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/heapMonitoring.hpp"
81 #include "runtime/init.hpp"
82 #include "runtime/orderAccess.inline.hpp"
83 #include "runtime/vmThread.hpp"
84 #include "utilities/align.hpp"
85 #include "utilities/globalDefinitions.hpp"
86 #include "utilities/stack.inline.hpp"
87
88 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
89
90 // INVARIANTS/NOTES
91 //
92 // All allocation activity covered by the G1CollectedHeap interface is
93 // serialized by acquiring the HeapLock. This happens in mem_allocate
94 // and allocate_new_tlab, which are the "entry" points to the
95 // allocation code from the rest of the JVM. (Note that this does not
96 // apply to TLAB allocation, which is not part of this interface: it
97 // is done by clients of this interface.)
98
99 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
100 private:
101 size_t _num_dirtied;
102 G1CollectedHeap* _g1h;
103 G1SATBCardTableLoggingModRefBS* _g1_bs;
104
105 HeapRegion* region_for_card(jbyte* card_ptr) const {
106 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
107 }
108
109 bool will_become_free(HeapRegion* hr) const {
110 // A region will be freed by free_collection_set if the region is in the
111 // collection set and has not had an evacuation failure.
112 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
113 }
114
115 public:
116 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
117 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
118
119 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
120 HeapRegion* hr = region_for_card(card_ptr);
121
122 // Should only dirty cards in regions that won't be freed.
123 if (!will_become_free(hr)) {
124 *card_ptr = CardTableModRefBS::dirty_card_val();
125 _num_dirtied++;
126 }
127
128 return true;
129 }
130
131 size_t num_dirtied() const { return _num_dirtied; }
132 };
133
134
135 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
136 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
137 }
138
139 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
140 // The from card cache is not the memory that is actually committed. So we cannot
141 // take advantage of the zero_filled parameter.
142 reset_from_card_cache(start_idx, num_regions);
143 }
144
145 // Returns true if the reference points to an object that
146 // can move in an incremental collection.
147 bool G1CollectedHeap::is_scavengable(const void* p) {
148 HeapRegion* hr = heap_region_containing(p);
149 return !hr->is_pinned();
150 }
151
152 // Private methods.
153
154 HeapRegion*
155 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
156 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
157 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
158 if (!_secondary_free_list.is_empty()) {
159 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
160 "secondary_free_list has %u entries",
161 _secondary_free_list.length());
162 // It looks as if there are free regions available on the
163 // secondary_free_list. Let's move them to the free_list and try
164 // again to allocate from it.
165 append_secondary_free_list();
166
167 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
168 "empty we should have moved at least one entry to the free_list");
169 HeapRegion* res = _hrm.allocate_free_region(is_old);
170 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
171 "allocated " HR_FORMAT " from secondary_free_list",
172 HR_FORMAT_PARAMS(res));
173 return res;
174 }
175
176 // Wait here until we get notified either when (a) there are no
177 // more free regions coming or (b) some regions have been moved on
178 // the secondary_free_list.
179 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
180 }
181
182 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
183 "could not allocate from secondary_free_list");
184 return NULL;
185 }
186
187 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
188 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
189 "the only time we use this to allocate a humongous region is "
190 "when we are allocating a single humongous region");
191
192 HeapRegion* res;
193 if (G1StressConcRegionFreeing) {
194 if (!_secondary_free_list.is_empty()) {
195 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
196 "forced to look at the secondary_free_list");
197 res = new_region_try_secondary_free_list(is_old);
198 if (res != NULL) {
199 return res;
200 }
201 }
202 }
203
204 res = _hrm.allocate_free_region(is_old);
205
206 if (res == NULL) {
207 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
208 "res == NULL, trying the secondary_free_list");
209 res = new_region_try_secondary_free_list(is_old);
210 }
211 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
212 // Currently, only attempts to allocate GC alloc regions set
213 // do_expand to true. So, we should only reach here during a
214 // safepoint. If this assumption changes we might have to
215 // reconsider the use of _expand_heap_after_alloc_failure.
216 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
217
218 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
219 word_size * HeapWordSize);
220
221 if (expand(word_size * HeapWordSize)) {
222 // Given that expand() succeeded in expanding the heap, and we
223 // always expand the heap by an amount aligned to the heap
224 // region size, the free list should in theory not be empty.
225 // In either case allocate_free_region() will check for NULL.
226 res = _hrm.allocate_free_region(is_old);
227 } else {
228 _expand_heap_after_alloc_failure = false;
229 }
230 }
231 return res;
232 }
233
234 HeapWord*
235 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
236 uint num_regions,
237 size_t word_size,
238 AllocationContext_t context) {
239 assert(first != G1_NO_HRM_INDEX, "pre-condition");
240 assert(is_humongous(word_size), "word_size should be humongous");
241 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
242
243 // Index of last region in the series.
244 uint last = first + num_regions - 1;
245
246 // We need to initialize the region(s) we just discovered. This is
247 // a bit tricky given that it can happen concurrently with
248 // refinement threads refining cards on these regions and
249 // potentially wanting to refine the BOT as they are scanning
250 // those cards (this can happen shortly after a cleanup; see CR
251 // 6991377). So we have to set up the region(s) carefully and in
252 // a specific order.
253
254 // The word size sum of all the regions we will allocate.
255 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
256 assert(word_size <= word_size_sum, "sanity");
257
258 // This will be the "starts humongous" region.
259 HeapRegion* first_hr = region_at(first);
260 // The header of the new object will be placed at the bottom of
261 // the first region.
262 HeapWord* new_obj = first_hr->bottom();
263 // This will be the new top of the new object.
264 HeapWord* obj_top = new_obj + word_size;
265
266 // First, we need to zero the header of the space that we will be
267 // allocating. When we update top further down, some refinement
268 // threads might try to scan the region. By zeroing the header we
269 // ensure that any thread that will try to scan the region will
270 // come across the zero klass word and bail out.
271 //
272 // NOTE: It would not have been correct to have used
273 // CollectedHeap::fill_with_object() and make the space look like
274 // an int array. The thread that is doing the allocation will
275 // later update the object header to a potentially different array
276 // type and, for a very short period of time, the klass and length
277 // fields will be inconsistent. This could cause a refinement
278 // thread to calculate the object size incorrectly.
279 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
280
281 // Next, pad out the unused tail of the last region with filler
282 // objects, for improved usage accounting.
283 // How many words we use for filler objects.
284 size_t word_fill_size = word_size_sum - word_size;
285
286 // How many words memory we "waste" which cannot hold a filler object.
287 size_t words_not_fillable = 0;
288
289 if (word_fill_size >= min_fill_size()) {
290 fill_with_objects(obj_top, word_fill_size);
291 } else if (word_fill_size > 0) {
292 // We have space to fill, but we cannot fit an object there.
293 words_not_fillable = word_fill_size;
294 word_fill_size = 0;
295 }
296
297 // We will set up the first region as "starts humongous". This
298 // will also update the BOT covering all the regions to reflect
299 // that there is a single object that starts at the bottom of the
300 // first region.
301 first_hr->set_starts_humongous(obj_top, word_fill_size);
302 first_hr->set_allocation_context(context);
303 // Then, if there are any, we will set up the "continues
304 // humongous" regions.
305 HeapRegion* hr = NULL;
306 for (uint i = first + 1; i <= last; ++i) {
307 hr = region_at(i);
308 hr->set_continues_humongous(first_hr);
309 hr->set_allocation_context(context);
310 }
311
312 // Up to this point no concurrent thread would have been able to
313 // do any scanning on any region in this series. All the top
314 // fields still point to bottom, so the intersection between
315 // [bottom,top] and [card_start,card_end] will be empty. Before we
316 // update the top fields, we'll do a storestore to make sure that
317 // no thread sees the update to top before the zeroing of the
318 // object header and the BOT initialization.
319 OrderAccess::storestore();
320
321 // Now, we will update the top fields of the "continues humongous"
322 // regions except the last one.
323 for (uint i = first; i < last; ++i) {
324 hr = region_at(i);
325 hr->set_top(hr->end());
326 }
327
328 hr = region_at(last);
329 // If we cannot fit a filler object, we must set top to the end
330 // of the humongous object, otherwise we cannot iterate the heap
331 // and the BOT will not be complete.
332 hr->set_top(hr->end() - words_not_fillable);
333
334 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
335 "obj_top should be in last region");
336
337 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
338
339 assert(words_not_fillable == 0 ||
340 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
341 "Miscalculation in humongous allocation");
342
343 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
344
345 for (uint i = first; i <= last; ++i) {
346 hr = region_at(i);
347 _humongous_set.add(hr);
348 _hr_printer.alloc(hr);
349 }
350
351 return new_obj;
352 }
353
354 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
355 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
356 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
357 }
358
359 // If could fit into free regions w/o expansion, try.
360 // Otherwise, if can expand, do so.
361 // Otherwise, if using ex regions might help, try with ex given back.
362 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
363 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
364
365 _verifier->verify_region_sets_optional();
366
367 uint first = G1_NO_HRM_INDEX;
368 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
369
370 if (obj_regions == 1) {
371 // Only one region to allocate, try to use a fast path by directly allocating
372 // from the free lists. Do not try to expand here, we will potentially do that
373 // later.
374 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
375 if (hr != NULL) {
376 first = hr->hrm_index();
377 }
378 } else {
379 // We can't allocate humongous regions spanning more than one region while
380 // cleanupComplete() is running, since some of the regions we find to be
381 // empty might not yet be added to the free list. It is not straightforward
382 // to know in which list they are on so that we can remove them. We only
383 // need to do this if we need to allocate more than one region to satisfy the
384 // current humongous allocation request. If we are only allocating one region
385 // we use the one-region region allocation code (see above), that already
386 // potentially waits for regions from the secondary free list.
387 wait_while_free_regions_coming();
388 append_secondary_free_list_if_not_empty_with_lock();
389
390 // Policy: Try only empty regions (i.e. already committed first). Maybe we
391 // are lucky enough to find some.
392 first = _hrm.find_contiguous_only_empty(obj_regions);
393 if (first != G1_NO_HRM_INDEX) {
394 _hrm.allocate_free_regions_starting_at(first, obj_regions);
395 }
396 }
397
398 if (first == G1_NO_HRM_INDEX) {
399 // Policy: We could not find enough regions for the humongous object in the
400 // free list. Look through the heap to find a mix of free and uncommitted regions.
401 // If so, try expansion.
402 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
403 if (first != G1_NO_HRM_INDEX) {
404 // We found something. Make sure these regions are committed, i.e. expand
405 // the heap. Alternatively we could do a defragmentation GC.
406 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
407 word_size * HeapWordSize);
408
409 _hrm.expand_at(first, obj_regions, workers());
410 g1_policy()->record_new_heap_size(num_regions());
411
412 #ifdef ASSERT
413 for (uint i = first; i < first + obj_regions; ++i) {
414 HeapRegion* hr = region_at(i);
415 assert(hr->is_free(), "sanity");
416 assert(hr->is_empty(), "sanity");
417 assert(is_on_master_free_list(hr), "sanity");
418 }
419 #endif
420 _hrm.allocate_free_regions_starting_at(first, obj_regions);
421 } else {
422 // Policy: Potentially trigger a defragmentation GC.
423 }
424 }
425
426 HeapWord* result = NULL;
427 if (first != G1_NO_HRM_INDEX) {
428 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
429 word_size, context);
430 assert(result != NULL, "it should always return a valid result");
431
432 // A successful humongous object allocation changes the used space
433 // information of the old generation so we need to recalculate the
434 // sizes and update the jstat counters here.
435 g1mm()->update_sizes();
436 }
437
438 _verifier->verify_region_sets_optional();
439
440 return result;
441 }
442
443 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
444 assert_heap_not_locked_and_not_at_safepoint();
445 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
446
447 uint dummy_gc_count_before;
448 uint dummy_gclocker_retry_count = 0;
449 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
450 }
451
452 HeapWord*
453 G1CollectedHeap::mem_allocate(size_t word_size,
454 bool* gc_overhead_limit_was_exceeded) {
455 assert_heap_not_locked_and_not_at_safepoint();
456
457 // Loop until the allocation is satisfied, or unsatisfied after GC.
458 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
459 uint gc_count_before;
460
461 HeapWord* result = NULL;
462 if (!is_humongous(word_size)) {
463 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
464 } else {
465 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
466 }
467 if (result != NULL) {
468 return result;
469 }
470
471 // Create the garbage collection operation...
472 VM_G1CollectForAllocation op(gc_count_before, word_size);
473 op.set_allocation_context(AllocationContext::current());
474
475 // ...and get the VM thread to execute it.
476 VMThread::execute(&op);
477
478 if (op.prologue_succeeded() && op.pause_succeeded()) {
479 // If the operation was successful we'll return the result even
480 // if it is NULL. If the allocation attempt failed immediately
481 // after a Full GC, it's unlikely we'll be able to allocate now.
482 HeapWord* result = op.result();
483 if (result != NULL && !is_humongous(word_size)) {
484 // Allocations that take place on VM operations do not do any
485 // card dirtying and we have to do it here. We only have to do
486 // this for non-humongous allocations, though.
487 dirty_young_block(result, word_size);
488 }
489 return result;
490 } else {
491 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
492 return NULL;
493 }
494 assert(op.result() == NULL,
495 "the result should be NULL if the VM op did not succeed");
496 }
497
498 // Give a warning if we seem to be looping forever.
499 if ((QueuedAllocationWarningCount > 0) &&
500 (try_count % QueuedAllocationWarningCount == 0)) {
501 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
502 }
503 }
504
505 ShouldNotReachHere();
506 return NULL;
507 }
508
509 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
510 AllocationContext_t context,
511 uint* gc_count_before_ret,
512 uint* gclocker_retry_count_ret) {
513 // Make sure you read the note in attempt_allocation_humongous().
514
515 assert_heap_not_locked_and_not_at_safepoint();
516 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
517 "be called for humongous allocation requests");
518
519 // We should only get here after the first-level allocation attempt
520 // (attempt_allocation()) failed to allocate.
521
522 // We will loop until a) we manage to successfully perform the
523 // allocation or b) we successfully schedule a collection which
524 // fails to perform the allocation. b) is the only case when we'll
525 // return NULL.
526 HeapWord* result = NULL;
527 for (int try_count = 1; /* we'll return */; try_count += 1) {
528 bool should_try_gc;
529 uint gc_count_before;
530
531 {
532 MutexLockerEx x(Heap_lock);
533 result = _allocator->attempt_allocation_locked(word_size, context);
534 if (result != NULL) {
535 return result;
536 }
537
538 if (GCLocker::is_active_and_needs_gc()) {
539 if (g1_policy()->can_expand_young_list()) {
540 // No need for an ergo verbose message here,
541 // can_expand_young_list() does this when it returns true.
542 result = _allocator->attempt_allocation_force(word_size, context);
543 if (result != NULL) {
544 return result;
545 }
546 }
547 should_try_gc = false;
548 } else {
549 // The GCLocker may not be active but the GCLocker initiated
550 // GC may not yet have been performed (GCLocker::needs_gc()
551 // returns true). In this case we do not try this GC and
552 // wait until the GCLocker initiated GC is performed, and
553 // then retry the allocation.
554 if (GCLocker::needs_gc()) {
555 should_try_gc = false;
556 } else {
557 // Read the GC count while still holding the Heap_lock.
558 gc_count_before = total_collections();
559 should_try_gc = true;
560 }
561 }
562 }
563
564 if (should_try_gc) {
565 bool succeeded;
566 result = do_collection_pause(word_size, gc_count_before, &succeeded,
567 GCCause::_g1_inc_collection_pause);
568 if (result != NULL) {
569 assert(succeeded, "only way to get back a non-NULL result");
570 return result;
571 }
572
573 if (succeeded) {
574 // If we get here we successfully scheduled a collection which
575 // failed to allocate. No point in trying to allocate
576 // further. We'll just return NULL.
577 MutexLockerEx x(Heap_lock);
578 *gc_count_before_ret = total_collections();
579 return NULL;
580 }
581 } else {
582 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
583 MutexLockerEx x(Heap_lock);
584 *gc_count_before_ret = total_collections();
585 return NULL;
586 }
587 // The GCLocker is either active or the GCLocker initiated
588 // GC has not yet been performed. Stall until it is and
589 // then retry the allocation.
