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/concurrentMarkThread.inline.hpp"
33 #include "gc/g1/g1Allocator.inline.hpp"
34 #include "gc/g1/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1FullGCScope.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1YCTypes.hpp"
58 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
59 #include "gc/g1/heapRegion.inline.hpp"
60 #include "gc/g1/heapRegionRemSet.hpp"
61 #include "gc/g1/heapRegionSet.inline.hpp"
62 #include "gc/g1/vm_operations_g1.hpp"
63 #include "gc/shared/gcHeapSummary.hpp"
64 #include "gc/shared/gcId.hpp"
65 #include "gc/shared/gcLocker.inline.hpp"
66 #include "gc/shared/gcTimer.hpp"
67 #include "gc/shared/gcTrace.hpp"
68 #include "gc/shared/gcTraceTime.inline.hpp"
69 #include "gc/shared/generationSpec.hpp"
70 #include "gc/shared/isGCActiveMark.hpp"
71 #include "gc/shared/preservedMarks.inline.hpp"
72 #include "gc/shared/suspendibleThreadSet.hpp"
73 #include "gc/shared/referenceProcessor.inline.hpp"
74 #include "gc/shared/taskqueue.inline.hpp"
75 #include "gc/shared/weakProcessor.hpp"
76 #include "logging/log.hpp"
77 #include "memory/allocation.hpp"
78 #include "memory/iterator.hpp"
79 #include "memory/resourceArea.hpp"
80 #include "oops/oop.inline.hpp"
81 #include "prims/resolvedMethodTable.hpp"
82 #include "runtime/atomic.hpp"
83 #include "runtime/init.hpp"
84 #include "runtime/orderAccess.inline.hpp"
85 #include "runtime/vmThread.hpp"
86 #include "services/memoryManager.hpp"
87 #include "utilities/align.hpp"
88 #include "utilities/globalDefinitions.hpp"
89 #include "utilities/stack.inline.hpp"
90
91 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
92
93 // INVARIANTS/NOTES
94 //
95 // All allocation activity covered by the G1CollectedHeap interface is
96 // serialized by acquiring the HeapLock. This happens in mem_allocate
97 // and allocate_new_tlab, which are the "entry" points to the
98 // allocation code from the rest of the JVM. (Note that this does not
99 // apply to TLAB allocation, which is not part of this interface: it
100 // is done by clients of this interface.)
101
102 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
103 private:
104 size_t _num_dirtied;
105 G1CollectedHeap* _g1h;
106 G1SATBCardTableLoggingModRefBS* _g1_bs;
107
108 HeapRegion* region_for_card(jbyte* card_ptr) const {
109 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
110 }
111
112 bool will_become_free(HeapRegion* hr) const {
113 // A region will be freed by free_collection_set if the region is in the
114 // collection set and has not had an evacuation failure.
115 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
116 }
117
118 public:
119 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
120 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
121
122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
123 HeapRegion* hr = region_for_card(card_ptr);
124
125 // Should only dirty cards in regions that won't be freed.
126 if (!will_become_free(hr)) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_dirtied++;
129 }
130
131 return true;
132 }
133
134 size_t num_dirtied() const { return _num_dirtied; }
135 };
136
137
138 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
139 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
140 }
141
142 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
143 // The from card cache is not the memory that is actually committed. So we cannot
144 // take advantage of the zero_filled parameter.
145 reset_from_card_cache(start_idx, num_regions);
146 }
147
148
149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
150 MemRegion mr) {
151 return new HeapRegion(hrs_index, bot(), mr);
152 }
153
154 // Private methods.
155
156 HeapRegion*
157 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
158 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
159 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
160 if (!_secondary_free_list.is_empty()) {
161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
162 "secondary_free_list has %u entries",
163 _secondary_free_list.length());
164 // It looks as if there are free regions available on the
165 // secondary_free_list. Let's move them to the free_list and try
166 // again to allocate from it.
167 append_secondary_free_list();
168
169 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
170 "empty we should have moved at least one entry to the free_list");
171 HeapRegion* res = _hrm.allocate_free_region(is_old);
172 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
173 "allocated " HR_FORMAT " from secondary_free_list",
174 HR_FORMAT_PARAMS(res));
175 return res;
176 }
177
178 // Wait here until we get notified either when (a) there are no
179 // more free regions coming or (b) some regions have been moved on
180 // the secondary_free_list.
