3348 // destructors are executed here and are included as part of the
3349 // "GC Worker Time".
3350 }
3351 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3352 }
3353 };
3354
3355 void G1CollectedHeap::print_termination_stats_hdr() {
3356 log_debug(gc, task, stats)("GC Termination Stats");
3357 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3358 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3359 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3360 }
3361
3362 void G1CollectedHeap::print_termination_stats(uint worker_id,
3363 double elapsed_ms,
3364 double strong_roots_ms,
3365 double term_ms,
3366 size_t term_attempts,
3367 size_t alloc_buffer_waste,
3368 size_t undo_waste) const {
3369 log_debug(gc, task, stats)
3370 ("%3d %9.2f %9.2f %6.2f "
3371 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3372 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3373 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3374 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3375 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3376 alloc_buffer_waste * HeapWordSize / K,
3377 undo_waste * HeapWordSize / K);
3378 }
3379
3380 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3381 private:
3382 BoolObjectClosure* _is_alive;
3383 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3384
3385 int _initial_string_table_size;
3386 int _initial_symbol_table_size;
3387
3388 bool _process_strings;
3389 int _strings_processed;
3390 int _strings_removed;
3391
3392 bool _process_symbols;
3393 int _symbols_processed;
3394 int _symbols_removed;
3395
3396 bool _process_string_dedup;
3397
3398 public:
3399 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3400 AbstractGangTask("String/Symbol Unlinking"),
3401 _is_alive(is_alive),
3402 _dedup_closure(is_alive, NULL, false),
3403 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3404 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3405 _process_string_dedup(process_string_dedup) {
3406
3407 _initial_string_table_size = StringTable::the_table()->table_size();
3408 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3409 if (process_strings) {
3410 StringTable::clear_parallel_claimed_index();
3411 }
3412 if (process_symbols) {
3413 SymbolTable::clear_parallel_claimed_index();
3414 }
3415 }
3416
3417 ~G1StringAndSymbolCleaningTask() {
3418 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3419 "claim value %d after unlink less than initial string table size %d",
3420 StringTable::parallel_claimed_index(), _initial_string_table_size);
3421 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3422 "claim value %d after unlink less than initial symbol table size %d",
3423 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3424
3425 log_info(gc, stringtable)(
3426 "Cleaned string and symbol table, "
3427 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3428 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3429 strings_processed(), strings_removed(),
3430 symbols_processed(), symbols_removed());
3431 }
3432
3433 void work(uint worker_id) {
3434 int strings_processed = 0;
3435 int strings_removed = 0;
3436 int symbols_processed = 0;
3437 int symbols_removed = 0;
3438 if (_process_strings) {
3439 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3440 Atomic::add(strings_processed, &_strings_processed);
3441 Atomic::add(strings_removed, &_strings_removed);
3442 }
3443 if (_process_symbols) {
3444 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3445 Atomic::add(symbols_processed, &_symbols_processed);
3446 Atomic::add(symbols_removed, &_symbols_removed);
3447 }
3448 if (_process_string_dedup) {
3449 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3450 }
3451 }
3452
3453 size_t strings_processed() const { return (size_t)_strings_processed; }
3454 size_t strings_removed() const { return (size_t)_strings_removed; }
3455
3456 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3457 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3458 };
3459
3460 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3461 private:
3462 static Monitor* _lock;
3463
3464 BoolObjectClosure* const _is_alive;
3465 const bool _unloading_occurred;
3466 const uint _num_workers;
3467
3468 // Variables used to claim nmethods.
3469 CompiledMethod* _first_nmethod;
3470 volatile CompiledMethod* _claimed_nmethod;
3471
3472 // The list of nmethods that need to be processed by the second pass.
3473 volatile CompiledMethod* _postponed_list;
3474 volatile uint _num_entered_barrier;
3475
3476 public:
3477 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3478 _is_alive(is_alive),
3479 _unloading_occurred(unloading_occurred),
3480 _num_workers(num_workers),
3481 _first_nmethod(NULL),
3482 _claimed_nmethod(NULL),
3483 _postponed_list(NULL),
3484 _num_entered_barrier(0)
3485 {
3486 CompiledMethod::increase_unloading_clock();
3487 // Get first alive nmethod
3488 CompiledMethodIterator iter = CompiledMethodIterator();
3489 if(iter.next_alive()) {
3490 _first_nmethod = iter.method();
3491 }
3492 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3493 }
3494
3495 ~G1CodeCacheUnloadingTask() {
3496 CodeCache::verify_clean_inline_caches();
3497
3498 CodeCache::set_needs_cache_clean(false);
3499 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3500
3501 CodeCache::verify_icholder_relocations();
3502 }
3503
3504 private:
3505 void add_to_postponed_list(CompiledMethod* nm) {
3506 CompiledMethod* old;
3507 do {
3508 old = (CompiledMethod*)_postponed_list;
3509 nm->set_unloading_next(old);
3510 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3511 }
3512
3513 void clean_nmethod(CompiledMethod* nm) {
3514 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3515
3516 if (postponed) {
3517 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3518 add_to_postponed_list(nm);
3519 }
3520
3521 // Mark that this thread has been cleaned/unloaded.
3522 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3523 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3524 }
3525
3526 void clean_nmethod_postponed(CompiledMethod* nm) {
3527 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3528 }
3529
3530 static const int MaxClaimNmethods = 16;
3531
3532 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3533 CompiledMethod* first;
3534 CompiledMethodIterator last;
3535
3536 do {
3537 *num_claimed_nmethods = 0;
3538
3539 first = (CompiledMethod*)_claimed_nmethod;
3540 last = CompiledMethodIterator(first);
3541
3542 if (first != NULL) {
3543
3544 for (int i = 0; i < MaxClaimNmethods; i++) {
3545 if (!last.next_alive()) {
3546 break;
3547 }
3548 claimed_nmethods[i] = last.method();
3549 (*num_claimed_nmethods)++;
3550 }
3551 }
3552
3553 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3554 }
3555
3556 CompiledMethod* claim_postponed_nmethod() {
3557 CompiledMethod* claim;
3558 CompiledMethod* next;
3559
3560 do {
3561 claim = (CompiledMethod*)_postponed_list;
3562 if (claim == NULL) {
3563 return NULL;
3564 }
3565
3566 next = claim->unloading_next();
3567
3568 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3569
3570 return claim;
3571 }
3572
3573 public:
3574 // Mark that we're done with the first pass of nmethod cleaning.
3575 void barrier_mark(uint worker_id) {
3576 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3577 _num_entered_barrier++;
3578 if (_num_entered_barrier == _num_workers) {
3579 ml.notify_all();
3580 }
3581 }
3582
3583 // See if we have to wait for the other workers to
3584 // finish their first-pass nmethod cleaning work.
3585 void barrier_wait(uint worker_id) {
3586 if (_num_entered_barrier < _num_workers) {
3587 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3588 while (_num_entered_barrier < _num_workers) {
3589 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3590 }
3591 }
3592 }
3593
3594 // Cleaning and unloading of nmethods. Some work has to be postponed
3595 // to the second pass, when we know which nmethods survive.
3596 void work_first_pass(uint worker_id) {
3597 // The first nmethods is claimed by the first worker.
3598 if (worker_id == 0 && _first_nmethod != NULL) {
3599 clean_nmethod(_first_nmethod);
3600 _first_nmethod = NULL;
3601 }
3602
3603 int num_claimed_nmethods;
3604 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3605
3606 while (true) {
3607 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3608
3609 if (num_claimed_nmethods == 0) {
3610 break;
3611 }
3612
3613 for (int i = 0; i < num_claimed_nmethods; i++) {
3614 clean_nmethod(claimed_nmethods[i]);
3615 }
3616 }
3617 }
3618
3619 void work_second_pass(uint worker_id) {
3620 CompiledMethod* nm;
3621 // Take care of postponed nmethods.