590 GCLocker::stall_until_clear();
591 (*gclocker_retry_count_ret) += 1;
592 }
593
594 // We can reach here if we were unsuccessful in scheduling a
595 // collection (because another thread beat us to it) or if we were
596 // stalled due to the GC locker. In either can we should retry the
597 // allocation attempt in case another thread successfully
598 // performed a collection and reclaimed enough space. We do the
599 // first attempt (without holding the Heap_lock) here and the
600 // follow-on attempt will be at the start of the next loop
601 // iteration (after taking the Heap_lock).
602 result = _allocator->attempt_allocation(word_size, context);
603 if (result != NULL) {
604 return result;
605 }
606
607 // Give a warning if we seem to be looping forever.
608 if ((QueuedAllocationWarningCount > 0) &&
609 (try_count % QueuedAllocationWarningCount == 0)) {
610 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
611 "retries %d times", try_count);
612 }
613 }
614
615 ShouldNotReachHere();
616 return NULL;
617 }
618
619 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
620 assert_at_safepoint(true /* should_be_vm_thread */);
621 if (_archive_allocator == NULL) {
622 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
623 }
624 }
625
626 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
627 // Allocations in archive regions cannot be of a size that would be considered
628 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
629 // may be different at archive-restore time.
630 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
631 }
632
633 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
634 assert_at_safepoint(true /* should_be_vm_thread */);
635 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
636 if (is_archive_alloc_too_large(word_size)) {
637 return NULL;
638 }
639 return _archive_allocator->archive_mem_allocate(word_size);
640 }
641
642 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
643 size_t end_alignment_in_bytes) {
644 assert_at_safepoint(true /* should_be_vm_thread */);
645 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
646
647 // Call complete_archive to do the real work, filling in the MemRegion
648 // array with the archive regions.
649 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
650 delete _archive_allocator;
651 _archive_allocator = NULL;
652 }
653
654 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
655 assert(ranges != NULL, "MemRegion array NULL");
656 assert(count != 0, "No MemRegions provided");
657 MemRegion reserved = _hrm.reserved();
658 for (size_t i = 0; i < count; i++) {
659 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
660 return false;
661 }
662 }
663 return true;
664 }
665
666 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
667 size_t count,
668 bool open) {
669 assert(!is_init_completed(), "Expect to be called at JVM init time");
670 assert(ranges != NULL, "MemRegion array NULL");
671 assert(count != 0, "No MemRegions provided");
672 MutexLockerEx x(Heap_lock);
673
674 MemRegion reserved = _hrm.reserved();
675 HeapWord* prev_last_addr = NULL;
676 HeapRegion* prev_last_region = NULL;
677
678 // Temporarily disable pretouching of heap pages. This interface is used
679 // when mmap'ing archived heap data in, so pre-touching is wasted.
680 FlagSetting fs(AlwaysPreTouch, false);
681
682 // Enable archive object checking used by G1MarkSweep. We have to let it know
683 // about each archive range, so that objects in those ranges aren't marked.
684 G1ArchiveAllocator::enable_archive_object_check();
685
686 // For each specified MemRegion range, allocate the corresponding G1
687 // regions and mark them as archive regions. We expect the ranges
688 // in ascending starting address order, without overlap.
689 for (size_t i = 0; i < count; i++) {
690 MemRegion curr_range = ranges[i];
691 HeapWord* start_address = curr_range.start();
692 size_t word_size = curr_range.word_size();
693 HeapWord* last_address = curr_range.last();
694 size_t commits = 0;
695
696 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
697 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
698 p2i(start_address), p2i(last_address));
699 guarantee(start_address > prev_last_addr,
700 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
701 p2i(start_address), p2i(prev_last_addr));
702 prev_last_addr = last_address;
703
704 // Check for ranges that start in the same G1 region in which the previous
705 // range ended, and adjust the start address so we don't try to allocate
706 // the same region again. If the current range is entirely within that
707 // region, skip it, just adjusting the recorded top.
708 HeapRegion* start_region = _hrm.addr_to_region(start_address);
709 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
710 start_address = start_region->end();
711 if (start_address > last_address) {
712 increase_used(word_size * HeapWordSize);
713 start_region->set_top(last_address + 1);
714 continue;
715 }
716 start_region->set_top(start_address);
717 curr_range = MemRegion(start_address, last_address + 1);
718 start_region = _hrm.addr_to_region(start_address);
719 }
720
721 // Perform the actual region allocation, exiting if it fails.
722 // Then note how much new space we have allocated.
723 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
724 return false;
725 }
726 increase_used(word_size * HeapWordSize);
727 if (commits != 0) {
728 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
729 HeapRegion::GrainWords * HeapWordSize * commits);
730
731 }
732
733 // Mark each G1 region touched by the range as archive, add it to
734 // the old set, and set the allocation context and top.
735 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
736 HeapRegion* last_region = _hrm.addr_to_region(last_address);
737 prev_last_region = last_region;
738
739 while (curr_region != NULL) {
740 assert(curr_region->is_empty() && !curr_region->is_pinned(),
741 "Region already in use (index %u)", curr_region->hrm_index());
742 curr_region->set_allocation_context(AllocationContext::system());
743 if (open) {
744 curr_region->set_open_archive();
745 } else {
746 curr_region->set_closed_archive();
747 }
748 _hr_printer.alloc(curr_region);
749 _old_set.add(curr_region);
750 HeapWord* top;
751 HeapRegion* next_region;
752 if (curr_region != last_region) {
753 top = curr_region->end();
754 next_region = _hrm.next_region_in_heap(curr_region);
755 } else {
756 top = last_address + 1;
757 next_region = NULL;
758 }
759 curr_region->set_top(top);
760 curr_region->set_first_dead(top);
761 curr_region->set_end_of_live(top);
762 curr_region = next_region;
763 }
764
765 // Notify mark-sweep of the archive
766 G1ArchiveAllocator::set_range_archive(curr_range, open);
767 }
768 return true;
769 }
770
771 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
772 assert(!is_init_completed(), "Expect to be called at JVM init time");
773 assert(ranges != NULL, "MemRegion array NULL");
774 assert(count != 0, "No MemRegions provided");
775 MemRegion reserved = _hrm.reserved();
776 HeapWord *prev_last_addr = NULL;
777 HeapRegion* prev_last_region = NULL;
778
779 // For each MemRegion, create filler objects, if needed, in the G1 regions
780 // that contain the address range. The address range actually within the
781 // MemRegion will not be modified. That is assumed to have been initialized
782 // elsewhere, probably via an mmap of archived heap data.
783 MutexLockerEx x(Heap_lock);
784 for (size_t i = 0; i < count; i++) {
785 HeapWord* start_address = ranges[i].start();
786 HeapWord* last_address = ranges[i].last();
787
788 assert(reserved.contains(start_address) && reserved.contains(last_address),
789 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
790 p2i(start_address), p2i(last_address));
791 assert(start_address > prev_last_addr,
792 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
793 p2i(start_address), p2i(prev_last_addr));
794
795 HeapRegion* start_region = _hrm.addr_to_region(start_address);
796 HeapRegion* last_region = _hrm.addr_to_region(last_address);
797 HeapWord* bottom_address = start_region->bottom();
798
799 // Check for a range beginning in the same region in which the
800 // previous one ended.
801 if (start_region == prev_last_region) {
802 bottom_address = prev_last_addr + 1;
803 }
804
805 // Verify that the regions were all marked as archive regions by
806 // alloc_archive_regions.
807 HeapRegion* curr_region = start_region;
808 while (curr_region != NULL) {
809 guarantee(curr_region->is_archive(),
810 "Expected archive region at index %u", curr_region->hrm_index());
811 if (curr_region != last_region) {
812 curr_region = _hrm.next_region_in_heap(curr_region);
813 } else {
814 curr_region = NULL;
815 }
816 }
817
818 prev_last_addr = last_address;
819 prev_last_region = last_region;
820
821 // Fill the memory below the allocated range with dummy object(s),
822 // if the region bottom does not match the range start, or if the previous
823 // range ended within the same G1 region, and there is a gap.
824 if (start_address != bottom_address) {
825 size_t fill_size = pointer_delta(start_address, bottom_address);
826 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
827 increase_used(fill_size * HeapWordSize);
828 }
829 }
830 }
831
832 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
833 uint* gc_count_before_ret,
834 uint* gclocker_retry_count_ret) {
835 assert_heap_not_locked_and_not_at_safepoint();
836 assert(!is_humongous(word_size), "attempt_allocation() should not "
837 "be called for humongous allocation requests");
838
839 AllocationContext_t context = AllocationContext::current();
840 HeapWord* result = _allocator->attempt_allocation(word_size, context);
841
842 if (result == NULL) {
843 result = attempt_allocation_slow(word_size,
844 context,
845 gc_count_before_ret,
846 gclocker_retry_count_ret);
847 }
848 assert_heap_not_locked();
849 if (result != NULL) {
850 dirty_young_block(result, word_size);
851 }
852 return result;
853 }
854
855 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
856 assert(!is_init_completed(), "Expect to be called at JVM init time");
857 assert(ranges != NULL, "MemRegion array NULL");
858 assert(count != 0, "No MemRegions provided");
859 MemRegion reserved = _hrm.reserved();
860 HeapWord* prev_last_addr = NULL;
861 HeapRegion* prev_last_region = NULL;
862 size_t size_used = 0;
863 size_t uncommitted_regions = 0;
864
865 // For each Memregion, free the G1 regions that constitute it, and
866 // notify mark-sweep that the range is no longer to be considered 'archive.'
867 MutexLockerEx x(Heap_lock);
868 for (size_t i = 0; i < count; i++) {
869 HeapWord* start_address = ranges[i].start();
870 HeapWord* last_address = ranges[i].last();
871
872 assert(reserved.contains(start_address) && reserved.contains(last_address),
873 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
874 p2i(start_address), p2i(last_address));
875 assert(start_address > prev_last_addr,
876 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
877 p2i(start_address), p2i(prev_last_addr));
878 size_used += ranges[i].byte_size();
879 prev_last_addr = last_address;
880
881 HeapRegion* start_region = _hrm.addr_to_region(start_address);
882 HeapRegion* last_region = _hrm.addr_to_region(last_address);
883
884 // Check for ranges that start in the same G1 region in which the previous
885 // range ended, and adjust the start address so we don't try to free
886 // the same region again. If the current range is entirely within that
887 // region, skip it.
888 if (start_region == prev_last_region) {
889 start_address = start_region->end();
890 if (start_address > last_address) {
891 continue;
892 }
893 start_region = _hrm.addr_to_region(start_address);
894 }
895 prev_last_region = last_region;
896
897 // After verifying that each region was marked as an archive region by
898 // alloc_archive_regions, set it free and empty and uncommit it.
899 HeapRegion* curr_region = start_region;
900 while (curr_region != NULL) {
901 guarantee(curr_region->is_archive(),
902 "Expected archive region at index %u", curr_region->hrm_index());
903 uint curr_index = curr_region->hrm_index();
904 _old_set.remove(curr_region);
905 curr_region->set_free();
906 curr_region->set_top(curr_region->bottom());
907 if (curr_region != last_region) {
908 curr_region = _hrm.next_region_in_heap(curr_region);
909 } else {
910 curr_region = NULL;
911 }
912 _hrm.shrink_at(curr_index, 1);
913 uncommitted_regions++;
914 }
915
916 // Notify mark-sweep that this is no longer an archive range.
917 G1ArchiveAllocator::set_range_archive(ranges[i], false);
918 }
919
920 if (uncommitted_regions != 0) {
921 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
922 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
923 }
924 decrease_used(size_used);
925 }
926
927 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
928 uint* gc_count_before_ret,
929 uint* gclocker_retry_count_ret) {
930 // The structure of this method has a lot of similarities to
931 // attempt_allocation_slow(). The reason these two were not merged
932 // into a single one is that such a method would require several "if
933 // allocation is not humongous do this, otherwise do that"
934 // conditional paths which would obscure its flow. In fact, an early
935 // version of this code did use a unified method which was harder to
936 // follow and, as a result, it had subtle bugs that were hard to
937 // track down. So keeping these two methods separate allows each to
938 // be more readable. It will be good to keep these two in sync as
939 // much as possible.
940
941 assert_heap_not_locked_and_not_at_safepoint();
942 assert(is_humongous(word_size), "attempt_allocation_humongous() "
943 "should only be called for humongous allocations");
944
945 // Humongous objects can exhaust the heap quickly, so we should check if we
946 // need to start a marking cycle at each humongous object allocation. We do
947 // the check before we do the actual allocation. The reason for doing it
948 // before the allocation is that we avoid having to keep track of the newly
949 // allocated memory while we do a GC.
950 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
951 word_size)) {
952 collect(GCCause::_g1_humongous_allocation);
953 }
954
955 // We will loop until a) we manage to successfully perform the
956 // allocation or b) we successfully schedule a collection which
957 // fails to perform the allocation. b) is the only case when we'll
958 // return NULL.
959 HeapWord* result = NULL;
960 for (int try_count = 1; /* we'll return */; try_count += 1) {
961 bool should_try_gc;
962 uint gc_count_before;
963
964 {
965 MutexLockerEx x(Heap_lock);
966
967 // Given that humongous objects are not allocated in young
968 // regions, we'll first try to do the allocation without doing a
969 // collection hoping that there's enough space in the heap.
970 result = humongous_obj_allocate(word_size, AllocationContext::current());
971 if (result != NULL) {
972 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
973 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
974 return result;
975 }
976
977 if (GCLocker::is_active_and_needs_gc()) {
978 should_try_gc = false;
979 } else {
980 // The GCLocker may not be active but the GCLocker initiated
981 // GC may not yet have been performed (GCLocker::needs_gc()
982 // returns true). In this case we do not try this GC and
983 // wait until the GCLocker initiated GC is performed, and
984 // then retry the allocation.
985 if (GCLocker::needs_gc()) {
986 should_try_gc = false;
987 } else {
988 // Read the GC count while still holding the Heap_lock.
989 gc_count_before = total_collections();
990 should_try_gc = true;
991 }
992 }
993 }
994
995 if (should_try_gc) {
996 // If we failed to allocate the humongous object, we should try to
997 // do a collection pause (if we're allowed) in case it reclaims
998 // enough space for the allocation to succeed after the pause.
999
1000 bool succeeded;
1001 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1002 GCCause::_g1_humongous_allocation);
1003 if (result != NULL) {
1004 assert(succeeded, "only way to get back a non-NULL result");
1005 return result;
1006 }
1007
1008 if (succeeded) {
1009 // If we get here we successfully scheduled a collection which
1010 // failed to allocate. No point in trying to allocate
1011 // further. We'll just return NULL.
1012 MutexLockerEx x(Heap_lock);
1013 *gc_count_before_ret = total_collections();
1014 return NULL;
1015 }
1016 } else {
1017 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1018 MutexLockerEx x(Heap_lock);
1019 *gc_count_before_ret = total_collections();
1020 return NULL;
1021 }
1022 // The GCLocker is either active or the GCLocker initiated
1023 // GC has not yet been performed. Stall until it is and
1024 // then retry the allocation.
1025 GCLocker::stall_until_clear();
1026 (*gclocker_retry_count_ret) += 1;
1027 }
1028
1029 // We can reach here if we were unsuccessful in scheduling a
1030 // collection (because another thread beat us to it) or if we were
1031 // stalled due to the GC locker. In either can we should retry the
1032 // allocation attempt in case another thread successfully
1033 // performed a collection and reclaimed enough space. Give a
1034 // warning if we seem to be looping forever.
1035
1036 if ((QueuedAllocationWarningCount > 0) &&
1037 (try_count % QueuedAllocationWarningCount == 0)) {
1038 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1039 "retries %d times", try_count);
1040 }
1041 }
1042
1043 ShouldNotReachHere();
1044 return NULL;
1045 }
1046
1047 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1048 AllocationContext_t context,
1049 bool expect_null_mutator_alloc_region) {
1050 assert_at_safepoint(true /* should_be_vm_thread */);
1051 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1052 "the current alloc region was unexpectedly found to be non-NULL");
1053
1054 if (!is_humongous(word_size)) {
1055 return _allocator->attempt_allocation_locked(word_size, context);
1056 } else {
1057 HeapWord* result = humongous_obj_allocate(word_size, context);
1058 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1059 collector_state()->set_initiate_conc_mark_if_possible(true);
1060 }
1061 return result;
1062 }
1063
1064 ShouldNotReachHere();
1065 }
1066
1067 class PostCompactionPrinterClosure: public HeapRegionClosure {
1068 private:
1069 G1HRPrinter* _hr_printer;
1070 public:
1071 bool doHeapRegion(HeapRegion* hr) {
1072 assert(!hr->is_young(), "not expecting to find young regions");
1073 _hr_printer->post_compaction(hr);
1074 return false;
1075 }
1076
1077 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1078 : _hr_printer(hr_printer) { }
1079 };
1080
1081 void G1CollectedHeap::print_hrm_post_compaction() {
1082 if (_hr_printer.is_active()) {
1083 PostCompactionPrinterClosure cl(hr_printer());
1084 heap_region_iterate(&cl);
1085 }
1086
1087 }
1088
1089 void G1CollectedHeap::abort_concurrent_cycle() {
1090 // Note: When we have a more flexible GC logging framework that
1091 // allows us to add optional attributes to a GC log record we
1092 // could consider timing and reporting how long we wait in the
1093 // following two methods.