181 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
182 }
183
184 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
185 "could not allocate from secondary_free_list");
186 return NULL;
187 }
188
189 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
190 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
191 "the only time we use this to allocate a humongous region is "
192 "when we are allocating a single humongous region");
193
194 HeapRegion* res;
195 if (G1StressConcRegionFreeing) {
196 if (!_secondary_free_list.is_empty()) {
197 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
198 "forced to look at the secondary_free_list");
199 res = new_region_try_secondary_free_list(is_old);
200 if (res != NULL) {
201 return res;
202 }
203 }
204 }
205
206 res = _hrm.allocate_free_region(is_old);
207
208 if (res == NULL) {
209 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
210 "res == NULL, trying the secondary_free_list");
211 res = new_region_try_secondary_free_list(is_old);
212 }
213 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
214 // Currently, only attempts to allocate GC alloc regions set
215 // do_expand to true. So, we should only reach here during a
216 // safepoint. If this assumption changes we might have to
217 // reconsider the use of _expand_heap_after_alloc_failure.
218 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
219
220 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
221 word_size * HeapWordSize);
222
223 if (expand(word_size * HeapWordSize)) {
224 // Given that expand() succeeded in expanding the heap, and we
225 // always expand the heap by an amount aligned to the heap
226 // region size, the free list should in theory not be empty.
227 // In either case allocate_free_region() will check for NULL.
228 res = _hrm.allocate_free_region(is_old);
229 } else {
230 _expand_heap_after_alloc_failure = false;
231 }
232 }
233 return res;
234 }
235
236 HeapWord*
237 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
238 uint num_regions,
239 size_t word_size,
240 AllocationContext_t context) {
241 assert(first != G1_NO_HRM_INDEX, "pre-condition");
242 assert(is_humongous(word_size), "word_size should be humongous");
243 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
244
245 // Index of last region in the series.
246 uint last = first + num_regions - 1;
247
248 // We need to initialize the region(s) we just discovered. This is
249 // a bit tricky given that it can happen concurrently with
250 // refinement threads refining cards on these regions and
251 // potentially wanting to refine the BOT as they are scanning
252 // those cards (this can happen shortly after a cleanup; see CR
253 // 6991377). So we have to set up the region(s) carefully and in
254 // a specific order.
255
256 // The word size sum of all the regions we will allocate.
257 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
258 assert(word_size <= word_size_sum, "sanity");
259
260 // This will be the "starts humongous" region.
261 HeapRegion* first_hr = region_at(first);
262 // The header of the new object will be placed at the bottom of
263 // the first region.
264 HeapWord* new_obj = first_hr->bottom();
265 // This will be the new top of the new object.
266 HeapWord* obj_top = new_obj + word_size;
267
268 // First, we need to zero the header of the space that we will be
269 // allocating. When we update top further down, some refinement
270 // threads might try to scan the region. By zeroing the header we
271 // ensure that any thread that will try to scan the region will
272 // come across the zero klass word and bail out.
273 //
274 // NOTE: It would not have been correct to have used
275 // CollectedHeap::fill_with_object() and make the space look like
276 // an int array. The thread that is doing the allocation will
277 // later update the object header to a potentially different array
278 // type and, for a very short period of time, the klass and length
279 // fields will be inconsistent. This could cause a refinement
280 // thread to calculate the object size incorrectly.
281 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
282
283 // Next, pad out the unused tail of the last region with filler
284 // objects, for improved usage accounting.
285 // How many words we use for filler objects.
286 size_t word_fill_size = word_size_sum - word_size;
287
288 // How many words memory we "waste" which cannot hold a filler object.
289 size_t words_not_fillable = 0;
290
291 if (word_fill_size >= min_fill_size()) {
292 fill_with_objects(obj_top, word_fill_size);
293 } else if (word_fill_size > 0) {
294 // We have space to fill, but we cannot fit an object there.
295 words_not_fillable = word_fill_size;
296 word_fill_size = 0;
297 }
298
299 // We will set up the first region as "starts humongous". This
300 // will also update the BOT covering all the regions to reflect
301 // that there is a single object that starts at the bottom of the
302 // first region.