3622 while ((nm = claim_postponed_nmethod()) != NULL) {
3623 clean_nmethod_postponed(nm);
3624 }
3625 }
3626 };
3627
3628 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3629
3630 class G1KlassCleaningTask : public StackObj {
3631 BoolObjectClosure* _is_alive;
3632 volatile jint _clean_klass_tree_claimed;
3633 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3634
3635 public:
3636 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3637 _is_alive(is_alive),
3638 _clean_klass_tree_claimed(0),
3639 _klass_iterator() {
3640 }
3641
3642 private:
3643 bool claim_clean_klass_tree_task() {
3644 if (_clean_klass_tree_claimed) {
3645 return false;
3646 }
3647
3648 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3649 }
3650
3651 InstanceKlass* claim_next_klass() {
3652 Klass* klass;
3653 do {
3654 klass =_klass_iterator.next_klass();
3655 } while (klass != NULL && !klass->is_instance_klass());
3656
3657 // this can be null so don't call InstanceKlass::cast
3658 return static_cast<InstanceKlass*>(klass);
3659 }
3660
3661 public:
3662
3663 void clean_klass(InstanceKlass* ik) {
3664 ik->clean_weak_instanceklass_links(_is_alive);
3665 }
3666
3667 void work() {
3668 ResourceMark rm;
3669
3670 // One worker will clean the subklass/sibling klass tree.
3671 if (claim_clean_klass_tree_task()) {
3672 Klass::clean_subklass_tree(_is_alive);
3673 }
3674
3675 // All workers will help cleaning the classes,
3676 InstanceKlass* klass;
3677 while ((klass = claim_next_klass()) != NULL) {
3678 clean_klass(klass);
3679 }
3680 }
3681 };
3682
3683 class G1ResolvedMethodCleaningTask : public StackObj {
3684 BoolObjectClosure* _is_alive;
3685 volatile jint _resolved_method_task_claimed;
3686 public:
3687 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3688 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3689
3690 bool claim_resolved_method_task() {
3691 if (_resolved_method_task_claimed) {
3692 return false;
3693 }
3694 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3695 }
3696
3697 // These aren't big, one thread can do it all.
3698 void work() {
3699 if (claim_resolved_method_task()) {
3700 ResolvedMethodTable::unlink(_is_alive);
3701 }
3702 }
3703 };
3704
3705
3706 // To minimize the remark pause times, the tasks below are done in parallel.
3707 class G1ParallelCleaningTask : public AbstractGangTask {
3708 private:
3709 G1StringAndSymbolCleaningTask _string_symbol_task;
3710 G1CodeCacheUnloadingTask _code_cache_task;
3711 G1KlassCleaningTask _klass_cleaning_task;
3712 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3713
3714 public:
3715 // The constructor is run in the VMThread.
3716 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3717 AbstractGangTask("Parallel Cleaning"),
3718 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3719 _code_cache_task(num_workers, is_alive, unloading_occurred),
3720 _klass_cleaning_task(is_alive),
3721 _resolved_method_cleaning_task(is_alive) {
3722 }
3723
3724 // The parallel work done by all worker threads.
3725 void work(uint worker_id) {
3726 // Do first pass of code cache cleaning.
3727 _code_cache_task.work_first_pass(worker_id);
3728
3729 // Let the threads mark that the first pass is done.
3730 _code_cache_task.barrier_mark(worker_id);
3731
3732 // Clean the Strings and Symbols.
3733 _string_symbol_task.work(worker_id);
3734
3735 // Clean unreferenced things in the ResolvedMethodTable
3736 _resolved_method_cleaning_task.work();
3737
3738 // Wait for all workers to finish the first code cache cleaning pass.
3739 _code_cache_task.barrier_wait(worker_id);
3740
3741 // Do the second code cache cleaning work, which realize on
3742 // the liveness information gathered during the first pass.
3743 _code_cache_task.work_second_pass(worker_id);
3744
3745 // Clean all klasses that were not unloaded.
3746 _klass_cleaning_task.work();
3747 }
3748 };
3749
3750
3751 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3752 bool class_unloading_occurred) {
3753 uint n_workers = workers()->active_workers();
3754
3755 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3756 workers()->run_task(&g1_unlink_task);
3757 }
3758
3759 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3760 bool process_strings,
3761 bool process_symbols,
3762 bool process_string_dedup) {
3763 if (!process_strings && !process_symbols && !process_string_dedup) {
3764 // Nothing to clean.
3765 return;
3766 }
3767
3768 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3769 workers()->run_task(&g1_unlink_task);
3770
3771 }
3772
3773 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3774 private:
3775 DirtyCardQueueSet* _queue;
3776 G1CollectedHeap* _g1h;
3777 public:
3778 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3779 _queue(queue), _g1h(g1h) { }
3780
3781 virtual void work(uint worker_id) {
3782 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3783 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3784
3785 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3786 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3787
3788 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3789 }
3790 };
3791
3792 void G1CollectedHeap::redirty_logged_cards() {
3793 double redirty_logged_cards_start = os::elapsedTime();
3794
3795 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3796 dirty_card_queue_set().reset_for_par_iteration();
3797 workers()->run_task(&redirty_task);
3798
3799 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3800 dcq.merge_bufferlists(&dirty_card_queue_set());
3801 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3802
3803 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3804 }
3805
3806 // Weak Reference Processing support
3807
3808 // An always "is_alive" closure that is used to preserve referents.
3809 // If the object is non-null then it's alive. Used in the preservation
3810 // of referent objects that are pointed to by reference objects
3811 // discovered by the CM ref processor.
3812 class G1AlwaysAliveClosure: public BoolObjectClosure {
3813 G1CollectedHeap* _g1;
3814 public:
3815 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3816 bool do_object_b(oop p) {
3817 if (p != NULL) {
3818 return true;
3819 }
3820 return false;
3821 }
3822 };
3823
3824 bool G1STWIsAliveClosure::do_object_b(oop p) {
3825 // An object is reachable if it is outside the collection set,
3826 // or is inside and copied.
3827 return !_g1->is_in_cset(p) || p->is_forwarded();
3828 }
3829
3830 // Non Copying Keep Alive closure
3831 class G1KeepAliveClosure: public OopClosure {
3832 G1CollectedHeap* _g1;
3833 public:
3834 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3835 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3836 void do_oop(oop* p) {
3837 oop obj = *p;
3838 assert(obj != NULL, "the caller should have filtered out NULL values");
3839
3840 const InCSetState cset_state = _g1->in_cset_state(obj);
3841 if (!cset_state.is_in_cset_or_humongous()) {
3842 return;
3843 }
3844 if (cset_state.is_in_cset()) {
3845 assert( obj->is_forwarded(), "invariant" );
3846 *p = obj->forwardee();
3847 } else {
3848 assert(!obj->is_forwarded(), "invariant" );
3849 assert(cset_state.is_humongous(),
3850 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3851 _g1->set_humongous_is_live(obj);
3852 }
3853 }
3854 };
3855
3856 // Copying Keep Alive closure - can be called from both
3857 // serial and parallel code as long as different worker
3858 // threads utilize different G1ParScanThreadState instances
3859 // and different queues.