1094 wait_while_free_regions_coming();
1095 // If we start the compaction before the CM threads finish
1096 // scanning the root regions we might trip them over as we'll
1097 // be moving objects / updating references. So let's wait until
1098 // they are done. By telling them to abort, they should complete
1099 // early.
1100 _cm->root_regions()->abort();
1101 _cm->root_regions()->wait_until_scan_finished();
1102 append_secondary_free_list_if_not_empty_with_lock();
1103
1104 // Disable discovery and empty the discovered lists
1105 // for the CM ref processor.
1106 ref_processor_cm()->disable_discovery();
1107 ref_processor_cm()->abandon_partial_discovery();
1108 ref_processor_cm()->verify_no_references_recorded();
1109
1110 // Abandon current iterations of concurrent marking and concurrent
1111 // refinement, if any are in progress.
1112 concurrent_mark()->abort();
1113 }
1114
1115 void G1CollectedHeap::prepare_heap_for_full_collection() {
1116 // Make sure we'll choose a new allocation region afterwards.
1117 _allocator->release_mutator_alloc_region();
1118 _allocator->abandon_gc_alloc_regions();
1119 g1_rem_set()->cleanupHRRS();
1120
1121 // We may have added regions to the current incremental collection
1122 // set between the last GC or pause and now. We need to clear the
1123 // incremental collection set and then start rebuilding it afresh
1124 // after this full GC.
1125 abandon_collection_set(collection_set());
1126
1127 tear_down_region_sets(false /* free_list_only */);
1128 collector_state()->set_gcs_are_young(true);
1129 }
1130
1131 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1132 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1133 assert(used() == recalculate_used(), "Should be equal");
1134 _verifier->verify_region_sets_optional();
1135 _verifier->verify_before_gc();
1136 _verifier->check_bitmaps("Full GC Start");
1137 }
1138
1139 void G1CollectedHeap::prepare_heap_for_mutators() {
1140 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1141 ClassLoaderDataGraph::purge();
1142 MetaspaceAux::verify_metrics();
1143
1144 // Prepare heap for normal collections.
1145 assert(num_free_regions() == 0, "we should not have added any free regions");
1146 rebuild_region_sets(false /* free_list_only */);
1147 abort_refinement();
1148 resize_if_necessary_after_full_collection();
1149
1150 // Rebuild the strong code root lists for each region
1151 rebuild_strong_code_roots();
1152
1153 // Start a new incremental collection set for the next pause
1154 start_new_collection_set();
1155
1156 _allocator->init_mutator_alloc_region();
1157
1158 // Post collection state updates.
1159 MetaspaceGC::compute_new_size();
1160 }
1161
1162 void G1CollectedHeap::abort_refinement() {
1163 if (_hot_card_cache->use_cache()) {
1164 _hot_card_cache->reset_card_counts();
1165 _hot_card_cache->reset_hot_cache();
1166 }
1167
1168 // Discard all remembered set updates.
1169 JavaThread::dirty_card_queue_set().abandon_logs();
1170 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1171 }
1172
1173 void G1CollectedHeap::verify_after_full_collection() {
1174 check_gc_time_stamps();
1175 _hrm.verify_optional();
1176 _verifier->verify_region_sets_optional();
1177 _verifier->verify_after_gc();
1178 // Clear the previous marking bitmap, if needed for bitmap verification.
1179 // Note we cannot do this when we clear the next marking bitmap in
1180 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1181 // objects marked during a full GC against the previous bitmap.
1182 // But we need to clear it before calling check_bitmaps below since
1183 // the full GC has compacted objects and updated TAMS but not updated
1184 // the prev bitmap.
1185 if (G1VerifyBitmaps) {
1186 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1187 _cm->clear_prev_bitmap(workers());
1188 }
1189 _verifier->check_bitmaps("Full GC End");
1190
1191 // At this point there should be no regions in the
1192 // entire heap tagged as young.
1193 assert(check_young_list_empty(), "young list should be empty at this point");
1194
1195 // Note: since we've just done a full GC, concurrent
1196 // marking is no longer active. Therefore we need not
1197 // re-enable reference discovery for the CM ref processor.
1198 // That will be done at the start of the next marking cycle.
1199 // We also know that the STW processor should no longer
1200 // discover any new references.
1201 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1202 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1203 ref_processor_stw()->verify_no_references_recorded();
1204 ref_processor_cm()->verify_no_references_recorded();
1205 }
1206
1207 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1208 print_hrm_post_compaction();
1209 heap_transition->print();
1210 print_heap_after_gc();
1211 print_heap_regions();
1212 #ifdef TRACESPINNING
1213 ParallelTaskTerminator::print_termination_counts();
1214 #endif
1215 }
1216
1217 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1218 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1219 g1_policy()->record_full_collection_start();
1220
1221 print_heap_before_gc();
1222 print_heap_regions();
1223
1224 abort_concurrent_cycle();
1225 verify_before_full_collection(scope->is_explicit_gc());
1226
1227 gc_prologue(true);
1228 prepare_heap_for_full_collection();
1229
1230 G1SerialFullCollector serial(scope, ref_processor_stw());
1231 serial.prepare_collection();
1232 serial.collect();
1233 serial.complete_collection();
1234
1235 prepare_heap_for_mutators();
1236
1237 g1_policy()->record_full_collection_end();
1238 gc_epilogue(true);
1239
1240 // Post collection verification.
1241 verify_after_full_collection();
1242
1243 // Post collection logging.
1244 // We should do this after we potentially resize the heap so
1245 // that all the COMMIT / UNCOMMIT events are generated before
1246 // the compaction events.
1247 print_heap_after_full_collection(scope->heap_transition());
1248 }
1249
1250 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1251 bool clear_all_soft_refs) {
1252 assert_at_safepoint(true /* should_be_vm_thread */);
1253
1254 if (GCLocker::check_active_before_gc()) {
1255 // Full GC was not completed.
1256 return false;
1257 }
1258
1259 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1260 collector_policy()->should_clear_all_soft_refs();
1261
1262 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1263 do_full_collection_inner(&scope);
1264
1265 // Full collection was successfully completed.
1266 return true;
1267 }
1268
1269 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1270 // Currently, there is no facility in the do_full_collection(bool) API to notify
1271 // the caller that the collection did not succeed (e.g., because it was locked
1272 // out by the GC locker). So, right now, we'll ignore the return value.
1273 bool dummy = do_full_collection(true, /* explicit_gc */
1274 clear_all_soft_refs);
1275 }
1276
1277 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1278 // Include bytes that will be pre-allocated to support collections, as "used".
1279 const size_t used_after_gc = used();
1280 const size_t capacity_after_gc = capacity();
1281 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1282
1283 // This is enforced in arguments.cpp.
1284 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1285 "otherwise the code below doesn't make sense");
1286
1287 // We don't have floating point command-line arguments
1288 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1289 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1290 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1291 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1292
1293 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1294 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1295
1296 // We have to be careful here as these two calculations can overflow
1297 // 32-bit size_t's.
1298 double used_after_gc_d = (double) used_after_gc;
1299 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1300 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1301
1302 // Let's make sure that they are both under the max heap size, which
1303 // by default will make them fit into a size_t.
1304 double desired_capacity_upper_bound = (double) max_heap_size;
1305 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1306 desired_capacity_upper_bound);
1307 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1308 desired_capacity_upper_bound);
1309
1310 // We can now safely turn them into size_t's.
1311 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1312 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1313
1314 // This assert only makes sense here, before we adjust them
1315 // with respect to the min and max heap size.
1316 assert(minimum_desired_capacity <= maximum_desired_capacity,
1317 "minimum_desired_capacity = " SIZE_FORMAT ", "
1318 "maximum_desired_capacity = " SIZE_FORMAT,
1319 minimum_desired_capacity, maximum_desired_capacity);
1320
1321 // Should not be greater than the heap max size. No need to adjust
1322 // it with respect to the heap min size as it's a lower bound (i.e.,
1323 // we'll try to make the capacity larger than it, not smaller).
1324 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1325 // Should not be less than the heap min size. No need to adjust it
1326 // with respect to the heap max size as it's an upper bound (i.e.,
1327 // we'll try to make the capacity smaller than it, not greater).
1328 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1329
1330 if (capacity_after_gc < minimum_desired_capacity) {
1331 // Don't expand unless it's significant
1332 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1333
1334 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1335 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1336 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1337
1338 expand(expand_bytes, _workers);
1339
1340 // No expansion, now see if we want to shrink
1341 } else if (capacity_after_gc > maximum_desired_capacity) {
1342 // Capacity too large, compute shrinking size
1343 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1344
1345 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1346 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1347 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1348
1349 shrink(shrink_bytes);
1350 }
1351 }
1352
1353 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1354 AllocationContext_t context,
1355 bool do_gc,
1356 bool clear_all_soft_refs,
1357 bool expect_null_mutator_alloc_region,
1358 bool* gc_succeeded) {
1359 *gc_succeeded = true;
1360 // Let's attempt the allocation first.
1361 HeapWord* result =
1362 attempt_allocation_at_safepoint(word_size,
1363 context,
1364 expect_null_mutator_alloc_region);
1365 if (result != NULL) {
1366 assert(*gc_succeeded, "sanity");
1367 return result;
1368 }
1369
1370 // In a G1 heap, we're supposed to keep allocation from failing by
1371 // incremental pauses. Therefore, at least for now, we'll favor
1372 // expansion over collection. (This might change in the future if we can
1373 // do something smarter than full collection to satisfy a failed alloc.)
1374 result = expand_and_allocate(word_size, context);
1375 if (result != NULL) {
1376 assert(*gc_succeeded, "sanity");
1377 return result;
1378 }
1379
1380 if (do_gc) {
1381 // Expansion didn't work, we'll try to do a Full GC.
1382 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1383 clear_all_soft_refs);
1384 }
1385
1386 return NULL;
1387 }
1388
1389 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1390 AllocationContext_t context,
1391 bool* succeeded) {
1392 assert_at_safepoint(true /* should_be_vm_thread */);
1393
1394 // Attempts to allocate followed by Full GC.
1395 HeapWord* result =
1396 satisfy_failed_allocation_helper(word_size,
1397 context,
1398 true, /* do_gc */
1399 false, /* clear_all_soft_refs */
1400 false, /* expect_null_mutator_alloc_region */
1401 succeeded);
1402
1403 if (result != NULL || !*succeeded) {
1404 return result;
1405 }
1406
1407 // Attempts to allocate followed by Full GC that will collect all soft references.
1408 result = satisfy_failed_allocation_helper(word_size,
1409 context,
1410 true, /* do_gc */
1411 true, /* clear_all_soft_refs */
1412 true, /* expect_null_mutator_alloc_region */
1413 succeeded);
1414
1415 if (result != NULL || !*succeeded) {
1416 return result;
1417 }
1418
1419 // Attempts to allocate, no GC
1420 result = satisfy_failed_allocation_helper(word_size,
1421 context,
1422 false, /* do_gc */
1423 false, /* clear_all_soft_refs */
1424 true, /* expect_null_mutator_alloc_region */
1425 succeeded);
1426
1427 if (result != NULL) {
1428 assert(*succeeded, "sanity");
1429 return result;
1430 }
1431
1432 assert(!collector_policy()->should_clear_all_soft_refs(),
1433 "Flag should have been handled and cleared prior to this point");
1434
1435 // What else? We might try synchronous finalization later. If the total
1436 // space available is large enough for the allocation, then a more
1437 // complete compaction phase than we've tried so far might be
1438 // appropriate.
1439 assert(*succeeded, "sanity");
1440 return NULL;
1441 }
1442
1443 // Attempting to expand the heap sufficiently
1444 // to support an allocation of the given "word_size". If
1445 // successful, perform the allocation and return the address of the
1446 // allocated block, or else "NULL".
1447
1448 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1449 assert_at_safepoint(true /* should_be_vm_thread */);
1450
1451 _verifier->verify_region_sets_optional();
1452
1453 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1454 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1455 word_size * HeapWordSize);
1456
1457
1458 if (expand(expand_bytes, _workers)) {
1459 _hrm.verify_optional();
1460 _verifier->verify_region_sets_optional();
1461 return attempt_allocation_at_safepoint(word_size,
1462 context,
1463 false /* expect_null_mutator_alloc_region */);
1464 }
1465 return NULL;
1466 }
1467
1468 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1469 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1470 aligned_expand_bytes = align_up(aligned_expand_bytes,
1471 HeapRegion::GrainBytes);
1472
1473 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1474 expand_bytes, aligned_expand_bytes);
1475
1476 if (is_maximal_no_gc()) {
1477 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1478 return false;
1479 }
1480
1481 double expand_heap_start_time_sec = os::elapsedTime();
1482 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1483 assert(regions_to_expand > 0, "Must expand by at least one region");
1484
1485 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1486 if (expand_time_ms != NULL) {
1487 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1488 }
1489
1490 if (expanded_by > 0) {
1491 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1492 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1493 g1_policy()->record_new_heap_size(num_regions());
1494 } else {
1495 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1496
1497 // The expansion of the virtual storage space was unsuccessful.
1498 // Let's see if it was because we ran out of swap.
1499 if (G1ExitOnExpansionFailure &&
1500 _hrm.available() >= regions_to_expand) {
1501 // We had head room...
1502 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1503 }
1504 }
1505 return regions_to_expand > 0;
1506 }
1507
1508 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1509 size_t aligned_shrink_bytes =
1510 ReservedSpace::page_align_size_down(shrink_bytes);
1511 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1512 HeapRegion::GrainBytes);
1513 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1514
1515 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1516 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1517
1518
1519 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",
1520 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1521 if (num_regions_removed > 0) {
1522 g1_policy()->record_new_heap_size(num_regions());
1523 } else {
1524 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1525 }
1526 }
1527
1528 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1529 _verifier->verify_region_sets_optional();
1530
1531 // We should only reach here at the end of a Full GC which means we
1532 // should not not be holding to any GC alloc regions. The method
1533 // below will make sure of that and do any remaining clean up.
1534 _allocator->abandon_gc_alloc_regions();
1535
1536 // Instead of tearing down / rebuilding the free lists here, we
1537 // could instead use the remove_all_pending() method on free_list to
1538 // remove only the ones that we need to remove.
1539 tear_down_region_sets(true /* free_list_only */);
1540 shrink_helper(shrink_bytes);
1541 rebuild_region_sets(true /* free_list_only */);
1542
1543 _hrm.verify_optional();
1544 _verifier->verify_region_sets_optional();
1545 }
1546
1547 // Public methods.
1548
1549 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1550 CollectedHeap(),
1551 _collector_policy(collector_policy),
1552 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1553 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1554 _g1_policy(create_g1_policy(_gc_timer_stw)),
1555 _collection_set(this, _g1_policy),
1556 _dirty_card_queue_set(false),
1557 _is_alive_closure_cm(this),
1558 _is_alive_closure_stw(this),
1559 _ref_processor_cm(NULL),
1560 _ref_processor_stw(NULL),
1561 _bot(NULL),
1562 _hot_card_cache(NULL),
1563 _g1_rem_set(NULL),
1564 _cg1r(NULL),
1565 _g1mm(NULL),
1566 _preserved_marks_set(true /* in_c_heap */),
1567 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1568 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1569 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1570 _humongous_reclaim_candidates(),
1571 _has_humongous_reclaim_candidates(false),
1572 _archive_allocator(NULL),
1573 _free_regions_coming(false),
1574 _gc_time_stamp(0),
1575 _summary_bytes_used(0),
1576 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1577 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1578 _expand_heap_after_alloc_failure(true),
1579 _old_marking_cycles_started(0),
1580 _old_marking_cycles_completed(0),
1581 _in_cset_fast_test() {
1582
1583 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1584 /* are_GC_task_threads */true,
1585 /* are_ConcurrentGC_threads */false);
1586 _workers->initialize_workers();
1587 _verifier = new G1HeapVerifier(this);
1588
1589 _allocator = G1Allocator::create_allocator(this);
1590
1591 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1592
1593 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1594
1595 // Override the default _filler_array_max_size so that no humongous filler
1596 // objects are created.