303 first_hr->set_starts_humongous(obj_top, word_fill_size);
304 first_hr->set_allocation_context(context);
305 // Then, if there are any, we will set up the "continues
306 // humongous" regions.
307 HeapRegion* hr = NULL;
308 for (uint i = first + 1; i <= last; ++i) {
309 hr = region_at(i);
310 hr->set_continues_humongous(first_hr);
311 hr->set_allocation_context(context);
312 }
313
314 // Up to this point no concurrent thread would have been able to
315 // do any scanning on any region in this series. All the top
316 // fields still point to bottom, so the intersection between
317 // [bottom,top] and [card_start,card_end] will be empty. Before we
318 // update the top fields, we'll do a storestore to make sure that
319 // no thread sees the update to top before the zeroing of the
320 // object header and the BOT initialization.
321 OrderAccess::storestore();
322
323 // Now, we will update the top fields of the "continues humongous"
324 // regions except the last one.
325 for (uint i = first; i < last; ++i) {
326 hr = region_at(i);
327 hr->set_top(hr->end());
328 }
329
330 hr = region_at(last);
331 // If we cannot fit a filler object, we must set top to the end
332 // of the humongous object, otherwise we cannot iterate the heap
333 // and the BOT will not be complete.
334 hr->set_top(hr->end() - words_not_fillable);
335
336 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
337 "obj_top should be in last region");
338
339 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
340
341 assert(words_not_fillable == 0 ||
342 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
343 "Miscalculation in humongous allocation");
344
345 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
346
347 for (uint i = first; i <= last; ++i) {
348 hr = region_at(i);
349 _humongous_set.add(hr);
350 _hr_printer.alloc(hr);
351 }
352
353 return new_obj;
354 }
355
356 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
357 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
358 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
359 }
360
361 // If could fit into free regions w/o expansion, try.
362 // Otherwise, if can expand, do so.
363 // Otherwise, if using ex regions might help, try with ex given back.
364 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
365 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
366
367 _verifier->verify_region_sets_optional();
368
369 uint first = G1_NO_HRM_INDEX;
370 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
371
372 if (obj_regions == 1) {
373 // Only one region to allocate, try to use a fast path by directly allocating
374 // from the free lists. Do not try to expand here, we will potentially do that
375 // later.
376 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
377 if (hr != NULL) {
378 first = hr->hrm_index();
379 }
380 } else {
381 // We can't allocate humongous regions spanning more than one region while
382 // cleanupComplete() is running, since some of the regions we find to be
383 // empty might not yet be added to the free list. It is not straightforward
384 // to know in which list they are on so that we can remove them. We only
385 // need to do this if we need to allocate more than one region to satisfy the
386 // current humongous allocation request. If we are only allocating one region
387 // we use the one-region region allocation code (see above), that already
388 // potentially waits for regions from the secondary free list.
389 wait_while_free_regions_coming();
390 append_secondary_free_list_if_not_empty_with_lock();
391
392 // Policy: Try only empty regions (i.e. already committed first). Maybe we
393 // are lucky enough to find some.
394 first = _hrm.find_contiguous_only_empty(obj_regions);
395 if (first != G1_NO_HRM_INDEX) {
396 _hrm.allocate_free_regions_starting_at(first, obj_regions);
397 }
398 }
399
400 if (first == G1_NO_HRM_INDEX) {
401 // Policy: We could not find enough regions for the humongous object in the
402 // free list. Look through the heap to find a mix of free and uncommitted regions.
403 // If so, try expansion.
404 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
405 if (first != G1_NO_HRM_INDEX) {
406 // We found something. Make sure these regions are committed, i.e. expand
407 // the heap. Alternatively we could do a defragmentation GC.
408 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
409 word_size * HeapWordSize);
410
411 _hrm.expand_at(first, obj_regions, workers());
412 g1_policy()->record_new_heap_size(num_regions());
413
414 #ifdef ASSERT
415 for (uint i = first; i < first + obj_regions; ++i) {
416 HeapRegion* hr = region_at(i);
417 assert(hr->is_free(), "sanity");
418 assert(hr->is_empty(), "sanity");
419 assert(is_on_master_free_list(hr), "sanity");
420 }
421 #endif
422 _hrm.allocate_free_regions_starting_at(first, obj_regions);
423 } else {
424 // Policy: Potentially trigger a defragmentation GC.