3860
3861 class G1CopyingKeepAliveClosure: public OopClosure {
3862 G1CollectedHeap* _g1h;
3863 OopClosure* _copy_non_heap_obj_cl;
3864 G1ParScanThreadState* _par_scan_state;
3865
3866 public:
3867 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3868 OopClosure* non_heap_obj_cl,
3869 G1ParScanThreadState* pss):
3870 _g1h(g1h),
3871 _copy_non_heap_obj_cl(non_heap_obj_cl),
3872 _par_scan_state(pss)
3873 {}
3874
3875 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3876 virtual void do_oop( oop* p) { do_oop_work(p); }
3877
3878 template <class T> void do_oop_work(T* p) {
3879 oop obj = oopDesc::load_decode_heap_oop(p);
3880
3881 if (_g1h->is_in_cset_or_humongous(obj)) {
3882 // If the referent object has been forwarded (either copied
3883 // to a new location or to itself in the event of an
3884 // evacuation failure) then we need to update the reference
3885 // field and, if both reference and referent are in the G1
3886 // heap, update the RSet for the referent.
3887 //
3888 // If the referent has not been forwarded then we have to keep
3889 // it alive by policy. Therefore we have copy the referent.
3890 //
3891 // If the reference field is in the G1 heap then we can push
3892 // on the PSS queue. When the queue is drained (after each
3893 // phase of reference processing) the object and it's followers
3894 // will be copied, the reference field set to point to the
3895 // new location, and the RSet updated. Otherwise we need to
3896 // use the the non-heap or metadata closures directly to copy
3897 // the referent object and update the pointer, while avoiding
3898 // updating the RSet.
3899
3900 if (_g1h->is_in_g1_reserved(p)) {
3901 _par_scan_state->push_on_queue(p);
3902 } else {
3903 assert(!Metaspace::contains((const void*)p),
3904 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3905 _copy_non_heap_obj_cl->do_oop(p);
3906 }
3907 }
3908 }
3909 };
3910
3911 // Serial drain queue closure. Called as the 'complete_gc'
3912 // closure for each discovered list in some of the
3913 // reference processing phases.
3914
3915 class G1STWDrainQueueClosure: public VoidClosure {
3916 protected:
3917 G1CollectedHeap* _g1h;
3918 G1ParScanThreadState* _par_scan_state;
3919
3920 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3921
3922 public:
3923 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3924 _g1h(g1h),
3925 _par_scan_state(pss)
3926 { }
3927
3928 void do_void() {
3929 G1ParScanThreadState* const pss = par_scan_state();
3930 pss->trim_queue();
3931 }
3932 };
3933
3934 // Parallel Reference Processing closures
3935
3936 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3937 // processing during G1 evacuation pauses.
3938
3939 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3940 private:
3941 G1CollectedHeap* _g1h;
3942 G1ParScanThreadStateSet* _pss;
3943 RefToScanQueueSet* _queues;
3944 WorkGang* _workers;
3945 uint _active_workers;
3946
3947 public:
3948 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3949 G1ParScanThreadStateSet* per_thread_states,
3950 WorkGang* workers,
3951 RefToScanQueueSet *task_queues,
3952 uint n_workers) :
3953 _g1h(g1h),
3954 _pss(per_thread_states),
3955 _queues(task_queues),
3956 _workers(workers),
3957 _active_workers(n_workers)
3958 {
3959 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3960 }
3961
3962 // Executes the given task using concurrent marking worker threads.
3963 virtual void execute(ProcessTask& task);
3964 virtual void execute(EnqueueTask& task);
3965 };
3966
3967 // Gang task for possibly parallel reference processing
3968
3969 class G1STWRefProcTaskProxy: public AbstractGangTask {
3970 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3971 ProcessTask& _proc_task;
3972 G1CollectedHeap* _g1h;
3973 G1ParScanThreadStateSet* _pss;
3974 RefToScanQueueSet* _task_queues;
3975 ParallelTaskTerminator* _terminator;
3976
3977 public:
3978 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3979 G1CollectedHeap* g1h,
3980 G1ParScanThreadStateSet* per_thread_states,
3981 RefToScanQueueSet *task_queues,
3982 ParallelTaskTerminator* terminator) :
3983 AbstractGangTask("Process reference objects in parallel"),
3984 _proc_task(proc_task),
3985 _g1h(g1h),
3986 _pss(per_thread_states),
3987 _task_queues(task_queues),
3988 _terminator(terminator)
3989 {}
3990
3991 virtual void work(uint worker_id) {
3992 // The reference processing task executed by a single worker.
3993 ResourceMark rm;
3994 HandleMark hm;
3995
3996 G1STWIsAliveClosure is_alive(_g1h);
3997
3998 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3999 pss->set_ref_processor(NULL);
4000
4001 // Keep alive closure.
4002 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4003
4004 // Complete GC closure
4005 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4006
4007 // Call the reference processing task's work routine.
4008 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4009
4010 // Note we cannot assert that the refs array is empty here as not all
4011 // of the processing tasks (specifically phase2 - pp2_work) execute
4012 // the complete_gc closure (which ordinarily would drain the queue) so
4013 // the queue may not be empty.
4014 }
4015 };
4016
4017 // Driver routine for parallel reference processing.
4018 // Creates an instance of the ref processing gang
4019 // task and has the worker threads execute it.
4020 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4021 assert(_workers != NULL, "Need parallel worker threads.");
4022
4023 ParallelTaskTerminator terminator(_active_workers, _queues);
4024 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4025
4026 _workers->run_task(&proc_task_proxy);
4027 }
4028
4029 // Gang task for parallel reference enqueueing.
4030
4031 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4032 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4033 EnqueueTask& _enq_task;
4034
4035 public:
4036 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4037 AbstractGangTask("Enqueue reference objects in parallel"),
4038 _enq_task(enq_task)
4039 { }
4040
4041 virtual void work(uint worker_id) {
4042 _enq_task.work(worker_id);
4043 }
4044 };
4045
4046 // Driver routine for parallel reference enqueueing.
4047 // Creates an instance of the ref enqueueing gang
4048 // task and has the worker threads execute it.
4049
4050 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4051 assert(_workers != NULL, "Need parallel worker threads.");
4052
4053 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4054
4055 _workers->run_task(&enq_task_proxy);
4056 }
4057
4058 // End of weak reference support closures
4059
4060 // Abstract task used to preserve (i.e. copy) any referent objects
4061 // that are in the collection set and are pointed to by reference
4062 // objects discovered by the CM ref processor.
4063
4064 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4065 protected:
4066 G1CollectedHeap* _g1h;
4067 G1ParScanThreadStateSet* _pss;
4068 RefToScanQueueSet* _queues;
4069 ParallelTaskTerminator _terminator;
4070 uint _n_workers;
4071
4072 public:
4073 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4074 AbstractGangTask("ParPreserveCMReferents"),
4075 _g1h(g1h),
4076 _pss(per_thread_states),
4077 _queues(task_queues),
4078 _terminator(workers, _queues),
4079 _n_workers(workers)
4080 {
4081 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4082 }
4083
4084 void work(uint worker_id) {
4085 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4086
4087 ResourceMark rm;
4088 HandleMark hm;
4089
4090 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4091 pss->set_ref_processor(NULL);
4092 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4093
4094 // Is alive closure
4095 G1AlwaysAliveClosure always_alive(_g1h);
4096
4097 // Copying keep alive closure. Applied to referent objects that need
4098 // to be copied.
4099 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4100
4101 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4102
4103 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4104 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4105
4106 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4107 // So this must be true - but assert just in case someone decides to
4108 // change the worker ids.
4109 assert(worker_id < limit, "sanity");
4110 assert(!rp->discovery_is_atomic(), "check this code");
4111
4112 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4113 for (uint idx = worker_id; idx < limit; idx += stride) {
4114 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4115
4116 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4117 while (iter.has_next()) {
4118 // Since discovery is not atomic for the CM ref processor, we
4119 // can see some null referent objects.