1597 _filler_array_max_size = _humongous_object_threshold_in_words;
1598
1599 uint n_queues = ParallelGCThreads;
1600 _task_queues = new RefToScanQueueSet(n_queues);
1601
1602 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1603
1604 for (uint i = 0; i < n_queues; i++) {
1605 RefToScanQueue* q = new RefToScanQueue();
1606 q->initialize();
1607 _task_queues->register_queue(i, q);
1608 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1609 }
1610
1611 // Initialize the G1EvacuationFailureALot counters and flags.
1612 NOT_PRODUCT(reset_evacuation_should_fail();)
1613
1614 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1615 }
1616
1617 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1618 size_t size,
1619 size_t translation_factor) {
1620 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1621 // Allocate a new reserved space, preferring to use large pages.
1622 ReservedSpace rs(size, preferred_page_size);
1623 G1RegionToSpaceMapper* result =
1624 G1RegionToSpaceMapper::create_mapper(rs,
1625 size,
1626 rs.alignment(),
1627 HeapRegion::GrainBytes,
1628 translation_factor,
1629 mtGC);
1630
1631 os::trace_page_sizes_for_requested_size(description,
1632 size,
1633 preferred_page_size,
1634 rs.alignment(),
1635 rs.base(),
1636 rs.size());
1637
1638 return result;
1639 }
1640
1641 jint G1CollectedHeap::initialize_concurrent_refinement() {
1642 jint ecode = JNI_OK;
1643 _cg1r = ConcurrentG1Refine::create(&ecode);
1644 return ecode;
1645 }
1646
1647 jint G1CollectedHeap::initialize() {
1648 CollectedHeap::pre_initialize();
1649 os::enable_vtime();
1650
1651 // Necessary to satisfy locking discipline assertions.
1652
1653 MutexLocker x(Heap_lock);
1654
1655 // While there are no constraints in the GC code that HeapWordSize
1656 // be any particular value, there are multiple other areas in the
1657 // system which believe this to be true (e.g. oop->object_size in some
1658 // cases incorrectly returns the size in wordSize units rather than
1659 // HeapWordSize).
1660 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1661
1662 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1663 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1664 size_t heap_alignment = collector_policy()->heap_alignment();
1665
1666 // Ensure that the sizes are properly aligned.
1667 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1669 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1670
1671 // Reserve the maximum.
1672
1673 // When compressed oops are enabled, the preferred heap base
1674 // is calculated by subtracting the requested size from the
1675 // 32Gb boundary and using the result as the base address for
1676 // heap reservation. If the requested size is not aligned to
1677 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1678 // into the ReservedHeapSpace constructor) then the actual
1679 // base of the reserved heap may end up differing from the
1680 // address that was requested (i.e. the preferred heap base).
1681 // If this happens then we could end up using a non-optimal
1682 // compressed oops mode.
1683
1684 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1685 heap_alignment);
1686
1687 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1688
1689 // Create the barrier set for the entire reserved region.
1690 G1SATBCardTableLoggingModRefBS* bs
1691 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1692 bs->initialize();
1693 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "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_barrier_set()->initialize(cardtable_storage);
1741 // Do later initialization work for concurrent refinement.
1742 _hot_card_cache->initialize(card_counts_storage);
1743
1744 // 6843694 - ensure that the maximum region index can fit
1745 // in the remembered set structures.
1746 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1747 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1748
1749 // Also create a G1 rem set.
1750 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1751 _g1_rem_set->initialize(max_capacity(), max_regions());
1752
1753 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1754 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1755 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1756 "too many cards per region");
1757
1758 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1759
1760 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1761
1762 {
1763 HeapWord* start = _hrm.reserved().start();
1764 HeapWord* end = _hrm.reserved().end();
1765 size_t granularity = HeapRegion::GrainBytes;
1766
1767 _in_cset_fast_test.initialize(start, end, granularity);
1768 _humongous_reclaim_candidates.initialize(start, end, granularity);
1769 }
1770
1771 // Create the G1ConcurrentMark data structure and thread.
1772 // (Must do this late, so that "max_regions" is defined.)
1773 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1774 if (_cm == NULL || !_cm->completed_initialization()) {
1775 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1776 return JNI_ENOMEM;
1777 }
1778 _cmThread = _cm->cmThread();
1779
1780 // Now expand into the initial heap size.
1781 if (!expand(init_byte_size, _workers)) {
1782 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1783 return JNI_ENOMEM;
1784 }
1785
1786 // Perform any initialization actions delegated to the policy.
1787 g1_policy()->init(this, &_collection_set);
1788
1789 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1790 SATB_Q_FL_lock,
1791 G1SATBProcessCompletedThreshold,
1792 Shared_SATB_Q_lock);
1793
1794 jint ecode = initialize_concurrent_refinement();
1795 if (ecode != JNI_OK) {
1796 return ecode;
1797 }
1798
1799 JavaThread::dirty_card_queue_set().initialize(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 &JavaThread::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 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1854 return HeapRegion::max_region_size();
1855 }
1856
1857 void G1CollectedHeap::post_initialize() {
1858 ref_processing_init();
1859 }
1860
1861 void G1CollectedHeap::ref_processing_init() {
1862 // Reference processing in G1 currently works as follows:
1863 //
1864 // * There are two reference processor instances. One is
1865 // used to record and process discovered references
1866 // during concurrent marking; the other is used to
1867 // record and process references during STW pauses
1868 // (both full and incremental).
1869 // * Both ref processors need to 'span' the entire heap as
1870 // the regions in the collection set may be dotted around.
1871 //
1872 // * For the concurrent marking ref processor:
1873 // * Reference discovery is enabled at initial marking.
1874 // * Reference discovery is disabled and the discovered
1875 // references processed etc during remarking.
1876 // * Reference discovery is MT (see below).
1877 // * Reference discovery requires a barrier (see below).
1878 // * Reference processing may or may not be MT
1879 // (depending on the value of ParallelRefProcEnabled
1880 // and ParallelGCThreads).
1881 // * A full GC disables reference discovery by the CM
1882 // ref processor and abandons any entries on it's
1883 // discovered lists.
1884 //
1885 // * For the STW processor:
1886 // * Non MT discovery is enabled at the start of a full GC.
1887 // * Processing and enqueueing during a full GC is non-MT.
1888 // * During a full GC, references are processed after marking.
1889 //
1890 // * Discovery (may or may not be MT) is enabled at the start
1891 // of an incremental evacuation pause.
1892 // * References are processed near the end of a STW evacuation pause.
1893 // * For both types of GC:
1894 // * Discovery is atomic - i.e. not concurrent.
1895 // * Reference discovery will not need a barrier.
1896
1897 MemRegion mr = reserved_region();
1898
1899 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1900
1901 // Concurrent Mark ref processor
1902 _ref_processor_cm =
1903 new ReferenceProcessor(mr, // span
1904 mt_processing,
1905 // mt processing
1906 ParallelGCThreads,
1907 // degree of mt processing
1908 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1909 // mt discovery
1910 MAX2(ParallelGCThreads, ConcGCThreads),
1911 // degree of mt discovery
1912 false,
1913 // Reference discovery is not atomic
1914 &_is_alive_closure_cm);
1915 // is alive closure
1916 // (for efficiency/performance)
1917
1918 // STW ref processor
1919 _ref_processor_stw =
1920 new ReferenceProcessor(mr, // span
1921 mt_processing,
1922 // mt processing
1923 ParallelGCThreads,
1924 // degree of mt processing
1925 (ParallelGCThreads > 1),
1926 // mt discovery
1927 ParallelGCThreads,
1928 // degree of mt discovery
1929 true,
1930 // Reference discovery is atomic
1931 &_is_alive_closure_stw);
1932 // is alive closure
1933 // (for efficiency/performance)
1934 }
1935
1936 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1937 return _collector_policy;
1938 }
1939
1940 size_t G1CollectedHeap::capacity() const {
1941 return _hrm.length() * HeapRegion::GrainBytes;
1942 }
1943
1944 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1945 hr->reset_gc_time_stamp();
1946 }
1947
1948 #ifndef PRODUCT
1949
1950 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1951 private:
1952 unsigned _gc_time_stamp;
1953 bool _failures;
1954
1955 public:
1956 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1957 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1958
1959 virtual bool doHeapRegion(HeapRegion* hr) {
1960 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1961 if (_gc_time_stamp != region_gc_time_stamp) {
1962 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1963 region_gc_time_stamp, _gc_time_stamp);
1964 _failures = true;
1965 }
1966 return false;
1967 }
1968
1969 bool failures() { return _failures; }
1970 };
1971
1972 void G1CollectedHeap::check_gc_time_stamps() {
1973 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1974 heap_region_iterate(&cl);
1975 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1976 }
1977 #endif // PRODUCT
1978
1979 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1980 _hot_card_cache->drain(cl, worker_i);
1981 }
1982
1983 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1984 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1985 size_t n_completed_buffers = 0;
1986 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1987 n_completed_buffers++;
1988 }
1989 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1990 dcqs.clear_n_completed_buffers();
1991 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1992 }
1993
1994 // Computes the sum of the storage used by the various regions.
1995 size_t G1CollectedHeap::used() const {
1996 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1997 if (_archive_allocator != NULL) {
1998 result += _archive_allocator->used();
1999 }
2000 return result;
2001 }
2002
2003 size_t G1CollectedHeap::used_unlocked() const {
2004 return _summary_bytes_used;
2005 }
2006
2007 class SumUsedClosure: public HeapRegionClosure {
2008 size_t _used;
2009 public:
2010 SumUsedClosure() : _used(0) {}
2011 bool doHeapRegion(HeapRegion* r) {
2012 _used += r->used();
2013 return false;
2014 }
2015 size_t result() { return _used; }
2016 };
2017
2018 size_t G1CollectedHeap::recalculate_used() const {
2019 double recalculate_used_start = os::elapsedTime();
2020
2021 SumUsedClosure blk;
2022 heap_region_iterate(&blk);
2023
2024 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2025 return blk.result();
2026 }
2027
2028 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2029 switch (cause) {
2030 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2031 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2032 case GCCause::_update_allocation_context_stats_inc: return true;
2033 case GCCause::_wb_conc_mark: return true;
2034 default : return false;
2035 }
2036 }
2037
2038 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2039 switch (cause) {
2040 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2041 case GCCause::_g1_humongous_allocation: return true;
2042 default: return is_user_requested_concurrent_full_gc(cause);
2043 }
2044 }
2045
2046 #ifndef PRODUCT
2047 void G1CollectedHeap::allocate_dummy_regions() {
2048 // Let's fill up most of the region
2049 size_t word_size = HeapRegion::GrainWords - 1024;
2050 // And as a result the region we'll allocate will be humongous.
2051 guarantee(is_humongous(word_size), "sanity");
2052
2053 // _filler_array_max_size is set to humongous object threshold
2054 // but temporarily change it to use CollectedHeap::fill_with_object().
2055 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2056
2057 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2058 // Let's use the existing mechanism for the allocation
2059 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2060 AllocationContext::system());
2061 if (dummy_obj != NULL) {
2062 MemRegion mr(dummy_obj, word_size);
2063 CollectedHeap::fill_with_object(mr);
2064 } else {
2065 // If we can't allocate once, we probably cannot allocate
2066 // again. Let's get out of the loop.
2067 break;
2068 }
2069 }
2070 }
2071 #endif // !PRODUCT
2072
2073 void G1CollectedHeap::increment_old_marking_cycles_started() {
2074 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2075 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2076 "Wrong marking cycle count (started: %d, completed: %d)",
2077 _old_marking_cycles_started, _old_marking_cycles_completed);
2078
2079 _old_marking_cycles_started++;
2080 }
2081
2082 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2083 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2084
2085 // We assume that if concurrent == true, then the caller is a
2086 // concurrent thread that was joined the Suspendible Thread
2087 // Set. If there's ever a cheap way to check this, we should add an
2088 // assert here.
2089
2090 // Given that this method is called at the end of a Full GC or of a
2091 // concurrent cycle, and those can be nested (i.e., a Full GC can
2092 // interrupt a concurrent cycle), the number of full collections
2093 // completed should be either one (in the case where there was no
2094 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2095 // behind the number of full collections started.
2096
2097 // This is the case for the inner caller, i.e. a Full GC.
2098 assert(concurrent ||
2099 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2100 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2101 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2102 "is inconsistent with _old_marking_cycles_completed = %u",
2103 _old_marking_cycles_started, _old_marking_cycles_completed);
2104
2105 // This is the case for the outer caller, i.e. the concurrent cycle.
2106 assert(!concurrent ||
2107 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2108 "for outer caller (concurrent cycle): "
2109 "_old_marking_cycles_started = %u "
2110 "is inconsistent with _old_marking_cycles_completed = %u",
2111 _old_marking_cycles_started, _old_marking_cycles_completed);
2112
2113 _old_marking_cycles_completed += 1;
2114
2115 // We need to clear the "in_progress" flag in the CM thread before
2116 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2117 // is set) so that if a waiter requests another System.gc() it doesn't
2118 // incorrectly see that a marking cycle is still in progress.
2119 if (concurrent) {
2120 _cmThread->set_idle();
2121 }
2122
2123 // This notify_all() will ensure that a thread that called
2124 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2125 // and it's waiting for a full GC to finish will be woken up. It is
2126 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2127 FullGCCount_lock->notify_all();
2128 }
2129
2130 void G1CollectedHeap::collect(GCCause::Cause cause) {
2131 assert_heap_not_locked();
2132
2133 uint gc_count_before;
2134 uint old_marking_count_before;
2135 uint full_gc_count_before;
2136 bool retry_gc;
2137
2138 do {
2139 retry_gc = false;
2140
2141 {
2142 MutexLocker ml(Heap_lock);
2143
2144 // Read the GC count while holding the Heap_lock
2145 gc_count_before = total_collections();
2146 full_gc_count_before = total_full_collections();
2147 old_marking_count_before = _old_marking_cycles_started;
2148 }
2149
2150 if (should_do_concurrent_full_gc(cause)) {
2151 // Schedule an initial-mark evacuation pause that will start a
2152 // concurrent cycle. We're setting word_size to 0 which means that
2153 // we are not requesting a post-GC allocation.
2154 VM_G1IncCollectionPause op(gc_count_before,
2155 0, /* word_size */
2156 true, /* should_initiate_conc_mark */
2157 g1_policy()->max_pause_time_ms(),
2158 cause);
2159 op.set_allocation_context(AllocationContext::current());
2160
2161 VMThread::execute(&op);
2162 if (!op.pause_succeeded()) {
2163 if (old_marking_count_before == _old_marking_cycles_started) {
2164 retry_gc = op.should_retry_gc();
2165 } else {
2166 // A Full GC happened while we were trying to schedule the
2167 // initial-mark GC. No point in starting a new cycle given
2168 // that the whole heap was collected anyway.
2169 }
2170
2171 if (retry_gc) {
2172 if (GCLocker::is_active_and_needs_gc()) {
2173 GCLocker::stall_until_clear();
2174 }
2175 }
2176 }
2177 } else {
2178 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2179 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2180
2181 // Schedule a standard evacuation pause. We're setting word_size
2182 // to 0 which means that we are not requesting a post-GC allocation.
2183 VM_G1IncCollectionPause op(gc_count_before,
2184 0, /* word_size */
2185 false, /* should_initiate_conc_mark */
2186 g1_policy()->max_pause_time_ms(),
2187 cause);
2188 VMThread::execute(&op);
2189 } else {
2190 // Schedule a Full GC.
2191 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2192 VMThread::execute(&op);
2193 }
2194 }
2195 } while (retry_gc);
2196 }
2197
2198 bool G1CollectedHeap::is_in(const void* p) const {
2199 if (_hrm.reserved().contains(p)) {
2200 // Given that we know that p is in the reserved space,
2201 // heap_region_containing() should successfully
2202 // return the containing region.
2203 HeapRegion* hr = heap_region_containing(p);
2204 return hr->is_in(p);
2205 } else {
2206 return false;
2207 }
2208 }
2209
2210 #ifdef ASSERT
2211 bool G1CollectedHeap::is_in_exact(const void* p) const {
2212 bool contains = reserved_region().contains(p);
2213 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2214 if (contains && available) {
2215 return true;
2216 } else {
2217 return false;
2218 }
2219 }
2220 #endif
2221
2222 // Iteration functions.