425 }
426 }
427
428 HeapWord* result = NULL;
429 if (first != G1_NO_HRM_INDEX) {
430 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
431 word_size, context);
432 assert(result != NULL, "it should always return a valid result");
433
434 // A successful humongous object allocation changes the used space
435 // information of the old generation so we need to recalculate the
436 // sizes and update the jstat counters here.
437 g1mm()->update_sizes();
438 }
439
440 _verifier->verify_region_sets_optional();
441
442 return result;
443 }
444
445 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
446 assert_heap_not_locked_and_not_at_safepoint();
447 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
448
449 uint dummy_gc_count_before;
450 uint dummy_gclocker_retry_count = 0;
451 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
452 }
453
454 HeapWord*
455 G1CollectedHeap::mem_allocate(size_t word_size,
456 bool* gc_overhead_limit_was_exceeded) {
457 assert_heap_not_locked_and_not_at_safepoint();
458
459 // Loop until the allocation is satisfied, or unsatisfied after GC.
460 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
461 uint gc_count_before;
462
463 HeapWord* result = NULL;
464 if (!is_humongous(word_size)) {
465 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
466 } else {
467 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
468 }
469 if (result != NULL) {
470 return result;
471 }
472
473 // Create the garbage collection operation...
474 VM_G1CollectForAllocation op(gc_count_before, word_size);
475 op.set_allocation_context(AllocationContext::current());
476
477 // ...and get the VM thread to execute it.
478 VMThread::execute(&op);
479
480 if (op.prologue_succeeded() && op.pause_succeeded()) {
481 // If the operation was successful we'll return the result even
482 // if it is NULL. If the allocation attempt failed immediately
483 // after a Full GC, it's unlikely we'll be able to allocate now.
484 HeapWord* result = op.result();
485 if (result != NULL && !is_humongous(word_size)) {
486 // Allocations that take place on VM operations do not do any
487 // card dirtying and we have to do it here. We only have to do
488 // this for non-humongous allocations, though.
489 dirty_young_block(result, word_size);
490 }
491 return result;
492 } else {
493 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
494 return NULL;
495 }
496 assert(op.result() == NULL,
497 "the result should be NULL if the VM op did not succeed");
498 }
499
500 // Give a warning if we seem to be looping forever.
501 if ((QueuedAllocationWarningCount > 0) &&
502 (try_count % QueuedAllocationWarningCount == 0)) {
503 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
504 }
505 }
506
507 ShouldNotReachHere();
508 return NULL;
509 }
510
511 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
512 AllocationContext_t context,
513 uint* gc_count_before_ret,
514 uint* gclocker_retry_count_ret) {
515 // Make sure you read the note in attempt_allocation_humongous().
516
517 assert_heap_not_locked_and_not_at_safepoint();
518 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
519 "be called for humongous allocation requests");
520
521 // We should only get here after the first-level allocation attempt
522 // (attempt_allocation()) failed to allocate.
523
524 // We will loop until a) we manage to successfully perform the
525 // allocation or b) we successfully schedule a collection which
526 // fails to perform the allocation. b) is the only case when we'll
527 // return NULL.
528 HeapWord* result = NULL;
529 for (int try_count = 1; /* we'll return */; try_count += 1) {
530 bool should_try_gc;
531 uint gc_count_before;
532
533 {
534 MutexLockerEx x(Heap_lock);
535 result = _allocator->attempt_allocation_locked(word_size, context);
536 if (result != NULL) {
537 return result;
538 }
539
540 if (GCLocker::is_active_and_needs_gc()) {
541 if (g1_policy()->can_expand_young_list()) {
542 // No need for an ergo verbose message here,
543 // can_expand_young_list() does this when it returns true.
544 result = _allocator->attempt_allocation_force(word_size, context);
545 if (result != NULL) {
546 return result;
547 }
548 }
549 should_try_gc = false;
550 } else {
551 // The GCLocker may not be active but the GCLocker initiated
552 // GC may not yet have been performed (GCLocker::needs_gc()
553 // returns true). In this case we do not try this GC and
554 // wait until the GCLocker initiated GC is performed, and
555 // then retry the allocation.