4120 iter.load_ptrs(DEBUG_ONLY(true));
4121 oop ref = iter.obj();
4122
4123 // This will filter nulls.
4124 if (iter.is_referent_alive()) {
4125 iter.make_referent_alive();
4126 }
4127 iter.move_to_next();
4128 }
4129 }
4130
4131 // Drain the queue - which may cause stealing
4132 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4133 drain_queue.do_void();
4134 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4135 assert(pss->queue_is_empty(), "should be");
4136 }
4137 };
4138
4139 void G1CollectedHeap::process_weak_jni_handles() {
4140 double ref_proc_start = os::elapsedTime();
4141
4142 G1STWIsAliveClosure is_alive(this);
4143 G1KeepAliveClosure keep_alive(this);
4144 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4145
4146 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4147 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4148 }
4149
4150 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4151 // Any reference objects, in the collection set, that were 'discovered'
4152 // by the CM ref processor should have already been copied (either by
4153 // applying the external root copy closure to the discovered lists, or
4154 // by following an RSet entry).
4155 //
4156 // But some of the referents, that are in the collection set, that these
4157 // reference objects point to may not have been copied: the STW ref
4158 // processor would have seen that the reference object had already
4159 // been 'discovered' and would have skipped discovering the reference,
4160 // but would not have treated the reference object as a regular oop.
4161 // As a result the copy closure would not have been applied to the
4162 // referent object.
4163 //
4164 // We need to explicitly copy these referent objects - the references
4165 // will be processed at the end of remarking.
4166 //
4167 // We also need to do this copying before we process the reference
4168 // objects discovered by the STW ref processor in case one of these
4169 // referents points to another object which is also referenced by an
4170 // object discovered by the STW ref processor.
4171 double preserve_cm_referents_time = 0.0;
4172
4173 // To avoid spawning task when there is no work to do, check that
4174 // a concurrent cycle is active and that some references have been
4175 // discovered.
4176 if (concurrent_mark()->cmThread()->during_cycle() &&
4177 ref_processor_cm()->has_discovered_references()) {
4178 double preserve_cm_referents_start = os::elapsedTime();
4179 uint no_of_gc_workers = workers()->active_workers();
4180 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4181 per_thread_states,
4182 no_of_gc_workers,
4183 _task_queues);
4184 workers()->run_task(&keep_cm_referents);
4185 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4186 }
4187
4188 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4189 }
4190
4191 // Weak Reference processing during an evacuation pause (part 1).
4192 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4193 double ref_proc_start = os::elapsedTime();
4194
4195 ReferenceProcessor* rp = _ref_processor_stw;
4196 assert(rp->discovery_enabled(), "should have been enabled");
4197
4198 // Closure to test whether a referent is alive.
4199 G1STWIsAliveClosure is_alive(this);
4200
4201 // Even when parallel reference processing is enabled, the processing
4202 // of JNI refs is serial and performed serially by the current thread
4203 // rather than by a worker. The following PSS will be used for processing
4204 // JNI refs.
4205
4206 // Use only a single queue for this PSS.
4207 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4208 pss->set_ref_processor(NULL);
4209 assert(pss->queue_is_empty(), "pre-condition");
4210
4211 // Keep alive closure.
4212 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4213
4214 // Serial Complete GC closure
4215 G1STWDrainQueueClosure drain_queue(this, pss);
4216
4217 // Setup the soft refs policy...
4218 rp->setup_policy(false);
4219
4220 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4221
4222 ReferenceProcessorStats stats;
4223 if (!rp->processing_is_mt()) {
4224 // Serial reference processing...
4225 stats = rp->process_discovered_references(&is_alive,
4226 &keep_alive,
4227 &drain_queue,
4228 NULL,
4229 pt);
4230 } else {
4231 uint no_of_gc_workers = workers()->active_workers();
4232
4233 // Parallel reference processing
4234 assert(no_of_gc_workers <= rp->max_num_q(),
4235 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4236 no_of_gc_workers, rp->max_num_q());
4237
4238 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4239 stats = rp->process_discovered_references(&is_alive,
4240 &keep_alive,
4241 &drain_queue,
4242 &par_task_executor,
4243 pt);
4244 }
4245
4246 _gc_tracer_stw->report_gc_reference_stats(stats);
4247
4248 // We have completed copying any necessary live referent objects.
4249 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4250
4251 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4252 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4253 }
4254
4255 // Weak Reference processing during an evacuation pause (part 2).
4256 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4257 double ref_enq_start = os::elapsedTime();
4258
4259 ReferenceProcessor* rp = _ref_processor_stw;
4260 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4261
4262 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4263
4264 // Now enqueue any remaining on the discovered lists on to
4265 // the pending list.
4266 if (!rp->processing_is_mt()) {
4267 // Serial reference processing...
4268 rp->enqueue_discovered_references(NULL, pt);
4269 } else {
4270 // Parallel reference enqueueing
4271
4272 uint n_workers = workers()->active_workers();
4273
4274 assert(n_workers <= rp->max_num_q(),
4275 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4276 n_workers, rp->max_num_q());
4277
4278 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4279 rp->enqueue_discovered_references(&par_task_executor, pt);
4280 }
4281
4282 rp->verify_no_references_recorded();
4283 assert(!rp->discovery_enabled(), "should have been disabled");
4284
4285 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4286 // ensure that it is marked in the bitmap for concurrent marking to discover.
4287 if (collector_state()->during_initial_mark_pause()) {
4288 oop pll_head = Universe::reference_pending_list();
4289 if (pll_head != NULL) {
4290 _cm->mark_in_next_bitmap(pll_head);
4291 }
4292 }
4293
4294 // FIXME
4295 // CM's reference processing also cleans up the string and symbol tables.
4296 // Should we do that here also? We could, but it is a serial operation
4297 // and could significantly increase the pause time.
4298
4299 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4300 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4301 }
4302
4303 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4304 double merge_pss_time_start = os::elapsedTime();
4305 per_thread_states->flush();
4306 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4307 }
4308
4309 void G1CollectedHeap::pre_evacuate_collection_set() {
4310 _expand_heap_after_alloc_failure = true;
4311 _evacuation_failed = false;
4312
4313 // Disable the hot card cache.
4314 _hot_card_cache->reset_hot_cache_claimed_index();
4315 _hot_card_cache->set_use_cache(false);
4316
4317 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4318 _preserved_marks_set.assert_empty();
4319
4320 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4321
4322 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4323 if (collector_state()->during_initial_mark_pause()) {
4324 double start_clear_claimed_marks = os::elapsedTime();
4325
4326 ClassLoaderDataGraph::clear_claimed_marks();
4327
4328 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4329 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4330 }
4331 }
4332
4333 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4334 // Should G1EvacuationFailureALot be in effect for this GC?
4335 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4336
4337 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4338
4339 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4340
4341 double start_par_time_sec = os::elapsedTime();
4342 double end_par_time_sec;
4343
4344 {
4345 const uint n_workers = workers()->active_workers();
4346 G1RootProcessor root_processor(this, n_workers);
4347 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4348
4349 print_termination_stats_hdr();
4350
4351 workers()->run_task(&g1_par_task);
4352 end_par_time_sec = os::elapsedTime();
4353
4354 // Closing the inner scope will execute the destructor
4355 // for the G1RootProcessor object. We record the current
4356 // elapsed time before closing the scope so that time
4357 // taken for the destructor is NOT included in the
4358 // reported parallel time.