2223
2224 // Iterates an ObjectClosure over all objects within a HeapRegion.
2225
2226 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2227 ObjectClosure* _cl;
2228 public:
2229 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2230 bool doHeapRegion(HeapRegion* r) {
2231 if (!r->is_continues_humongous()) {
2232 r->object_iterate(_cl);
2233 }
2234 return false;
2235 }
2236 };
2237
2238 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2239 IterateObjectClosureRegionClosure blk(cl);
2240 heap_region_iterate(&blk);
2241 }
2242
2243 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2244 _hrm.iterate(cl);
2245 }
2246
2247 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2248 uint worker_id,
2249 HeapRegionClaimer *hrclaimer) const {
2250 _hrm.par_iterate(cl, worker_id, hrclaimer);
2251 }
2252
2253 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2254 _collection_set.iterate(cl);
2255 }
2256
2257 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2258 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2259 }
2260
2261 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2262 HeapRegion* result = _hrm.next_region_in_heap(from);
2263 while (result != NULL && result->is_pinned()) {
2264 result = _hrm.next_region_in_heap(result);
2265 }
2266 return result;
2267 }
2268
2269 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2270 HeapRegion* hr = heap_region_containing(addr);
2271 return hr->block_start(addr);
2272 }
2273
2274 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2275 HeapRegion* hr = heap_region_containing(addr);
2276 return hr->block_size(addr);
2277 }
2278
2279 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2280 HeapRegion* hr = heap_region_containing(addr);
2281 return hr->block_is_obj(addr);
2282 }
2283
2284 bool G1CollectedHeap::supports_tlab_allocation() const {
2285 return true;
2286 }
2287
2288 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2289 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2290 }
2291
2292 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2293 return _eden.length() * HeapRegion::GrainBytes;
2294 }
2295
2296 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2297 // must be equal to the humongous object limit.
2298 size_t G1CollectedHeap::max_tlab_size() const {
2299 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2300 }
2301
2302 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2303 AllocationContext_t context = AllocationContext::current();
2304 return _allocator->unsafe_max_tlab_alloc(context);
2305 }
2306
2307 size_t G1CollectedHeap::max_capacity() const {
2308 return _hrm.reserved().byte_size();
2309 }
2310
2311 jlong G1CollectedHeap::millis_since_last_gc() {
2312 // See the notes in GenCollectedHeap::millis_since_last_gc()
2313 // for more information about the implementation.
2314 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2315 _g1_policy->collection_pause_end_millis();
2316 if (ret_val < 0) {
2317 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2318 ". returning zero instead.", ret_val);
2319 return 0;
2320 }
2321 return ret_val;
2322 }
2323
2324 void G1CollectedHeap::prepare_for_verify() {
2325 _verifier->prepare_for_verify();
2326 }
2327
2328 void G1CollectedHeap::verify(VerifyOption vo) {
2329 _verifier->verify(vo);
2330 }
2331
2332 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2333 return true;
2334 }
2335
2336 const char* const* G1CollectedHeap::concurrent_phases() const {
2337 return _cmThread->concurrent_phases();
2338 }
2339
2340 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2341 return _cmThread->request_concurrent_phase(phase);
2342 }
2343
2344 class PrintRegionClosure: public HeapRegionClosure {
2345 outputStream* _st;
2346 public:
2347 PrintRegionClosure(outputStream* st) : _st(st) {}
2348 bool doHeapRegion(HeapRegion* r) {
2349 r->print_on(_st);
2350 return false;
2351 }
2352 };
2353
2354 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2355 const HeapRegion* hr,
2356 const VerifyOption vo) const {
2357 switch (vo) {
2358 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2359 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2360 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2361 default: ShouldNotReachHere();
2362 }
2363 return false; // keep some compilers happy
2364 }
2365
2366 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2367 const VerifyOption vo) const {
2368 switch (vo) {
2369 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2370 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2371 case VerifyOption_G1UseMarkWord: {
2372 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2373 return !obj->is_gc_marked() && !hr->is_archive();
2374 }
2375 default: ShouldNotReachHere();
2376 }
2377 return false; // keep some compilers happy
2378 }
2379
2380 void G1CollectedHeap::print_heap_regions() const {
2381 LogTarget(Trace, gc, heap, region) lt;
2382 if (lt.is_enabled()) {
2383 LogStream ls(lt);
2384 print_regions_on(&ls);
2385 }
2386 }
2387
2388 void G1CollectedHeap::print_on(outputStream* st) const {
2389 st->print(" %-20s", "garbage-first heap");
2390 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2391 capacity()/K, used_unlocked()/K);
2392 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2393 p2i(_hrm.reserved().start()),
2394 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2395 p2i(_hrm.reserved().end()));
2396 st->cr();
2397 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2398 uint young_regions = young_regions_count();
2399 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2400 (size_t) young_regions * HeapRegion::GrainBytes / K);
2401 uint survivor_regions = survivor_regions_count();
2402 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2403 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2404 st->cr();
2405 MetaspaceAux::print_on(st);
2406 }
2407
2408 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2409 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2410 "HS=humongous(starts), HC=humongous(continues), "
2411 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2412 "AC=allocation context, "
2413 "TAMS=top-at-mark-start (previous, next)");
2414 PrintRegionClosure blk(st);
2415 heap_region_iterate(&blk);
2416 }
2417
2418 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2419 print_on(st);
2420
2421 // Print the per-region information.
2422 print_regions_on(st);
2423 }
2424
2425 void G1CollectedHeap::print_on_error(outputStream* st) const {
2426 this->CollectedHeap::print_on_error(st);
2427
2428 if (_cm != NULL) {
2429 st->cr();
2430 _cm->print_on_error(st);
2431 }
2432 }
2433
2434 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2435 workers()->print_worker_threads_on(st);
2436 _cmThread->print_on(st);
2437 st->cr();
2438 _cm->print_worker_threads_on(st);
2439 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2440 if (G1StringDedup::is_enabled()) {
2441 G1StringDedup::print_worker_threads_on(st);
2442 }
2443 }
2444
2445 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2446 workers()->threads_do(tc);
2447 tc->do_thread(_cmThread);
2448 _cm->threads_do(tc);
2449 _cg1r->threads_do(tc); // also iterates over the sample thread
2450 if (G1StringDedup::is_enabled()) {
2451 G1StringDedup::threads_do(tc);
2452 }
2453 }
2454
2455 void G1CollectedHeap::print_tracing_info() const {
2456 g1_rem_set()->print_summary_info();
2457 concurrent_mark()->print_summary_info();
2458 }
2459
2460 #ifndef PRODUCT
2461 // Helpful for debugging RSet issues.
2462
2463 class PrintRSetsClosure : public HeapRegionClosure {
2464 private:
2465 const char* _msg;
2466 size_t _occupied_sum;
2467
2468 public:
2469 bool doHeapRegion(HeapRegion* r) {
2470 HeapRegionRemSet* hrrs = r->rem_set();
2471 size_t occupied = hrrs->occupied();
2472 _occupied_sum += occupied;
2473
2474 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2475 if (occupied == 0) {
2476 tty->print_cr(" RSet is empty");
2477 } else {
2478 hrrs->print();
2479 }
2480 tty->print_cr("----------");
2481 return false;
2482 }
2483
2484 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2485 tty->cr();
2486 tty->print_cr("========================================");
2487 tty->print_cr("%s", msg);
2488 tty->cr();
2489 }
2490
2491 ~PrintRSetsClosure() {
2492 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2493 tty->print_cr("========================================");
2494 tty->cr();
2495 }
2496 };
2497
2498 void G1CollectedHeap::print_cset_rsets() {
2499 PrintRSetsClosure cl("Printing CSet RSets");
2500 collection_set_iterate(&cl);
2501 }
2502
2503 void G1CollectedHeap::print_all_rsets() {
2504 PrintRSetsClosure cl("Printing All RSets");;
2505 heap_region_iterate(&cl);
2506 }
2507 #endif // PRODUCT
2508
2509 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2510
2511 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2512 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2513 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2514
2515 size_t eden_capacity_bytes =
2516 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2517
2518 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2519 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2520 eden_capacity_bytes, survivor_used_bytes, num_regions());
2521 }
2522
2523 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2524 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2525 stats->unused(), stats->used(), stats->region_end_waste(),
2526 stats->regions_filled(), stats->direct_allocated(),
2527 stats->failure_used(), stats->failure_waste());
2528 }
2529
2530 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2531 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2532 gc_tracer->report_gc_heap_summary(when, heap_summary);
2533
2534 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2535 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2536 }
2537
2538 G1CollectedHeap* G1CollectedHeap::heap() {
2539 CollectedHeap* heap = Universe::heap();
2540 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2541 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2542 return (G1CollectedHeap*)heap;
2543 }
2544
2545 void G1CollectedHeap::gc_prologue(bool full) {
2546 // always_do_update_barrier = false;
2547 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2548
2549 // This summary needs to be printed before incrementing total collections.
2550 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2551
2552 // Update common counters.
2553 increment_total_collections(full /* full gc */);
2554 if (full) {
2555 increment_old_marking_cycles_started();
2556 reset_gc_time_stamp();
2557 } else {
2558 increment_gc_time_stamp();
2559 }
2560
2561 // Fill TLAB's and such
2562 double start = os::elapsedTime();
2563 accumulate_statistics_all_tlabs();
2564 ensure_parsability(true);
2565 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2566 }
2567
2568 void G1CollectedHeap::gc_epilogue(bool full) {
2569 // Update common counters.
2570 if (full) {
2571 // Update the number of full collections that have been completed.
2572 increment_old_marking_cycles_completed(false /* concurrent */);
2573 }
2574
2575 // We are at the end of the GC. Total collections has already been increased.
2576 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2577
2578 // FIXME: what is this about?
2579 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2580 // is set.
2581 #if defined(COMPILER2) || INCLUDE_JVMCI
2582 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2583 #endif
2584 // always_do_update_barrier = true;
2585
2586 double start = os::elapsedTime();
2587 resize_all_tlabs();
2588 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2589
2590 allocation_context_stats().update(full);
2591
2592 MemoryService::track_memory_usage();
2593 // We have just completed a GC. Update the soft reference
2594 // policy with the new heap occupancy
2595 Universe::update_heap_info_at_gc();
2596 }
2597
2598 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2599 uint gc_count_before,
2600 bool* succeeded,
2601 GCCause::Cause gc_cause) {
2602 assert_heap_not_locked_and_not_at_safepoint();
2603 VM_G1IncCollectionPause op(gc_count_before,
2604 word_size,
2605 false, /* should_initiate_conc_mark */
2606 g1_policy()->max_pause_time_ms(),
2607 gc_cause);
2608
2609 op.set_allocation_context(AllocationContext::current());
2610 VMThread::execute(&op);
2611
2612 HeapWord* result = op.result();
2613 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2614 assert(result == NULL || ret_succeeded,
2615 "the result should be NULL if the VM did not succeed");
2616 *succeeded = ret_succeeded;
2617
2618 assert_heap_not_locked();
2619 return result;
2620 }
2621
2622 void
2623 G1CollectedHeap::doConcurrentMark() {
2624 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2625 if (!_cmThread->in_progress()) {
2626 _cmThread->set_started();
2627 CGC_lock->notify();
2628 }
2629 }
2630
2631 size_t G1CollectedHeap::pending_card_num() {
2632 size_t extra_cards = 0;
2633 JavaThread *curr = Threads::first();
2634 while (curr != NULL) {
2635 DirtyCardQueue& dcq = curr->dirty_card_queue();
2636 extra_cards += dcq.size();
2637 curr = curr->next();
2638 }
2639 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2640 size_t buffer_size = dcqs.buffer_size();
2641 size_t buffer_num = dcqs.completed_buffers_num();
2642
2643 return buffer_size * buffer_num + extra_cards;
2644 }
2645
2646 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2647 private:
2648 size_t _total_humongous;
2649 size_t _candidate_humongous;
2650
2651 DirtyCardQueue _dcq;
2652
2653 // We don't nominate objects with many remembered set entries, on
2654 // the assumption that such objects are likely still live.
2655 bool is_remset_small(HeapRegion* region) const {
2656 HeapRegionRemSet* const rset = region->rem_set();
2657 return G1EagerReclaimHumongousObjectsWithStaleRefs
2658 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2659 : rset->is_empty();
2660 }
2661
2662 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2663 assert(region->is_starts_humongous(), "Must start a humongous object");
2664
2665 oop obj = oop(region->bottom());
2666
2667 // Dead objects cannot be eager reclaim candidates. Due to class
2668 // unloading it is unsafe to query their classes so we return early.
2669 if (heap->is_obj_dead(obj, region)) {
2670 return false;
2671 }
2672
2673 // Candidate selection must satisfy the following constraints
2674 // while concurrent marking is in progress:
2675 //
2676 // * In order to maintain SATB invariants, an object must not be
2677 // reclaimed if it was allocated before the start of marking and
2678 // has not had its references scanned. Such an object must have
2679 // its references (including type metadata) scanned to ensure no
2680 // live objects are missed by the marking process. Objects
2681 // allocated after the start of concurrent marking don't need to
2682 // be scanned.
2683 //
2684 // * An object must not be reclaimed if it is on the concurrent
2685 // mark stack. Objects allocated after the start of concurrent
2686 // marking are never pushed on the mark stack.
2687 //
2688 // Nominating only objects allocated after the start of concurrent
2689 // marking is sufficient to meet both constraints. This may miss
2690 // some objects that satisfy the constraints, but the marking data
2691 // structures don't support efficiently performing the needed
2692 // additional tests or scrubbing of the mark stack.
2693 //
2694 // However, we presently only nominate is_typeArray() objects.
2695 // A humongous object containing references induces remembered
2696 // set entries on other regions. In order to reclaim such an
2697 // object, those remembered sets would need to be cleaned up.
2698 //
2699 // We also treat is_typeArray() objects specially, allowing them
2700 // to be reclaimed even if allocated before the start of
2701 // concurrent mark. For this we rely on mark stack insertion to
2702 // exclude is_typeArray() objects, preventing reclaiming an object
2703 // that is in the mark stack. We also rely on the metadata for
2704 // such objects to be built-in and so ensured to be kept live.
2705 // Frequent allocation and drop of large binary blobs is an
2706 // important use case for eager reclaim, and this special handling
2707 // may reduce needed headroom.
2708
2709 return obj->is_typeArray() && is_remset_small(region);
2710 }
2711
2712 public:
2713 RegisterHumongousWithInCSetFastTestClosure()
2714 : _total_humongous(0),
2715 _candidate_humongous(0),
2716 _dcq(&JavaThread::dirty_card_queue_set()) {
2717 }
2718
2719 virtual bool doHeapRegion(HeapRegion* r) {
2720 if (!r->is_starts_humongous()) {
2721 return false;
2722 }
2723 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2724
2725 bool is_candidate = humongous_region_is_candidate(g1h, r);
2726 uint rindex = r->hrm_index();
2727 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2728 if (is_candidate) {
2729 _candidate_humongous++;
2730 g1h->register_humongous_region_with_cset(rindex);
2731 // Is_candidate already filters out humongous object with large remembered sets.
2732 // If we have a humongous object with a few remembered sets, we simply flush these
2733 // remembered set entries into the DCQS. That will result in automatic
2734 // re-evaluation of their remembered set entries during the following evacuation
2735 // phase.
2736 if (!r->rem_set()->is_empty()) {
2737 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2738 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2739 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2740 HeapRegionRemSetIterator hrrs(r->rem_set());
2741 size_t card_index;
2742 while (hrrs.has_next(card_index)) {
2743 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2744 // The remembered set might contain references to already freed
2745 // regions. Filter out such entries to avoid failing card table
2746 // verification.
2747 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2748 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2749 *card_ptr = CardTableModRefBS::dirty_card_val();
2750 _dcq.enqueue(card_ptr);
2751 }
2752 }
2753 }
2754 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2755 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2756 hrrs.n_yielded(), r->rem_set()->occupied());
2757 r->rem_set()->clear_locked();
2758 }
2759 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2760 }
2761 _total_humongous++;
2762
2763 return false;
2764 }
2765
2766 size_t total_humongous() const { return _total_humongous; }
2767 size_t candidate_humongous() const { return _candidate_humongous; }
2768
2769 void flush_rem_set_entries() { _dcq.flush(); }
2770 };
2771
2772 void G1CollectedHeap::register_humongous_regions_with_cset() {
2773 if (!G1EagerReclaimHumongousObjects) {
2774 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2775 return;
2776 }
2777 double time = os::elapsed_counter();
2778
2779 // Collect reclaim candidate information and register candidates with cset.