556 if (GCLocker::needs_gc()) {
557 should_try_gc = false;
558 } else {
559 // Read the GC count while still holding the Heap_lock.
560 gc_count_before = total_collections();
561 should_try_gc = true;
562 }
563 }
564 }
565
566 if (should_try_gc) {
567 bool succeeded;
568 result = do_collection_pause(word_size, gc_count_before, &succeeded,
569 GCCause::_g1_inc_collection_pause);
570 if (result != NULL) {
571 assert(succeeded, "only way to get back a non-NULL result");
572 return result;
573 }
574
575 if (succeeded) {
576 // If we get here we successfully scheduled a collection which
577 // failed to allocate. No point in trying to allocate
578 // further. We'll just return NULL.
579 MutexLockerEx x(Heap_lock);
580 *gc_count_before_ret = total_collections();
581 return NULL;
582 }
583 } else {
584 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
585 MutexLockerEx x(Heap_lock);
586 *gc_count_before_ret = total_collections();
587 return NULL;
588 }
589 // The GCLocker is either active or the GCLocker initiated
590 // GC has not yet been performed. Stall until it is and
591 // then retry the allocation.
592 GCLocker::stall_until_clear();
593 (*gclocker_retry_count_ret) += 1;
594 }
595
596 // We can reach here if we were unsuccessful in scheduling a
597 // collection (because another thread beat us to it) or if we were
598 // stalled due to the GC locker. In either can we should retry the
599 // allocation attempt in case another thread successfully
600 // performed a collection and reclaimed enough space. We do the
601 // first attempt (without holding the Heap_lock) here and the
602 // follow-on attempt will be at the start of the next loop
603 // iteration (after taking the Heap_lock).
604 result = _allocator->attempt_allocation(word_size, context);
605 if (result != NULL) {
606 return result;
607 }
608
609 // Give a warning if we seem to be looping forever.
610 if ((QueuedAllocationWarningCount > 0) &&
611 (try_count % QueuedAllocationWarningCount == 0)) {
612 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
613 "retries %d times", try_count);
614 }
615 }
616
617 ShouldNotReachHere();
618 return NULL;
619 }
620
621 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
622 assert_at_safepoint(true /* should_be_vm_thread */);
623 if (_archive_allocator == NULL) {
624 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
625 }
626 }
627
628 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
629 // Allocations in archive regions cannot be of a size that would be considered
630 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
631 // may be different at archive-restore time.
632 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
633 }
634
635 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
636 assert_at_safepoint(true /* should_be_vm_thread */);
637 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
638 if (is_archive_alloc_too_large(word_size)) {
639 return NULL;
640 }
641 return _archive_allocator->archive_mem_allocate(word_size);
642 }
643
644 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
645 size_t end_alignment_in_bytes) {
646 assert_at_safepoint(true /* should_be_vm_thread */);
647 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
648
649 // Call complete_archive to do the real work, filling in the MemRegion
650 // array with the archive regions.
651 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
652 delete _archive_allocator;
653 _archive_allocator = NULL;
654 }
655
656 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
657 assert(ranges != NULL, "MemRegion array NULL");
658 assert(count != 0, "No MemRegions provided");
659 MemRegion reserved = _hrm.reserved();
660 for (size_t i = 0; i < count; i++) {
661 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
662 return false;
663 }
664 }
665 return true;
666 }
667
668 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
669 size_t count,
670 bool open) {
671 assert(!is_init_completed(), "Expect to be called at JVM init time");
672 assert(ranges != NULL, "MemRegion array NULL");
673 assert(count != 0, "No MemRegions provided");
674 MutexLockerEx x(Heap_lock);
675
676 MemRegion reserved = _hrm.reserved();
677 HeapWord* prev_last_addr = NULL;
678 HeapRegion* prev_last_region = NULL;
679
680 // Temporarily disable pretouching of heap pages. This interface is used
681 // when mmap'ing archived heap data in, so pre-touching is wasted.
682 FlagSetting fs(AlwaysPreTouch, false);
683
684 // Enable archive object checking used by G1MarkSweep. We have to let it know
685 // about each archive range, so that objects in those ranges aren't marked.