4359 }
4360
4361 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4362 phase_times->record_par_time(par_time_ms);
4363
4364 double code_root_fixup_time_ms =
4365 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4366 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4367 }
4368
4369 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4370 // Process any discovered reference objects - we have
4371 // to do this _before_ we retire the GC alloc regions
4372 // as we may have to copy some 'reachable' referent
4373 // objects (and their reachable sub-graphs) that were
4374 // not copied during the pause.
4375 if (g1_policy()->should_process_references()) {
4376 preserve_cm_referents(per_thread_states);
4377 process_discovered_references(per_thread_states);
4378 } else {
4379 ref_processor_stw()->verify_no_references_recorded();
4380 process_weak_jni_handles();
4381 }
4382
4383 if (G1StringDedup::is_enabled()) {
4384 double fixup_start = os::elapsedTime();
4385
4386 G1STWIsAliveClosure is_alive(this);
4387 G1KeepAliveClosure keep_alive(this);
4388 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4389
4390 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4391 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4392 }
4393
4394 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4395
4396 if (evacuation_failed()) {
4397 restore_after_evac_failure();
4398
4399 // Reset the G1EvacuationFailureALot counters and flags
4400 // Note: the values are reset only when an actual
4401 // evacuation failure occurs.
4402 NOT_PRODUCT(reset_evacuation_should_fail();)
4403 }
4404
4405 _preserved_marks_set.assert_empty();
4406
4407 // Enqueue any remaining references remaining on the STW
4408 // reference processor's discovered lists. We need to do
4409 // this after the card table is cleaned (and verified) as
4410 // the act of enqueueing entries on to the pending list
4411 // will log these updates (and dirty their associated
4412 // cards). We need these updates logged to update any
4413 // RSets.
4414 if (g1_policy()->should_process_references()) {
4415 enqueue_discovered_references(per_thread_states);
4416 } else {
4417 g1_policy()->phase_times()->record_ref_enq_time(0);
4418 }
4419
4420 _allocator->release_gc_alloc_regions(evacuation_info);
4421
4422 merge_per_thread_state_info(per_thread_states);
4423
4424 // Reset and re-enable the hot card cache.
4425 // Note the counts for the cards in the regions in the
4426 // collection set are reset when the collection set is freed.
4427 _hot_card_cache->reset_hot_cache();
4428 _hot_card_cache->set_use_cache(true);
4429
4430 purge_code_root_memory();
4431
4432 redirty_logged_cards();
4433 #if defined(COMPILER2) || INCLUDE_JVMCI
4434 double start = os::elapsedTime();
4435 DerivedPointerTable::update_pointers();
4436 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4437 #endif
4438 g1_policy()->print_age_table();
4439 }
4440
4441 void G1CollectedHeap::record_obj_copy_mem_stats() {
4442 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4443
4444 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4445 create_g1_evac_summary(&_old_evac_stats));
4446 }
4447
4448 void G1CollectedHeap::free_region(HeapRegion* hr,
4449 FreeRegionList* free_list,
4450 bool skip_remset,
4451 bool skip_hot_card_cache,
4452 bool locked) {
4453 assert(!hr->is_free(), "the region should not be free");
4454 assert(!hr->is_empty(), "the region should not be empty");
4455 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4456 assert(free_list != NULL, "pre-condition");
4457
4458 if (G1VerifyBitmaps) {
4459 MemRegion mr(hr->bottom(), hr->end());
4460 concurrent_mark()->clearRangePrevBitmap(mr);
4461 }
4462
4463 // Clear the card counts for this region.
4464 // Note: we only need to do this if the region is not young
4465 // (since we don't refine cards in young regions).
4466 if (!skip_hot_card_cache && !hr->is_young()) {
4467 _hot_card_cache->reset_card_counts(hr);
4468 }
4469 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4470 free_list->add_ordered(hr);
4471 }
4472
4473 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4474 FreeRegionList* free_list,
4475 bool skip_remset) {
4476 assert(hr->is_humongous(), "this is only for humongous regions");
4477 assert(free_list != NULL, "pre-condition");
4478 hr->clear_humongous();
4479 free_region(hr, free_list, skip_remset);
4480 }
4481
4482 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4483 const uint humongous_regions_removed) {
4484 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4485 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4486 _old_set.bulk_remove(old_regions_removed);
4487 _humongous_set.bulk_remove(humongous_regions_removed);
4488 }
4489
4490 }
4491
4492 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4493 assert(list != NULL, "list can't be null");
4494 if (!list->is_empty()) {
4495 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4496 _hrm.insert_list_into_free_list(list);
4497 }
4498 }
4499
4500 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4501 decrease_used(bytes);
4502 }
4503
4504 class G1ParScrubRemSetTask: public AbstractGangTask {
4505 protected:
4506 G1RemSet* _g1rs;
4507 HeapRegionClaimer _hrclaimer;
4508
4509 public:
4510 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4511 AbstractGangTask("G1 ScrubRS"),
4512 _g1rs(g1_rs),
4513 _hrclaimer(num_workers) {
4514 }
4515
4516 void work(uint worker_id) {
4517 _g1rs->scrub(worker_id, &_hrclaimer);
4518 }
4519 };
4520
4521 void G1CollectedHeap::scrub_rem_set() {
4522 uint num_workers = workers()->active_workers();
4523 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4524 workers()->run_task(&g1_par_scrub_rs_task);
4525 }
4526
4527 class G1FreeCollectionSetTask : public AbstractGangTask {
4528 private:
4529
4530 // Closure applied to all regions in the collection set to do work that needs to
4531 // be done serially in a single thread.
4532 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4533 private:
4534 EvacuationInfo* _evacuation_info;
4535 const size_t* _surviving_young_words;
4536
4537 // Bytes used in successfully evacuated regions before the evacuation.
4538 size_t _before_used_bytes;
4539 // Bytes used in unsucessfully evacuated regions before the evacuation
4540 size_t _after_used_bytes;
4541
4542 size_t _bytes_allocated_in_old_since_last_gc;
4543
4544 size_t _failure_used_words;
4545 size_t _failure_waste_words;
4546
4547 FreeRegionList _local_free_list;
4548 public:
4549 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4550 HeapRegionClosure(),
4551 _evacuation_info(evacuation_info),
4552 _surviving_young_words(surviving_young_words),
4553 _before_used_bytes(0),
4554 _after_used_bytes(0),
4555 _bytes_allocated_in_old_since_last_gc(0),
4556 _failure_used_words(0),
4557 _failure_waste_words(0),
4558 _local_free_list("Local Region List for CSet Freeing") {
4559 }
4560
4561 virtual bool doHeapRegion(HeapRegion* r) {
4562 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4563
4564 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4565 g1h->clear_in_cset(r);
4566
4567 if (r->is_young()) {
4568 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4569 "Young index %d is wrong for region %u of type %s with %u young regions",
4570 r->young_index_in_cset(),
4571 r->hrm_index(),
4572 r->get_type_str(),
4573 g1h->collection_set()->young_region_length());
4574 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4575 r->record_surv_words_in_group(words_survived);
4576 }
4577
4578 if (!r->evacuation_failed()) {
4579 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4580 _before_used_bytes += r->used();
4581 g1h->free_region(r,
4582 &_local_free_list,
4583 true, /* skip_remset */
4584 true, /* skip_hot_card_cache */
4585 true /* locked */);
4586 } else {
4587 r->uninstall_surv_rate_group();
4588 r->set_young_index_in_cset(-1);
4589 r->set_evacuation_failed(false);
4590 // When moving a young gen region to old gen, we "allocate" that whole region
4591 // there. This is in addition to any already evacuated objects. Notify the
4592 // policy about that.