2780 RegisterHumongousWithInCSetFastTestClosure cl;
2781 heap_region_iterate(&cl);
2782
2783 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2784 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2785 cl.total_humongous(),
2786 cl.candidate_humongous());
2787 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2788
2789 // Finally flush all remembered set entries to re-check into the global DCQS.
2790 cl.flush_rem_set_entries();
2791 }
2792
2793 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2794 public:
2795 bool doHeapRegion(HeapRegion* hr) {
2796 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2797 hr->verify_rem_set();
2798 }
2799 return false;
2800 }
2801 };
2802
2803 uint G1CollectedHeap::num_task_queues() const {
2804 return _task_queues->size();
2805 }
2806
2807 #if TASKQUEUE_STATS
2808 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2809 st->print_raw_cr("GC Task Stats");
2810 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2811 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2812 }
2813
2814 void G1CollectedHeap::print_taskqueue_stats() const {
2815 if (!log_is_enabled(Trace, gc, task, stats)) {
2816 return;
2817 }
2818 Log(gc, task, stats) log;
2819 ResourceMark rm;
2820 LogStream ls(log.trace());
2821 outputStream* st = &ls;
2822
2823 print_taskqueue_stats_hdr(st);
2824
2825 TaskQueueStats totals;
2826 const uint n = num_task_queues();
2827 for (uint i = 0; i < n; ++i) {
2828 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2829 totals += task_queue(i)->stats;
2830 }
2831 st->print_raw("tot "); totals.print(st); st->cr();
2832
2833 DEBUG_ONLY(totals.verify());
2834 }
2835
2836 void G1CollectedHeap::reset_taskqueue_stats() {
2837 const uint n = num_task_queues();
2838 for (uint i = 0; i < n; ++i) {
2839 task_queue(i)->stats.reset();
2840 }
2841 }
2842 #endif // TASKQUEUE_STATS
2843
2844 void G1CollectedHeap::wait_for_root_region_scanning() {
2845 double scan_wait_start = os::elapsedTime();
2846 // We have to wait until the CM threads finish scanning the
2847 // root regions as it's the only way to ensure that all the
2848 // objects on them have been correctly scanned before we start
2849 // moving them during the GC.
2850 bool waited = _cm->root_regions()->wait_until_scan_finished();
2851 double wait_time_ms = 0.0;
2852 if (waited) {
2853 double scan_wait_end = os::elapsedTime();
2854 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2855 }
2856 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2857 }
2858
2859 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2860 private:
2861 G1HRPrinter* _hr_printer;
2862 public:
2863 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2864
2865 virtual bool doHeapRegion(HeapRegion* r) {
2866 _hr_printer->cset(r);
2867 return false;
2868 }
2869 };
2870
2871 void G1CollectedHeap::start_new_collection_set() {
2872 collection_set()->start_incremental_building();
2873
2874 clear_cset_fast_test();
2875
2876 guarantee(_eden.length() == 0, "eden should have been cleared");
2877 g1_policy()->transfer_survivors_to_cset(survivor());
2878 }
2879
2880 bool
2881 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2882 assert_at_safepoint(true /* should_be_vm_thread */);
2883 guarantee(!is_gc_active(), "collection is not reentrant");
2884
2885 if (GCLocker::check_active_before_gc()) {
2886 return false;
2887 }
2888
2889 _gc_timer_stw->register_gc_start();
2890
2891 GCIdMark gc_id_mark;
2892 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2893
2894 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2895 ResourceMark rm;
2896
2897 g1_policy()->note_gc_start();
2898
2899 wait_for_root_region_scanning();
2900
2901 print_heap_before_gc();
2902 print_heap_regions();
2903 trace_heap_before_gc(_gc_tracer_stw);
2904
2905 _verifier->verify_region_sets_optional();
2906 _verifier->verify_dirty_young_regions();
2907
2908 // We should not be doing initial mark unless the conc mark thread is running
2909 if (!_cmThread->should_terminate()) {
2910 // This call will decide whether this pause is an initial-mark
2911 // pause. If it is, during_initial_mark_pause() will return true
2912 // for the duration of this pause.
2913 g1_policy()->decide_on_conc_mark_initiation();
2914 }
2915
2916 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2917 assert(!collector_state()->during_initial_mark_pause() ||
2918 collector_state()->gcs_are_young(), "sanity");
2919
2920 // We also do not allow mixed GCs during marking.
2921 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2922
2923 // Record whether this pause is an initial mark. When the current
2924 // thread has completed its logging output and it's safe to signal
2925 // the CM thread, the flag's value in the policy has been reset.
2926 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2927
2928 // Inner scope for scope based logging, timers, and stats collection
2929 {
2930 EvacuationInfo evacuation_info;
2931
2932 if (collector_state()->during_initial_mark_pause()) {
2933 // We are about to start a marking cycle, so we increment the
2934 // full collection counter.
2935 increment_old_marking_cycles_started();
2936 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2937 }
2938
2939 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2940
2941 GCTraceCPUTime tcpu;
2942
2943 FormatBuffer<> gc_string("Pause ");
2944 if (collector_state()->during_initial_mark_pause()) {
2945 gc_string.append("Initial Mark");
2946 } else if (collector_state()->gcs_are_young()) {
2947 gc_string.append("Young");
2948 } else {
2949 gc_string.append("Mixed");
2950 }
2951 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2952
2953 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2954 workers()->active_workers(),
2955 Threads::number_of_non_daemon_threads());
2956 workers()->update_active_workers(active_workers);
2957 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2958
2959 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2960 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2961
2962 // If the secondary_free_list is not empty, append it to the
2963 // free_list. No need to wait for the cleanup operation to finish;
2964 // the region allocation code will check the secondary_free_list
2965 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2966 // set, skip this step so that the region allocation code has to
2967 // get entries from the secondary_free_list.
2968 if (!G1StressConcRegionFreeing) {
2969 append_secondary_free_list_if_not_empty_with_lock();
2970 }
2971
2972 G1HeapTransition heap_transition(this);
2973 size_t heap_used_bytes_before_gc = used();
2974
2975 // Don't dynamically change the number of GC threads this early. A value of
2976 // 0 is used to indicate serial work. When parallel work is done,
2977 // it will be set.
2978
2979 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2980 IsGCActiveMark x;
2981
2982 gc_prologue(false);
2983
2984 if (VerifyRememberedSets) {
2985 log_info(gc, verify)("[Verifying RemSets before GC]");
2986 VerifyRegionRemSetClosure v_cl;
2987 heap_region_iterate(&v_cl);
2988 }
2989
2990 _verifier->verify_before_gc();
2991
2992 _verifier->check_bitmaps("GC Start");
2993
2994 #if defined(COMPILER2) || INCLUDE_JVMCI
2995 DerivedPointerTable::clear();
2996 #endif
2997
2998 // Please see comment in g1CollectedHeap.hpp and
2999 // G1CollectedHeap::ref_processing_init() to see how
3000 // reference processing currently works in G1.
3001
3002 // Enable discovery in the STW reference processor
3003 if (g1_policy()->should_process_references()) {
3004 ref_processor_stw()->enable_discovery();
3005 } else {
3006 ref_processor_stw()->disable_discovery();
3007 }
3008
3009 {
3010 // We want to temporarily turn off discovery by the
3011 // CM ref processor, if necessary, and turn it back on
3012 // on again later if we do. Using a scoped
3013 // NoRefDiscovery object will do this.
3014 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3015
3016 // Forget the current alloc region (we might even choose it to be part
3017 // of the collection set!).
3018 _allocator->release_mutator_alloc_region();
3019
3020 // This timing is only used by the ergonomics to handle our pause target.
3021 // It is unclear why this should not include the full pause. We will
3022 // investigate this in CR 7178365.
3023 //
3024 // Preserving the old comment here if that helps the investigation:
3025 //
3026 // The elapsed time induced by the start time below deliberately elides
3027 // the possible verification above.
3028 double sample_start_time_sec = os::elapsedTime();
3029
3030 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3031
3032 if (collector_state()->during_initial_mark_pause()) {
3033 concurrent_mark()->checkpointRootsInitialPre();
3034 }
3035
3036 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3037
3038 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3039
3040 // Make sure the remembered sets are up to date. This needs to be
3041 // done before register_humongous_regions_with_cset(), because the
3042 // remembered sets are used there to choose eager reclaim candidates.
3043 // If the remembered sets are not up to date we might miss some
3044 // entries that need to be handled.
3045 g1_rem_set()->cleanupHRRS();
3046
3047 register_humongous_regions_with_cset();
3048
3049 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3050
3051 // We call this after finalize_cset() to
3052 // ensure that the CSet has been finalized.
3053 _cm->verify_no_cset_oops();
3054
3055 if (_hr_printer.is_active()) {
3056 G1PrintCollectionSetClosure cl(&_hr_printer);
3057 _collection_set.iterate(&cl);
3058 }
3059
3060 // Initialize the GC alloc regions.
3061 _allocator->init_gc_alloc_regions(evacuation_info);
3062
3063 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3064 pre_evacuate_collection_set();
3065
3066 // Actually do the work...
3067 evacuate_collection_set(evacuation_info, &per_thread_states);
3068
3069 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3070
3071 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3072 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3073
3074 eagerly_reclaim_humongous_regions();
3075
3076 record_obj_copy_mem_stats();
3077 _survivor_evac_stats.adjust_desired_plab_sz();
3078 _old_evac_stats.adjust_desired_plab_sz();
3079
3080 double start = os::elapsedTime();
3081 start_new_collection_set();
3082 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3083
3084 if (evacuation_failed()) {
3085 set_used(recalculate_used());
3086 if (_archive_allocator != NULL) {
3087 _archive_allocator->clear_used();
3088 }
3089 for (uint i = 0; i < ParallelGCThreads; i++) {
3090 if (_evacuation_failed_info_array[i].has_failed()) {
3091 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3092 }
3093 }
3094 } else {
3095 // The "used" of the the collection set have already been subtracted
3096 // when they were freed. Add in the bytes evacuated.
3097 increase_used(g1_policy()->bytes_copied_during_gc());
3098 }
3099
3100 if (collector_state()->during_initial_mark_pause()) {
3101 // We have to do this before we notify the CM threads that
3102 // they can start working to make sure that all the
3103 // appropriate initialization is done on the CM object.
3104 concurrent_mark()->checkpointRootsInitialPost();
3105 collector_state()->set_mark_in_progress(true);
3106 // Note that we don't actually trigger the CM thread at
3107 // this point. We do that later when we're sure that
3108 // the current thread has completed its logging output.
3109 }
3110
3111 allocate_dummy_regions();
3112
3113 _allocator->init_mutator_alloc_region();
3114
3115 {
3116 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3117 if (expand_bytes > 0) {
3118 size_t bytes_before = capacity();
3119 // No need for an ergo logging here,
3120 // expansion_amount() does this when it returns a value > 0.
3121 double expand_ms;
3122 if (!expand(expand_bytes, _workers, &expand_ms)) {
3123 // We failed to expand the heap. Cannot do anything about it.
3124 }
3125 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3126 }
3127 }
3128
3129 // We redo the verification but now wrt to the new CSet which
3130 // has just got initialized after the previous CSet was freed.
3131 _cm->verify_no_cset_oops();
3132
3133 // This timing is only used by the ergonomics to handle our pause target.
3134 // It is unclear why this should not include the full pause. We will
3135 // investigate this in CR 7178365.
3136 double sample_end_time_sec = os::elapsedTime();
3137 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3138 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3139 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3140
3141 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3142 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3143
3144 if (VerifyRememberedSets) {
3145 log_info(gc, verify)("[Verifying RemSets after GC]");
3146 VerifyRegionRemSetClosure v_cl;
3147 heap_region_iterate(&v_cl);
3148 }
3149
3150 _verifier->verify_after_gc();
3151 _verifier->check_bitmaps("GC End");
3152
3153 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3154 ref_processor_stw()->verify_no_references_recorded();
3155
3156 // CM reference discovery will be re-enabled if necessary.
3157 }
3158
3159 #ifdef TRACESPINNING
3160 ParallelTaskTerminator::print_termination_counts();
3161 #endif
3162
3163 gc_epilogue(false);
3164 }
3165
3166 // Print the remainder of the GC log output.
3167 if (evacuation_failed()) {
3168 log_info(gc)("To-space exhausted");
3169 }
3170
3171 g1_policy()->print_phases();
3172 heap_transition.print();
3173
3174 // It is not yet to safe to tell the concurrent mark to
3175 // start as we have some optional output below. We don't want the
3176 // output from the concurrent mark thread interfering with this
3177 // logging output either.
3178
3179 _hrm.verify_optional();
3180 _verifier->verify_region_sets_optional();
3181
3182 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3183 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3184
3185 print_heap_after_gc();
3186 print_heap_regions();
3187 trace_heap_after_gc(_gc_tracer_stw);
3188
3189 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3190 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3191 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3192 // before any GC notifications are raised.
3193 g1mm()->update_sizes();
3194
3195 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3196 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3197 _gc_timer_stw->register_gc_end();
3198 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3199 }
3200 // It should now be safe to tell the concurrent mark thread to start
3201 // without its logging output interfering with the logging output
3202 // that came from the pause.
3203
3204 if (should_start_conc_mark) {
3205 // CAUTION: after the doConcurrentMark() call below,
3206 // the concurrent marking thread(s) could be running
3207 // concurrently with us. Make sure that anything after
3208 // this point does not assume that we are the only GC thread
3209 // running. Note: of course, the actual marking work will
3210 // not start until the safepoint itself is released in
3211 // SuspendibleThreadSet::desynchronize().
3212 doConcurrentMark();
3213 }
3214
3215 return true;
3216 }
3217
3218 void G1CollectedHeap::remove_self_forwarding_pointers() {
3219 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3220 workers()->run_task(&rsfp_task);
3221 }
3222
3223 void G1CollectedHeap::restore_after_evac_failure() {
3224 double remove_self_forwards_start = os::elapsedTime();
3225
3226 remove_self_forwarding_pointers();
3227 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3228 _preserved_marks_set.restore(&task_executor);
3229
3230 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3231 }
3232
3233 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3234 if (!_evacuation_failed) {
3235 _evacuation_failed = true;
3236 }
3237
3238 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3239 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3240 }
3241
3242 bool G1ParEvacuateFollowersClosure::offer_termination() {
3243 G1ParScanThreadState* const pss = par_scan_state();
3244 start_term_time();
3245 const bool res = terminator()->offer_termination();
3246 end_term_time();
3247 return res;
3248 }
3249
3250 void G1ParEvacuateFollowersClosure::do_void() {
3251 G1ParScanThreadState* const pss = par_scan_state();
3252 pss->trim_queue();
3253 do {
3254 pss->steal_and_trim_queue(queues());
3255 } while (!offer_termination());
3256 }
3257
3258 class G1ParTask : public AbstractGangTask {
3259 protected:
3260 G1CollectedHeap* _g1h;
3261 G1ParScanThreadStateSet* _pss;
3262 RefToScanQueueSet* _queues;
3263 G1RootProcessor* _root_processor;
3264 ParallelTaskTerminator _terminator;
3265 uint _n_workers;
3266
3267 public:
3268 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3269 : AbstractGangTask("G1 collection"),
3270 _g1h(g1h),
3271 _pss(per_thread_states),
3272 _queues(task_queues),
3273 _root_processor(root_processor),
3274 _terminator(n_workers, _queues),
3275 _n_workers(n_workers)
3276 {}
3277
3278 void work(uint worker_id) {
3279 if (worker_id >= _n_workers) return; // no work needed this round
3280
3281 double start_sec = os::elapsedTime();
3282 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3283
3284 {
3285 ResourceMark rm;
3286 HandleMark hm;
3287
3288 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3289
3290 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3291 pss->set_ref_processor(rp);
3292
3293 double start_strong_roots_sec = os::elapsedTime();
3294
3295 _root_processor->evacuate_roots(pss->closures(), worker_id);
3296
3297 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3298 // treating the nmethods visited to act as roots for concurrent marking.
3299 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3300 // objects copied by the current evacuation.