4593 // Old gen regions do not cause an additional allocation: both the objects
4594 // still in the region and the ones already moved are accounted for elsewhere.
4595 if (r->is_young()) {
4596 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4597 }
4598 // The region is now considered to be old.
4599 r->set_old();
4600 // Do some allocation statistics accounting. Regions that failed evacuation
4601 // are always made old, so there is no need to update anything in the young
4602 // gen statistics, but we need to update old gen statistics.
4603 size_t used_words = r->marked_bytes() / HeapWordSize;
4604
4605 _failure_used_words += used_words;
4606 _failure_waste_words += HeapRegion::GrainWords - used_words;
4607
4608 g1h->old_set_add(r);
4609 _after_used_bytes += r->used();
4610 }
4611 return false;
4612 }
4613
4614 void complete_work() {
4615 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4616
4617 _evacuation_info->set_regions_freed(_local_free_list.length());
4618 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4619
4620 g1h->prepend_to_freelist(&_local_free_list);
4621 g1h->decrement_summary_bytes(_before_used_bytes);
4622
4623 G1Policy* policy = g1h->g1_policy();
4624 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4625
4626 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4627 }
4628 };
4629
4630 G1CollectionSet* _collection_set;
4631 G1SerialFreeCollectionSetClosure _cl;
4632 const size_t* _surviving_young_words;
4633
4634 size_t _rs_lengths;
4635
4636 volatile jint _serial_work_claim;
4637
4638 struct WorkItem {
4639 uint region_idx;
4640 bool is_young;
4641 bool evacuation_failed;
4642
4643 WorkItem(HeapRegion* r) {
4644 region_idx = r->hrm_index();
4645 is_young = r->is_young();
4646 evacuation_failed = r->evacuation_failed();
4647 }
4648 };
4649
4650 volatile size_t _parallel_work_claim;
4651 size_t _num_work_items;
4652 WorkItem* _work_items;
4653
4654 void do_serial_work() {
4655 // Need to grab the lock to be allowed to modify the old region list.
4656 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4657 _collection_set->iterate(&_cl);
4658 }
4659
4660 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4661 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4662
4663 HeapRegion* r = g1h->region_at(region_idx);
4664 assert(!g1h->is_on_master_free_list(r), "sanity");
4665
4666 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4667
4668 if (!is_young) {
4669 g1h->_hot_card_cache->reset_card_counts(r);
4670 }
4671
4672 if (!evacuation_failed) {
4673 r->rem_set()->clear_locked();
4674 }
4675 }
4676
4677 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4678 private:
4679 size_t _cur_idx;
4680 WorkItem* _work_items;
4681 public:
4682 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4683
4684 virtual bool doHeapRegion(HeapRegion* r) {
4685 _work_items[_cur_idx++] = WorkItem(r);
4686 return false;
4687 }
4688 };
4689
4690 void prepare_work() {
4691 G1PrepareFreeCollectionSetClosure cl(_work_items);
4692 _collection_set->iterate(&cl);
4693 }
4694
4695 void complete_work() {
4696 _cl.complete_work();
4697
4698 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4699 policy->record_max_rs_lengths(_rs_lengths);
4700 policy->cset_regions_freed();
4701 }
4702 public:
4703 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4704 AbstractGangTask("G1 Free Collection Set"),
4705 _cl(evacuation_info, surviving_young_words),
4706 _collection_set(collection_set),
4707 _surviving_young_words(surviving_young_words),
4708 _serial_work_claim(0),
4709 _rs_lengths(0),
4710 _parallel_work_claim(0),
4711 _num_work_items(collection_set->region_length()),
4712 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4713 prepare_work();
4714 }
4715
4716 ~G1FreeCollectionSetTask() {
4717 complete_work();
4718 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4719 }
4720
4721 // Chunk size for work distribution. The chosen value has been determined experimentally
4722 // to be a good tradeoff between overhead and achievable parallelism.
4723 static uint chunk_size() { return 32; }
4724
4725 virtual void work(uint worker_id) {
4726 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4727
4728 // Claim serial work.
4729 if (_serial_work_claim == 0) {
4730 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4731 if (value == 0) {
4732 double serial_time = os::elapsedTime();
4733 do_serial_work();
4734 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4735 }
4736 }
4737
4738 // Start parallel work.
4739 double young_time = 0.0;
4740 bool has_young_time = false;
4741 double non_young_time = 0.0;
4742 bool has_non_young_time = false;
4743
4744 while (true) {
4745 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4746 size_t cur = end - chunk_size();
4747
4748 if (cur >= _num_work_items) {
4749 break;
4750 }
4751
4752 double start_time = os::elapsedTime();
4753
4754 end = MIN2(end, _num_work_items);
4755
4756 for (; cur < end; cur++) {
4757 bool is_young = _work_items[cur].is_young;
4758
4759 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4760
4761 double end_time = os::elapsedTime();
4762 double time_taken = end_time - start_time;
4763 if (is_young) {
4764 young_time += time_taken;
4765 has_young_time = true;
4766 } else {
4767 non_young_time += time_taken;
4768 has_non_young_time = true;
4769 }
4770 start_time = end_time;
4771 }
4772 }
4773
4774 if (has_young_time) {
4775 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4776 }
4777 if (has_non_young_time) {
4778 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4779 }
4780 }
4781 };
4782
4783 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4784 _eden.clear();
4785
4786 double free_cset_start_time = os::elapsedTime();
4787
4788 {
4789 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4790 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4791
4792 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4793
4794 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4795 cl.name(),
4796 num_workers,
4797 _collection_set.region_length());
4798 workers()->run_task(&cl, num_workers);
4799 }
4800 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4801
4802 collection_set->clear();
4803 }
4804
4805 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4806 private:
4807 FreeRegionList* _free_region_list;
4808 HeapRegionSet* _proxy_set;
4809 uint _humongous_objects_reclaimed;
4810 uint _humongous_regions_reclaimed;
4811 size_t _freed_bytes;
4812 public:
4813
4814 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4815 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4816 }
4817
4818 virtual bool doHeapRegion(HeapRegion* r) {
4819 if (!r->is_starts_humongous()) {
4820 return false;
4821 }
4822
4823 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4824
4825 oop obj = (oop)r->bottom();
4826 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4827
4828 // The following checks whether the humongous object is live are sufficient.
4829 // The main additional check (in addition to having a reference from the roots
4830 // or the young gen) is whether the humongous object has a remembered set entry.
4831 //
4832 // A humongous object cannot be live if there is no remembered set for it
4833 // because:
4834 // - there can be no references from within humongous starts regions referencing
4835 // the object because we never allocate other objects into them.
4836 // (I.e. there are no intra-region references that may be missed by the
4837 // remembered set)
4838 // - as soon there is a remembered set entry to the humongous starts region
4839 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4840 // until the end of a concurrent mark.
4841 //
4842 // It is not required to check whether the object has been found dead by marking
4843 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4844 // all objects allocated during that time are considered live.
4845 // SATB marking is even more conservative than the remembered set.
4846 // So if at this point in the collection there is no remembered set entry,
4847 // nobody has a reference to it.
4848 // At the start of collection we flush all refinement logs, and remembered sets
4849 // are completely up-to-date wrt to references to the humongous object.
4850 //
4851 // Other implementation considerations:
4852 // - never consider object arrays at this time because they would pose
4853 // considerable effort for cleaning up the the remembered sets. This is
4854 // required because stale remembered sets might reference locations that
4855 // are currently allocated into.
4856 uint region_idx = r->hrm_index();
4857 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4858 !r->rem_set()->is_empty()) {
4859 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",
4860 region_idx,
4861 (size_t)obj->size() * HeapWordSize,
4862 p2i(r->bottom()),
4863 r->rem_set()->occupied(),
4864 r->rem_set()->strong_code_roots_list_length(),
4865 next_bitmap->is_marked(r->bottom()),
4866 g1h->is_humongous_reclaim_candidate(region_idx),
4867 obj->is_typeArray()
4868 );
4869 return false;
4870 }
4871
4872 guarantee(obj->is_typeArray(),
4873 "Only eagerly reclaiming type arrays is supported, but the object "
4874 PTR_FORMAT " is not.", p2i(r->bottom()));
4875
4876 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",
4877 region_idx,
4878 (size_t)obj->size() * HeapWordSize,
4879 p2i(r->bottom()),
4880 r->rem_set()->occupied(),
4881 r->rem_set()->strong_code_roots_list_length(),
4882 next_bitmap->is_marked(r->bottom()),
4883 g1h->is_humongous_reclaim_candidate(region_idx),
4884 obj->is_typeArray()
4885 );
4886
4887 // Need to clear mark bit of the humongous object if already set.
4888 if (next_bitmap->is_marked(r->bottom())) {
4889 next_bitmap->clear(r->bottom());
4890 }
4891 _humongous_objects_reclaimed++;
4892 do {
4893 HeapRegion* next = g1h->next_region_in_humongous(r);
4894 _freed_bytes += r->used();
4895 r->set_containing_set(NULL);
4896 _humongous_regions_reclaimed++;
4897 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4898 r = next;
4899 } while (r != NULL);
4900
4901 return false;
4902 }
4903
4904 uint humongous_objects_reclaimed() {
4905 return _humongous_objects_reclaimed;
4906 }
4907
4908 uint humongous_regions_reclaimed() {
4909 return _humongous_regions_reclaimed;
4910 }
4911
4912 size_t bytes_freed() const {
4913 return _freed_bytes;
4914 }
4915 };
4916
4917 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4918 assert_at_safepoint(true);
4919
4920 if (!G1EagerReclaimHumongousObjects ||
4921 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4922 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4923 return;
4924 }
4925
4926 double start_time = os::elapsedTime();
4927
4928 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4929
4930 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4931 heap_region_iterate(&cl);
4932
4933 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4934
4935 G1HRPrinter* hrp = hr_printer();
4936 if (hrp->is_active()) {
4937 FreeRegionListIterator iter(&local_cleanup_list);
4938 while (iter.more_available()) {
4939 HeapRegion* hr = iter.get_next();
4940 hrp->cleanup(hr);
4941 }
4942 }
4943
4944 prepend_to_freelist(&local_cleanup_list);
4945 decrement_summary_bytes(cl.bytes_freed());
4946
4947 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4948 cl.humongous_objects_reclaimed());
4949 }
4950
4951 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4952 public:
4953 virtual bool doHeapRegion(HeapRegion* r) {
4954 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4955 G1CollectedHeap::heap()->clear_in_cset(r);
4956 r->set_young_index_in_cset(-1);
4957 return false;
4958 }
4959 };
4960
4961 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4962 G1AbandonCollectionSetClosure cl;
4963 collection_set->iterate(&cl);
4964
4965 collection_set->clear();
4966 collection_set->stop_incremental_building();
4967 }
4968
4969 void G1CollectedHeap::set_free_regions_coming() {
4970 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4971
4972 assert(!free_regions_coming(), "pre-condition");
4973 _free_regions_coming = true;
4974 }
4975
4976 void G1CollectedHeap::reset_free_regions_coming() {
4977 assert(free_regions_coming(), "pre-condition");
4978
4979 {
4980 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4981 _free_regions_coming = false;
4982 SecondaryFreeList_lock->notify_all();
4983 }
4984
4985 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4986 }
4987
4988 void G1CollectedHeap::wait_while_free_regions_coming() {
4989 // Most of the time we won't have to wait, so let's do a quick test
4990 // first before we take the lock.
4991 if (!free_regions_coming()) {
4992 return;
4993 }
4994
4995 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4996
4997 {
4998 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4999 while (free_regions_coming()) {
5000 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5001 }
5002 }
5003
5004 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5005 }
5006
5007 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5008 return _allocator->is_retained_old_region(hr);
5009 }
5010
5011 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5012 _eden.add(hr);
5013 _g1_policy->set_region_eden(hr);
5014 }
5015
5016 #ifdef ASSERT
5017
5018 class NoYoungRegionsClosure: public HeapRegionClosure {
5019 private:
5020 bool _success;
5021 public:
5022 NoYoungRegionsClosure() : _success(true) { }
5023 bool doHeapRegion(HeapRegion* r) {
5024 if (r->is_young()) {
5025 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5026 p2i(r->bottom()), p2i(r->end()));
5027 _success = false;
5028 }
5029 return false;
5030 }
5031 bool success() { return _success; }
5032 };
5033
5034 bool G1CollectedHeap::check_young_list_empty() {
5035 bool ret = (young_regions_count() == 0);
5036
5037 NoYoungRegionsClosure closure;
5038 heap_region_iterate(&closure);
5039 ret = ret && closure.success();
5040
5041 return ret;
5042 }
5043
5044 #endif // ASSERT
5045
5046 class TearDownRegionSetsClosure : public HeapRegionClosure {
5047 private:
5048 HeapRegionSet *_old_set;
5049
5050 public:
5051 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5052
5053 bool doHeapRegion(HeapRegion* r) {
5054 if (r->is_old()) {
5055 _old_set->remove(r);
5056 } else if(r->is_young()) {
5057 r->uninstall_surv_rate_group();
5058 } else {
5059 // We ignore free regions, we'll empty the free list afterwards.
5060 // We ignore humongous regions, we're not tearing down the
5061 // humongous regions set.
5062 assert(r->is_free() || r->is_humongous(),
5063 "it cannot be another type");
5064 }
5065 return false;
5066 }
5067
5068 ~TearDownRegionSetsClosure() {
5069 assert(_old_set->is_empty(), "post-condition");
5070 }
5071 };
5072
5073 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5074 assert_at_safepoint(true /* should_be_vm_thread */);
5075
5076 if (!free_list_only) {
5077 TearDownRegionSetsClosure cl(&_old_set);
5078 heap_region_iterate(&cl);
5079
5080 // Note that emptying the _young_list is postponed and instead done as
5081 // the first step when rebuilding the regions sets again. The reason for
5082 // this is that during a full GC string deduplication needs to know if
5083 // a collected region was young or old when the full GC was initiated.
5084 }
5085 _hrm.remove_all_free_regions();
5086 }
5087
5088 void G1CollectedHeap::increase_used(size_t bytes) {
5089 _summary_bytes_used += bytes;
5090 }
5091
5092 void G1CollectedHeap::decrease_used(size_t bytes) {
5093 assert(_summary_bytes_used >= bytes,
5094 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5095 _summary_bytes_used, bytes);
5096 _summary_bytes_used -= bytes;
5097 }
5098
5099 void G1CollectedHeap::set_used(size_t bytes) {
5100 _summary_bytes_used = bytes;
5101 }
5102
5103 class RebuildRegionSetsClosure : public HeapRegionClosure {
5104 private:
5105 bool _free_list_only;
5106 HeapRegionSet* _old_set;
5107 HeapRegionManager* _hrm;
5108 size_t _total_used;
5109
5110 public:
5111 RebuildRegionSetsClosure(bool free_list_only,
5112 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5113 _free_list_only(free_list_only),
5114 _old_set(old_set), _hrm(hrm), _total_used(0) {
5115 assert(_hrm->num_free_regions() == 0, "pre-condition");
5116 if (!free_list_only) {
5117 assert(_old_set->is_empty(), "pre-condition");
5118 }
5119 }
5120
5121 bool doHeapRegion(HeapRegion* r) {
5122 if (r->is_empty()) {
5123 // Add free regions to the free list
5124 r->set_free();
5125 r->set_allocation_context(AllocationContext::system());
5126 _hrm->insert_into_free_list(r);
5127 } else if (!_free_list_only) {
5128
5129 if (r->is_humongous()) {
5130 // We ignore humongous regions. We left the humongous set unchanged.