3301 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3302 pss->closures()->weak_codeblobs(),
3303 worker_id);
3304
3305 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3306
3307 double term_sec = 0.0;
3308 size_t evac_term_attempts = 0;
3309 {
3310 double start = os::elapsedTime();
3311 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3312 evac.do_void();
3313
3314 evac_term_attempts = evac.term_attempts();
3315 term_sec = evac.term_time();
3316 double elapsed_sec = os::elapsedTime() - start;
3317 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3318 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3319 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3320 }
3321
3322 assert(pss->queue_is_empty(), "should be empty");
3323
3324 if (log_is_enabled(Debug, gc, task, stats)) {
3325 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3326 size_t lab_waste;
3327 size_t lab_undo_waste;
3328 pss->waste(lab_waste, lab_undo_waste);
3329 _g1h->print_termination_stats(worker_id,
3330 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3331 strong_roots_sec * 1000.0, /* strong roots time */
3332 term_sec * 1000.0, /* evac term time */
3333 evac_term_attempts, /* evac term attempts */
3334 lab_waste, /* alloc buffer waste */
3335 lab_undo_waste /* undo waste */
3336 );
3337 }
3338
3339 // Close the inner scope so that the ResourceMark and HandleMark
3340 // destructors are executed here and are included as part of the
3341 // "GC Worker Time".
3342 }
3343 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3344 }
3345 };
3346
3347 void G1CollectedHeap::print_termination_stats_hdr() {
3348 log_debug(gc, task, stats)("GC Termination Stats");
3349 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3350 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3351 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3352 }
3353
3354 void G1CollectedHeap::print_termination_stats(uint worker_id,
3355 double elapsed_ms,
3356 double strong_roots_ms,
3357 double term_ms,
3358 size_t term_attempts,
3359 size_t alloc_buffer_waste,
3360 size_t undo_waste) const {
3361 log_debug(gc, task, stats)
3362 ("%3d %9.2f %9.2f %6.2f "
3363 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3364 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3365 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3366 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3367 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3368 alloc_buffer_waste * HeapWordSize / K,
3369 undo_waste * HeapWordSize / K);
3370 }
3371
3372 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3373 private:
3374 BoolObjectClosure* _is_alive;
3375 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3376
3377 int _initial_string_table_size;
3378 int _initial_symbol_table_size;
3379
3380 bool _process_strings;
3381 int _strings_processed;
3382 int _strings_removed;
3383
3384 bool _process_symbols;
3385 int _symbols_processed;
3386 int _symbols_removed;
3387
3388 bool _process_string_dedup;
3389
3390 public:
3391 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3392 AbstractGangTask("String/Symbol Unlinking"),
3393 _is_alive(is_alive),
3394 _dedup_closure(is_alive, NULL, false),
3395 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3396 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3397 _process_string_dedup(process_string_dedup) {
3398
3399 _initial_string_table_size = StringTable::the_table()->table_size();
3400 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3401 if (process_strings) {
3402 StringTable::clear_parallel_claimed_index();
3403 }
3404 if (process_symbols) {
3405 SymbolTable::clear_parallel_claimed_index();
3406 }
3407 }
3408
3409 ~G1StringAndSymbolCleaningTask() {
3410 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3411 "claim value %d after unlink less than initial string table size %d",
3412 StringTable::parallel_claimed_index(), _initial_string_table_size);
3413 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3414 "claim value %d after unlink less than initial symbol table size %d",
3415 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3416
3417 log_info(gc, stringtable)(
3418 "Cleaned string and symbol table, "
3419 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3420 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3421 strings_processed(), strings_removed(),
3422 symbols_processed(), symbols_removed());
3423 }
3424
3425 void work(uint worker_id) {
3426 int strings_processed = 0;
3427 int strings_removed = 0;
3428 int symbols_processed = 0;
3429 int symbols_removed = 0;
3430 if (_process_strings) {
3431 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3432 Atomic::add(strings_processed, &_strings_processed);
3433 Atomic::add(strings_removed, &_strings_removed);
3434 }
3435 if (_process_symbols) {
3436 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3437 Atomic::add(symbols_processed, &_symbols_processed);
3438 Atomic::add(symbols_removed, &_symbols_removed);
3439 }
3440 if (_process_string_dedup) {
3441 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3442 }
3443 }
3444
3445 size_t strings_processed() const { return (size_t)_strings_processed; }
3446 size_t strings_removed() const { return (size_t)_strings_removed; }
3447
3448 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3449 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3450 };
3451
3452 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3453 private:
3454 static Monitor* _lock;
3455
3456 BoolObjectClosure* const _is_alive;
3457 const bool _unloading_occurred;
3458 const uint _num_workers;
3459
3460 // Variables used to claim nmethods.
3461 CompiledMethod* _first_nmethod;
3462 volatile CompiledMethod* _claimed_nmethod;
3463
3464 // The list of nmethods that need to be processed by the second pass.
3465 volatile CompiledMethod* _postponed_list;
3466 volatile uint _num_entered_barrier;
3467
3468 public:
3469 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3470 _is_alive(is_alive),
3471 _unloading_occurred(unloading_occurred),
3472 _num_workers(num_workers),
3473 _first_nmethod(NULL),
3474 _claimed_nmethod(NULL),
3475 _postponed_list(NULL),
3476 _num_entered_barrier(0)
3477 {
3478 CompiledMethod::increase_unloading_clock();
3479 // Get first alive nmethod
3480 CompiledMethodIterator iter = CompiledMethodIterator();
3481 if(iter.next_alive()) {
3482 _first_nmethod = iter.method();
3483 }
3484 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3485 }
3486
3487 ~G1CodeCacheUnloadingTask() {
3488 CodeCache::verify_clean_inline_caches();
3489
3490 CodeCache::set_needs_cache_clean(false);
3491 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3492
3493 CodeCache::verify_icholder_relocations();
3494 }
3495
3496 private:
3497 void add_to_postponed_list(CompiledMethod* nm) {
3498 CompiledMethod* old;
3499 do {
3500 old = (CompiledMethod*)_postponed_list;
3501 nm->set_unloading_next(old);
3502 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3503 }
3504
3505 void clean_nmethod(CompiledMethod* nm) {
3506 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3507
3508 if (postponed) {
3509 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3510 add_to_postponed_list(nm);
3511 }
3512
3513 // Mark that this thread has been cleaned/unloaded.
3514 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3515 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3516 }
3517
3518 void clean_nmethod_postponed(CompiledMethod* nm) {
3519 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3520 }
3521
3522 static const int MaxClaimNmethods = 16;
3523
3524 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3525 CompiledMethod* first;
3526 CompiledMethodIterator last;
3527
3528 do {
3529 *num_claimed_nmethods = 0;
3530
3531 first = (CompiledMethod*)_claimed_nmethod;
3532 last = CompiledMethodIterator(first);
3533
3534 if (first != NULL) {
3535
3536 for (int i = 0; i < MaxClaimNmethods; i++) {
3537 if (!last.next_alive()) {
3538 break;
3539 }
3540 claimed_nmethods[i] = last.method();
3541 (*num_claimed_nmethods)++;
3542 }
3543 }
3544
3545 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3546 }
3547
3548 CompiledMethod* claim_postponed_nmethod() {
3549 CompiledMethod* claim;
3550 CompiledMethod* next;
3551
3552 do {
3553 claim = (CompiledMethod*)_postponed_list;
3554 if (claim == NULL) {
3555 return NULL;
3556 }
3557
3558 next = claim->unloading_next();
3559
3560 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3561
3562 return claim;
3563 }
3564
3565 public:
3566 // Mark that we're done with the first pass of nmethod cleaning.
3567 void barrier_mark(uint worker_id) {
3568 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3569 _num_entered_barrier++;
3570 if (_num_entered_barrier == _num_workers) {
3571 ml.notify_all();
3572 }
3573 }
3574
3575 // See if we have to wait for the other workers to
3576 // finish their first-pass nmethod cleaning work.
3577 void barrier_wait(uint worker_id) {
3578 if (_num_entered_barrier < _num_workers) {
3579 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3580 while (_num_entered_barrier < _num_workers) {
3581 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3582 }
3583 }
3584 }
3585
3586 // Cleaning and unloading of nmethods. Some work has to be postponed
3587 // to the second pass, when we know which nmethods survive.
3588 void work_first_pass(uint worker_id) {
3589 // The first nmethods is claimed by the first worker.
3590 if (worker_id == 0 && _first_nmethod != NULL) {
3591 clean_nmethod(_first_nmethod);
3592 _first_nmethod = NULL;
3593 }
3594
3595 int num_claimed_nmethods;
3596 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3597
3598 while (true) {
3599 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3600
3601 if (num_claimed_nmethods == 0) {
3602 break;
3603 }
3604
3605 for (int i = 0; i < num_claimed_nmethods; i++) {
3606 clean_nmethod(claimed_nmethods[i]);
3607 }
3608 }
3609 }
3610
3611 void work_second_pass(uint worker_id) {
3612 CompiledMethod* nm;
3613 // Take care of postponed nmethods.
3614 while ((nm = claim_postponed_nmethod()) != NULL) {
3615 clean_nmethod_postponed(nm);
3616 }
3617 }
3618 };
3619
3620 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3621
3622 class G1KlassCleaningTask : public StackObj {
3623 BoolObjectClosure* _is_alive;
3624 volatile jint _clean_klass_tree_claimed;
3625 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3626
3627 public:
3628 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3629 _is_alive(is_alive),
3630 _clean_klass_tree_claimed(0),
3631 _klass_iterator() {
3632 }
3633
3634 private:
3635 bool claim_clean_klass_tree_task() {
3636 if (_clean_klass_tree_claimed) {
3637 return false;
3638 }
3639
3640 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3641 }
3642
3643 InstanceKlass* claim_next_klass() {
3644 Klass* klass;
3645 do {
3646 klass =_klass_iterator.next_klass();
3647 } while (klass != NULL && !klass->is_instance_klass());
3648
3649 // this can be null so don't call InstanceKlass::cast
3650 return static_cast<InstanceKlass*>(klass);
3651 }
3652
3653 public:
3654
3655 void clean_klass(InstanceKlass* ik) {
3656 ik->clean_weak_instanceklass_links(_is_alive);
3657 }
3658
3659 void work() {
3660 ResourceMark rm;
3661
3662 // One worker will clean the subklass/sibling klass tree.
3663 if (claim_clean_klass_tree_task()) {
3664 Klass::clean_subklass_tree(_is_alive);
3665 }
3666
3667 // All workers will help cleaning the classes,
3668 InstanceKlass* klass;
3669 while ((klass = claim_next_klass()) != NULL) {
3670 clean_klass(klass);
3671 }
3672 }
3673 };
3674
3675 class G1ResolvedMethodCleaningTask : public StackObj {
3676 BoolObjectClosure* _is_alive;
3677 volatile jint _resolved_method_task_claimed;
3678 public:
3679 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3680 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3681
3682 bool claim_resolved_method_task() {
3683 if (_resolved_method_task_claimed) {
3684 return false;
3685 }
3686 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3687 }
3688
3689 // These aren't big, one thread can do it all.
3690 void work() {
3691 if (claim_resolved_method_task()) {
3692 ResolvedMethodTable::unlink(_is_alive);
3693 }
3694 }
3695 };
3696
3697
3698 // To minimize the remark pause times, the tasks below are done in parallel.
3699 class G1ParallelCleaningTask : public AbstractGangTask {
3700 private:
3701 G1StringAndSymbolCleaningTask _string_symbol_task;
3702 G1CodeCacheUnloadingTask _code_cache_task;
3703 G1KlassCleaningTask _klass_cleaning_task;
3704 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3705
3706 public:
3707 // The constructor is run in the VMThread.
3708 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3709 AbstractGangTask("Parallel Cleaning"),
3710 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3711 _code_cache_task(num_workers, is_alive, unloading_occurred),
3712 _klass_cleaning_task(is_alive),
3713 _resolved_method_cleaning_task(is_alive) {
3714 }
3715
3716 // The parallel work done by all worker threads.
3717 void work(uint worker_id) {
3718 // Do first pass of code cache cleaning.
3719 _code_cache_task.work_first_pass(worker_id);
3720
3721 // Let the threads mark that the first pass is done.
3722 _code_cache_task.barrier_mark(worker_id);
3723
3724 // Clean the Strings and Symbols.
3725 _string_symbol_task.work(worker_id);
3726
3727 // Clean unreferenced things in the ResolvedMethodTable
3728 _resolved_method_cleaning_task.work();
3729
3730 // Wait for all workers to finish the first code cache cleaning pass.
3731 _code_cache_task.barrier_wait(worker_id);
3732
3733 // Do the second code cache cleaning work, which realize on
3734 // the liveness information gathered during the first pass.
3735 _code_cache_task.work_second_pass(worker_id);
3736
3737 // Clean all klasses that were not unloaded.
3738 _klass_cleaning_task.work();
3739 }
3740 };
3741
3742
3743 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3744 bool class_unloading_occurred) {
3745 uint n_workers = workers()->active_workers();
3746
3747 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3748 workers()->run_task(&g1_unlink_task);
3749 }
3750
3751 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3752 bool process_strings,
3753 bool process_symbols,
3754 bool process_string_dedup) {
3755 if (!process_strings && !process_symbols && !process_string_dedup) {
3756 // Nothing to clean.
3757 return;
3758 }
3759
3760 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3761 workers()->run_task(&g1_unlink_task);
3762
3763 }
3764
3765 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3766 private:
3767 DirtyCardQueueSet* _queue;
3768 G1CollectedHeap* _g1h;
3769 public:
3770 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3771 _queue(queue), _g1h(g1h) { }
3772
3773 virtual void work(uint worker_id) {
3774 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3775 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3776
3777 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3778 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3779
3780 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3781 }
3782 };
3783
3784 void G1CollectedHeap::redirty_logged_cards() {
3785 double redirty_logged_cards_start = os::elapsedTime();
3786
3787 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3788 dirty_card_queue_set().reset_for_par_iteration();
3789 workers()->run_task(&redirty_task);
3790
3791 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3792 dcq.merge_bufferlists(&dirty_card_queue_set());
3793 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3794
3795 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3796 }
3797
3798 // Weak Reference Processing support
3799
3800 // An always "is_alive" closure that is used to preserve referents.
3801 // If the object is non-null then it's alive. Used in the preservation
3802 // of referent objects that are pointed to by reference objects
3803 // discovered by the CM ref processor.
3804 class G1AlwaysAliveClosure: public BoolObjectClosure {
3805 G1CollectedHeap* _g1;
3806 public:
3807 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3808 bool do_object_b(oop p) {
3809 if (p != NULL) {
3810 return true;
3811 }
3812 return false;
3813 }
3814 };
3815
3816 bool G1STWIsAliveClosure::do_object_b(oop p) {
3817 // An object is reachable if it is outside the collection set,
3818 // or is inside and copied.
3819 return !_g1->is_in_cset(p) || p->is_forwarded();
3820 }
3821
3822 // Non Copying Keep Alive closure
3823 class G1KeepAliveClosure: public OopClosure {
3824 G1CollectedHeap* _g1;
3825 public:
3826 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3827 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3828 void do_oop(oop* p) {
3829 oop obj = *p;
3830 assert(obj != NULL, "the caller should have filtered out NULL values");
3831
3832 const InCSetState cset_state = _g1->in_cset_state(obj);
3833 if (!cset_state.is_in_cset_or_humongous()) {
3834 return;
3835 }
3836 if (cset_state.is_in_cset()) {
3837 assert( obj->is_forwarded(), "invariant" );
3838 *p = obj->forwardee();
3839 } else {
3840 assert(!obj->is_forwarded(), "invariant" );
3841 assert(cset_state.is_humongous(),
3842 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3843 _g1->set_humongous_is_live(obj);
3844 }
3845 }
3846 };
3847
3848 // Copying Keep Alive closure - can be called from both
3849 // serial and parallel code as long as different worker
3850 // threads utilize different G1ParScanThreadState instances
3851 // and different queues.
3852
3853 class G1CopyingKeepAliveClosure: public OopClosure {
3854 G1CollectedHeap* _g1h;
3855 OopClosure* _copy_non_heap_obj_cl;
3856 G1ParScanThreadState* _par_scan_state;
3857
3858 public:
3859 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3860 OopClosure* non_heap_obj_cl,
3861 G1ParScanThreadState* pss):
3862 _g1h(g1h),
3863 _copy_non_heap_obj_cl(non_heap_obj_cl),
3864 _par_scan_state(pss)
3865 {}
3866
3867 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3868 virtual void do_oop( oop* p) { do_oop_work(p); }
3869
3870 template <class T> void do_oop_work(T* p) {
3871 oop obj = oopDesc::load_decode_heap_oop(p);
3872
3873 if (_g1h->is_in_cset_or_humongous(obj)) {
3874 // If the referent object has been forwarded (either copied
3875 // to a new location or to itself in the event of an
3876 // evacuation failure) then we need to update the reference
3877 // field and, if both reference and referent are in the G1
3878 // heap, update the RSet for the referent.