5131 } else {
5132 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5133 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5134 r->move_to_old();
5135 _old_set->add(r);
5136 }
5137 _total_used += r->used();
5138 }
5139
5140 return false;
5141 }
5142
5143 size_t total_used() {
5144 return _total_used;
5145 }
5146 };
5147
5148 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5149 assert_at_safepoint(true /* should_be_vm_thread */);
5150
5151 if (!free_list_only) {
5152 _eden.clear();
5153 _survivor.clear();
5154 }
5155
5156 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5157 heap_region_iterate(&cl);
5158
5159 if (!free_list_only) {
5160 set_used(cl.total_used());
5161 if (_archive_allocator != NULL) {
5162 _archive_allocator->clear_used();
5163 }
5164 }
5165 assert(used_unlocked() == recalculate_used(),
5166 "inconsistent used_unlocked(), "
5167 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5168 used_unlocked(), recalculate_used());
5169 }
5170
5171 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5172 HeapRegion* hr = heap_region_containing(p);
5173 return hr->is_in(p);
5174 }
5175
5176 // Methods for the mutator alloc region
5177
5178 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5179 bool force) {
5180 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5181 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5182 if (force || should_allocate) {
5183 HeapRegion* new_alloc_region = new_region(word_size,
5184 false /* is_old */,
5185 false /* do_expand */);
5186 if (new_alloc_region != NULL) {
5187 set_region_short_lived_locked(new_alloc_region);
5188 _hr_printer.alloc(new_alloc_region, !should_allocate);
5189 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5190 return new_alloc_region;
5191 }
5192 }
5193 return NULL;
5194 }
5195
5196 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5197 size_t allocated_bytes) {
5198 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5199 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5200
5201 collection_set()->add_eden_region(alloc_region);
5202 increase_used(allocated_bytes);
5203 _hr_printer.retire(alloc_region);
5204 // We update the eden sizes here, when the region is retired,
5205 // instead of when it's allocated, since this is the point that its
5206 // used space has been recored in _summary_bytes_used.
5207 g1mm()->update_eden_size();
5208 }
5209
5210 // Methods for the GC alloc regions
5211
5212 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5213 if (dest.is_old()) {
5214 return true;
5215 } else {
5216 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5217 }
5218 }
5219
5220 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5221 assert(FreeList_lock->owned_by_self(), "pre-condition");
5222
5223 if (!has_more_regions(dest)) {
5224 return NULL;
5225 }
5226
5227 const bool is_survivor = dest.is_young();
5228
5229 HeapRegion* new_alloc_region = new_region(word_size,
5230 !is_survivor,
5231 true /* do_expand */);
5232 if (new_alloc_region != NULL) {
5233 // We really only need to do this for old regions given that we
5234 // should never scan survivors. But it doesn't hurt to do it
5235 // for survivors too.
5236 new_alloc_region->record_timestamp();
5237 if (is_survivor) {
5238 new_alloc_region->set_survivor();
5239 _survivor.add(new_alloc_region);
5240 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5241 } else {
5242 new_alloc_region->set_old();
5243 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5244 }
5245 _hr_printer.alloc(new_alloc_region);
5246 bool during_im = collector_state()->during_initial_mark_pause();
5247 new_alloc_region->note_start_of_copying(during_im);
5248 return new_alloc_region;
5249 }
5250 return NULL;
5251 }
5252
5253 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5254 size_t allocated_bytes,
5255 InCSetState dest) {
5256 bool during_im = collector_state()->during_initial_mark_pause();
5257 alloc_region->note_end_of_copying(during_im);
5258 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5259 if (dest.is_old()) {
5260 _old_set.add(alloc_region);
5261 }
5262 _hr_printer.retire(alloc_region);
5263 }
5264
5265 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5266 bool expanded = false;
5267 uint index = _hrm.find_highest_free(&expanded);
5268
5269 if (index != G1_NO_HRM_INDEX) {
5270 if (expanded) {
5271 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5272 HeapRegion::GrainWords * HeapWordSize);
5273 }
5274 _hrm.allocate_free_regions_starting_at(index, 1);
5275 return region_at(index);
5276 }
5277 return NULL;
5278 }
5279
5280 // Optimized nmethod scanning
5281
5282 class RegisterNMethodOopClosure: public OopClosure {
5283 G1CollectedHeap* _g1h;
5284 nmethod* _nm;
5285
5286 template <class T> void do_oop_work(T* p) {
5287 T heap_oop = oopDesc::load_heap_oop(p);
5288 if (!oopDesc::is_null(heap_oop)) {
5289 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5290 HeapRegion* hr = _g1h->heap_region_containing(obj);
5291 assert(!hr->is_continues_humongous(),
5292 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5293 " starting at " HR_FORMAT,
5294 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5295
5296 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5297 hr->add_strong_code_root_locked(_nm);
5298 }
5299 }
5300
5301 public:
5302 RegisterNMethodOopClosure(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 class UnregisterNMethodOopClosure: public OopClosure {
5310 G1CollectedHeap* _g1h;
5311 nmethod* _nm;
5312
5313 template <class T> void do_oop_work(T* p) {
5314 T heap_oop = oopDesc::load_heap_oop(p);
5315 if (!oopDesc::is_null(heap_oop)) {
5316 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5317 HeapRegion* hr = _g1h->heap_region_containing(obj);
5318 assert(!hr->is_continues_humongous(),
5319 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5320 " starting at " HR_FORMAT,
5321 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5322
5323 hr->remove_strong_code_root(_nm);
5324 }
5325 }
5326
5327 public:
5328 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5329 _g1h(g1h), _nm(nm) {}
5330
5331 void do_oop(oop* p) { do_oop_work(p); }
5332 void do_oop(narrowOop* p) { do_oop_work(p); }
5333 };
5334
5335 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5336 assert_locked_or_safepoint(CodeCache_lock);
5337 guarantee(nm != NULL, "sanity");
5338 RegisterNMethodOopClosure reg_cl(this, nm);
5339 nm->oops_do(®_cl);
5340 }
5341
5342 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5343 assert_locked_or_safepoint(CodeCache_lock);
5344 guarantee(nm != NULL, "sanity");
5345 UnregisterNMethodOopClosure reg_cl(this, nm);
5346 nm->oops_do(®_cl, true);
5347 }
5348
5349 void G1CollectedHeap::purge_code_root_memory() {
5350 double purge_start = os::elapsedTime();
5351 G1CodeRootSet::purge();
5352 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5353 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5354 }
5355
5356 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5357 G1CollectedHeap* _g1h;
5358
5359 public:
5360 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5361 _g1h(g1h) {}
5362
5363 void do_code_blob(CodeBlob* cb) {
5364 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5365 if (nm == NULL) {
5366 return;
5367 }
5368
5369 if (ScavengeRootsInCode) {
5370 _g1h->register_nmethod(nm);
5371 }
5372 }
5373 };
5374
5375 void G1CollectedHeap::rebuild_strong_code_roots() {
5376 RebuildStrongCodeRootClosure blob_cl(this);
5377 CodeCache::blobs_do(&blob_cl);
5378 }