3879 //
3880 // If the referent has not been forwarded then we have to keep
3881 // it alive by policy. Therefore we have copy the referent.
3882 //
3883 // If the reference field is in the G1 heap then we can push
3884 // on the PSS queue. When the queue is drained (after each
3885 // phase of reference processing) the object and it's followers
3886 // will be copied, the reference field set to point to the
3887 // new location, and the RSet updated. Otherwise we need to
3888 // use the the non-heap or metadata closures directly to copy
3889 // the referent object and update the pointer, while avoiding
3890 // updating the RSet.
3891
3892 if (_g1h->is_in_g1_reserved(p)) {
3893 _par_scan_state->push_on_queue(p);
3894 } else {
3895 assert(!Metaspace::contains((const void*)p),
3896 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3897 _copy_non_heap_obj_cl->do_oop(p);
3898 }
3899 }
3900 }
3901 };
3902
3903 // Serial drain queue closure. Called as the 'complete_gc'
3904 // closure for each discovered list in some of the
3905 // reference processing phases.
3906
3907 class G1STWDrainQueueClosure: public VoidClosure {
3908 protected:
3909 G1CollectedHeap* _g1h;
3910 G1ParScanThreadState* _par_scan_state;
3911
3912 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3913
3914 public:
3915 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3916 _g1h(g1h),
3917 _par_scan_state(pss)
3918 { }
3919
3920 void do_void() {
3921 G1ParScanThreadState* const pss = par_scan_state();
3922 pss->trim_queue();
3923 }
3924 };
3925
3926 // Parallel Reference Processing closures
3927
3928 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3929 // processing during G1 evacuation pauses.
3930
3931 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3932 private:
3933 G1CollectedHeap* _g1h;
3934 G1ParScanThreadStateSet* _pss;
3935 RefToScanQueueSet* _queues;
3936 WorkGang* _workers;
3937 uint _active_workers;
3938
3939 public:
3940 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3941 G1ParScanThreadStateSet* per_thread_states,
3942 WorkGang* workers,
3943 RefToScanQueueSet *task_queues,
3944 uint n_workers) :
3945 _g1h(g1h),
3946 _pss(per_thread_states),
3947 _queues(task_queues),
3948 _workers(workers),
3949 _active_workers(n_workers)
3950 {
3951 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3952 }
3953
3954 // Executes the given task using concurrent marking worker threads.
3955 virtual void execute(ProcessTask& task);
3956 virtual void execute(EnqueueTask& task);
3957 };
3958
3959 // Gang task for possibly parallel reference processing
3960
3961 class G1STWRefProcTaskProxy: public AbstractGangTask {
3962 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3963 ProcessTask& _proc_task;
3964 G1CollectedHeap* _g1h;
3965 G1ParScanThreadStateSet* _pss;
3966 RefToScanQueueSet* _task_queues;
3967 ParallelTaskTerminator* _terminator;
3968
3969 public:
3970 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3971 G1CollectedHeap* g1h,
3972 G1ParScanThreadStateSet* per_thread_states,
3973 RefToScanQueueSet *task_queues,
3974 ParallelTaskTerminator* terminator) :
3975 AbstractGangTask("Process reference objects in parallel"),
3976 _proc_task(proc_task),
3977 _g1h(g1h),
3978 _pss(per_thread_states),
3979 _task_queues(task_queues),
3980 _terminator(terminator)
3981 {}
3982
3983 virtual void work(uint worker_id) {
3984 // The reference processing task executed by a single worker.
3985 ResourceMark rm;
3986 HandleMark hm;
3987
3988 G1STWIsAliveClosure is_alive(_g1h);
3989
3990 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3991 pss->set_ref_processor(NULL);
3992
3993 // Keep alive closure.
3994 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3995
3996 // Complete GC closure
3997 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3998
3999 // Call the reference processing task's work routine.
4000 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4001
4002 // Note we cannot assert that the refs array is empty here as not all
4003 // of the processing tasks (specifically phase2 - pp2_work) execute
4004 // the complete_gc closure (which ordinarily would drain the queue) so
4005 // the queue may not be empty.
4006 }
4007 };
4008
4009 // Driver routine for parallel reference processing.
4010 // Creates an instance of the ref processing gang
4011 // task and has the worker threads execute it.
4012 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4013 assert(_workers != NULL, "Need parallel worker threads.");
4014
4015 ParallelTaskTerminator terminator(_active_workers, _queues);
4016 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4017
4018 _workers->run_task(&proc_task_proxy);
4019 }
4020
4021 // Gang task for parallel reference enqueueing.
4022
4023 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4024 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4025 EnqueueTask& _enq_task;
4026
4027 public:
4028 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4029 AbstractGangTask("Enqueue reference objects in parallel"),
4030 _enq_task(enq_task)
4031 { }
4032
4033 virtual void work(uint worker_id) {
4034 _enq_task.work(worker_id);
4035 }
4036 };
4037
4038 // Driver routine for parallel reference enqueueing.
4039 // Creates an instance of the ref enqueueing gang
4040 // task and has the worker threads execute it.
4041
4042 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4043 assert(_workers != NULL, "Need parallel worker threads.");
4044
4045 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4046
4047 _workers->run_task(&enq_task_proxy);
4048 }
4049
4050 // End of weak reference support closures
4051
4052 // Abstract task used to preserve (i.e. copy) any referent objects
4053 // that are in the collection set and are pointed to by reference
4054 // objects discovered by the CM ref processor.
4055
4056 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4057 protected:
4058 G1CollectedHeap* _g1h;
4059 G1ParScanThreadStateSet* _pss;
4060 RefToScanQueueSet* _queues;
4061 ParallelTaskTerminator _terminator;
4062 uint _n_workers;
4063
4064 public:
4065 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4066 AbstractGangTask("ParPreserveCMReferents"),
4067 _g1h(g1h),
4068 _pss(per_thread_states),
4069 _queues(task_queues),
4070 _terminator(workers, _queues),
4071 _n_workers(workers)
4072 {
4073 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4074 }
4075
4076 void work(uint worker_id) {
4077 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4078
4079 ResourceMark rm;
4080 HandleMark hm;
4081
4082 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4083 pss->set_ref_processor(NULL);
4084 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4085
4086 // Is alive closure
4087 G1AlwaysAliveClosure always_alive(_g1h);
4088
4089 // Copying keep alive closure. Applied to referent objects that need
4090 // to be copied.
4091 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4092
4093 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4094
4095 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4096 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4097
4098 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4099 // So this must be true - but assert just in case someone decides to
4100 // change the worker ids.
4101 assert(worker_id < limit, "sanity");
4102 assert(!rp->discovery_is_atomic(), "check this code");
4103
4104 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4105 for (uint idx = worker_id; idx < limit; idx += stride) {
4106 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4107
4108 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4109 while (iter.has_next()) {
4110 // Since discovery is not atomic for the CM ref processor, we
4111 // can see some null referent objects.
4112 iter.load_ptrs(DEBUG_ONLY(true));
4113 oop ref = iter.obj();
4114
4115 // This will filter nulls.
4116 if (iter.is_referent_alive()) {
4117 iter.make_referent_alive();
4118 }
4119 iter.move_to_next();
4120 }
4121 }
4122
4123 // Drain the queue - which may cause stealing
4124 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4125 drain_queue.do_void();
4126 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4127 assert(pss->queue_is_empty(), "should be");
4128 }
4129 };
4130
4131 void G1CollectedHeap::process_weak_jni_handles() {
4132 double ref_proc_start = os::elapsedTime();
4133
4134 G1STWIsAliveClosure is_alive(this);
4135 G1KeepAliveClosure keep_alive(this);
4136 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4137
4138 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4139 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4140 }
4141
4142 void G1CollectedHeap::process_heap_monitoring() {
4143 log_develop_trace(gc, ref)("Heap Sampler: heap monitoring processing");
4144 G1STWIsAliveClosure is_alive(this);
4145 G1KeepAliveClosure keep_alive(this);
4146 HeapMonitoring::weak_oops_do(&is_alive, &keep_alive);
4147 }
4148
4149 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4150 // Any reference objects, in the collection set, that were 'discovered'
4151 // by the CM ref processor should have already been copied (either by
4152 // applying the external root copy closure to the discovered lists, or
4153 // by following an RSet entry).
4154 //
4155 // But some of the referents, that are in the collection set, that these
4156 // reference objects point to may not have been copied: the STW ref
4157 // processor would have seen that the reference object had already
4158 // been 'discovered' and would have skipped discovering the reference,
4159 // but would not have treated the reference object as a regular oop.
4160 // As a result the copy closure would not have been applied to the
4161 // referent object.
4162 //
4163 // We need to explicitly copy these referent objects - the references
4164 // will be processed at the end of remarking.
4165 //
4166 // We also need to do this copying before we process the reference
4167 // objects discovered by the STW ref processor in case one of these
4168 // referents points to another object which is also referenced by an
4169 // object discovered by the STW ref processor.
4170 double preserve_cm_referents_time = 0.0;
4171
4172 // To avoid spawning task when there is no work to do, check that
4173 // a concurrent cycle is active and that some references have been
4174 // discovered.
4175 if (concurrent_mark()->cmThread()->during_cycle() &&
4176 ref_processor_cm()->has_discovered_references()) {
4177 double preserve_cm_referents_start = os::elapsedTime();
4178 uint no_of_gc_workers = workers()->active_workers();
4179 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4180 per_thread_states,
4181 no_of_gc_workers,
4182 _task_queues);
4183 workers()->run_task(&keep_cm_referents);
4184 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4185 }
4186
4187 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4188 }
4189
4190 // Weak Reference processing during an evacuation pause (part 1).
4191 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4192 double ref_proc_start = os::elapsedTime();
4193
4194 ReferenceProcessor* rp = _ref_processor_stw;
4195 assert(rp->discovery_enabled(), "should have been enabled");
4196
4197 // Closure to test whether a referent is alive.
4198 G1STWIsAliveClosure is_alive(this);
4199
4200 // Even when parallel reference processing is enabled, the processing
4201 // of JNI refs is serial and performed serially by the current thread
4202 // rather than by a worker. The following PSS will be used for processing
4203 // JNI refs.
4204
4205 // Use only a single queue for this PSS.
4206 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4207 pss->set_ref_processor(NULL);
4208 assert(pss->queue_is_empty(), "pre-condition");
4209
4210 // Keep alive closure.
4211 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4212
4213 // Serial Complete GC closure
4214 G1STWDrainQueueClosure drain_queue(this, pss);
4215
4216 // Setup the soft refs policy...
4217 rp->setup_policy(false);
4218
4219 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4220
4221 ReferenceProcessorStats stats;
4222 if (!rp->processing_is_mt()) {
4223 // Serial reference processing...
4224 stats = rp->process_discovered_references(&is_alive,
4225 &keep_alive,
4226 &drain_queue,
4227 NULL,
4228 pt);
4229 } else {
4230 uint no_of_gc_workers = workers()->active_workers();
4231
4232 // Parallel reference processing
4233 assert(no_of_gc_workers <= rp->max_num_q(),
4234 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4235 no_of_gc_workers, rp->max_num_q());
4236
4237 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4238 stats = rp->process_discovered_references(&is_alive,
4239 &keep_alive,
4240 &drain_queue,
4241 &par_task_executor,
4242 pt);
4243 }
4244
4245 _gc_tracer_stw->report_gc_reference_stats(stats);
4246
4247 // We have completed copying any necessary live referent objects.
4248 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4249
4250 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4251 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4252 }
4253
4254 // Weak Reference processing during an evacuation pause (part 2).
4255 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4256 double ref_enq_start = os::elapsedTime();
4257
4258 ReferenceProcessor* rp = _ref_processor_stw;
4259 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4260
4261 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4262
4263 // Now enqueue any remaining on the discovered lists on to
4264 // the pending list.
4265 if (!rp->processing_is_mt()) {
4266 // Serial reference processing...
4267 rp->enqueue_discovered_references(NULL, pt);
4268 } else {
4269 // Parallel reference enqueueing
4270
4271 uint n_workers = workers()->active_workers();
4272
4273 assert(n_workers <= rp->max_num_q(),
4274 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4275 n_workers, rp->max_num_q());
4276
4277 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4278 rp->enqueue_discovered_references(&par_task_executor, pt);
4279 }
4280
4281 rp->verify_no_references_recorded();
4282 assert(!rp->discovery_enabled(), "should have been disabled");
4283
4284 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4285 // ensure that it is marked in the bitmap for concurrent marking to discover.
4286 if (collector_state()->during_initial_mark_pause()) {
4287 oop pll_head = Universe::reference_pending_list();
4288 if (pll_head != NULL) {
4289 _cm->mark_in_next_bitmap(pll_head);
4290 }
4291 }
4292
4293 // FIXME
4294 // CM's reference processing also cleans up the string and symbol tables.
4295 // Should we do that here also? We could, but it is a serial operation
4296 // and could significantly increase the pause time.
4297
4298 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4299 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4300 }
4301
4302 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4303 double merge_pss_time_start = os::elapsedTime();
4304 per_thread_states->flush();
4305 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4306 }
4307
4308 void G1CollectedHeap::pre_evacuate_collection_set() {
4309 _expand_heap_after_alloc_failure = true;
4310 _evacuation_failed = false;
4311
4312 // Disable the hot card cache.
4313 _hot_card_cache->reset_hot_cache_claimed_index();
4314 _hot_card_cache->set_use_cache(false);
4315
4316 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4317 _preserved_marks_set.assert_empty();
4318
4319 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4320
4321 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4322 if (collector_state()->during_initial_mark_pause()) {
4323 double start_clear_claimed_marks = os::elapsedTime();
4324
4325 ClassLoaderDataGraph::clear_claimed_marks();
4326
4327 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4328 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4329 }
4330 }
4331
4332 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4333 // Should G1EvacuationFailureALot be in effect for this GC?
4334 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4335
4336 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4337
4338 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4339
4340 double start_par_time_sec = os::elapsedTime();
4341 double end_par_time_sec;
4342
4343 {
4344 const uint n_workers = workers()->active_workers();
4345 G1RootProcessor root_processor(this, n_workers);
4346 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4347
4348 print_termination_stats_hdr();
4349
4350 workers()->run_task(&g1_par_task);
4351 end_par_time_sec = os::elapsedTime();
4352
4353 // Closing the inner scope will execute the destructor
4354 // for the G1RootProcessor object. We record the current
4355 // elapsed time before closing the scope so that time
4356 // taken for the destructor is NOT included in the
4357 // reported parallel time.
4358 }
4359
4360 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4361 phase_times->record_par_time(par_time_ms);
4362
4363 double code_root_fixup_time_ms =
4364 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4365 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4366 }
4367
4368 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4369 // Process any discovered reference objects - we have
4370 // to do this _before_ we retire the GC alloc regions
4371 // as we may have to copy some 'reachable' referent
4372 // objects (and their reachable sub-graphs) that were
4373 // not copied during the pause.
4374 if (g1_policy()->should_process_references()) {
4375 preserve_cm_referents(per_thread_states);
4376 process_discovered_references(per_thread_states);
4377 } else {
4378 ref_processor_stw()->verify_no_references_recorded();
4379 process_weak_jni_handles();
4380 process_heap_monitoring();
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 CollectedHeap::register_nmethod(nm);
5337
5338 guarantee(nm != NULL, "sanity");
5339 RegisterNMethodOopClosure reg_cl(this, nm);
5340 nm->oops_do(®_cl);
5341 }
5342
5343 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5344 CollectedHeap::unregister_nmethod(nm);
5345
5346 guarantee(nm != NULL, "sanity");
5347 UnregisterNMethodOopClosure reg_cl(this, nm);
5348 nm->oops_do(®_cl, true);
5349 }
5350
5351 void G1CollectedHeap::purge_code_root_memory() {
5352 double purge_start = os::elapsedTime();
5353 G1CodeRootSet::purge();
5354 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5355 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5356 }
5357
5358 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5359 G1CollectedHeap* _g1h;
5360
5361 public:
5362 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5363 _g1h(g1h) {}
5364
5365 void do_code_blob(CodeBlob* cb) {
5366 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5367 if (nm == NULL) {
5368 return;
5369 }
5370
5371 if (ScavengeRootsInCode) {
5372 _g1h->register_nmethod(nm);
5373 }
5374 }
5375 };
5376
5377 void G1CollectedHeap::rebuild_strong_code_roots() {
5378 RebuildStrongCodeRootClosure blob_cl(this);
5379 CodeCache::blobs_do(&blob_cl);
5380 }