686 G1ArchiveAllocator::enable_archive_object_check();
687
688 // For each specified MemRegion range, allocate the corresponding G1
689 // regions and mark them as archive regions. We expect the ranges
690 // in ascending starting address order, without overlap.
691 for (size_t i = 0; i < count; i++) {
692 MemRegion curr_range = ranges[i];
693 HeapWord* start_address = curr_range.start();
694 size_t word_size = curr_range.word_size();
695 HeapWord* last_address = curr_range.last();
696 size_t commits = 0;
697
698 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
699 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
700 p2i(start_address), p2i(last_address));
701 guarantee(start_address > prev_last_addr,
702 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
703 p2i(start_address), p2i(prev_last_addr));
704 prev_last_addr = last_address;
705
706 // Check for ranges that start in the same G1 region in which the previous
707 // range ended, and adjust the start address so we don't try to allocate
708 // the same region again. If the current range is entirely within that
709 // region, skip it, just adjusting the recorded top.
710 HeapRegion* start_region = _hrm.addr_to_region(start_address);
711 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
712 start_address = start_region->end();
713 if (start_address > last_address) {
714 increase_used(word_size * HeapWordSize);
715 start_region->set_top(last_address + 1);
716 continue;
717 }
718 start_region->set_top(start_address);
719 curr_range = MemRegion(start_address, last_address + 1);
720 start_region = _hrm.addr_to_region(start_address);
721 }
722
723 // Perform the actual region allocation, exiting if it fails.
724 // Then note how much new space we have allocated.
725 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
726 return false;
727 }
728 increase_used(word_size * HeapWordSize);
729 if (commits != 0) {
730 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
731 HeapRegion::GrainWords * HeapWordSize * commits);
732
733 }
734
735 // Mark each G1 region touched by the range as archive, add it to
736 // the old set, and set the allocation context and top.
737 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
738 HeapRegion* last_region = _hrm.addr_to_region(last_address);
739 prev_last_region = last_region;
740
741 while (curr_region != NULL) {
742 assert(curr_region->is_empty() && !curr_region->is_pinned(),
743 "Region already in use (index %u)", curr_region->hrm_index());
744 curr_region->set_allocation_context(AllocationContext::system());
745 if (open) {
746 curr_region->set_open_archive();
747 } else {
748 curr_region->set_closed_archive();
749 }
750 _hr_printer.alloc(curr_region);
751 _old_set.add(curr_region);
752 HeapWord* top;
753 HeapRegion* next_region;
754 if (curr_region != last_region) {
755 top = curr_region->end();
756 next_region = _hrm.next_region_in_heap(curr_region);
757 } else {
758 top = last_address + 1;
759 next_region = NULL;
760 }
761 curr_region->set_top(top);
762 curr_region->set_first_dead(top);
763 curr_region->set_end_of_live(top);
764 curr_region = next_region;
765 }
766
767 // Notify mark-sweep of the archive
768 G1ArchiveAllocator::set_range_archive(curr_range, open);
769 }
770 return true;
771 }
772
773 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
774 assert(!is_init_completed(), "Expect to be called at JVM init time");
775 assert(ranges != NULL, "MemRegion array NULL");
776 assert(count != 0, "No MemRegions provided");
777 MemRegion reserved = _hrm.reserved();
778 HeapWord *prev_last_addr = NULL;
779 HeapRegion* prev_last_region = NULL;
780
781 // For each MemRegion, create filler objects, if needed, in the G1 regions
782 // that contain the address range. The address range actually within the
783 // MemRegion will not be modified. That is assumed to have been initialized
784 // elsewhere, probably via an mmap of archived heap data.
785 MutexLockerEx x(Heap_lock);
786 for (size_t i = 0; i < count; i++) {
787 HeapWord* start_address = ranges[i].start();
788 HeapWord* last_address = ranges[i].last();
789
790 assert(reserved.contains(start_address) && reserved.contains(last_address),
791 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
792 p2i(start_address), p2i(last_address));
793 assert(start_address > prev_last_addr,
794 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
795 p2i(start_address), p2i(prev_last_addr));
796
797 HeapRegion* start_region = _hrm.addr_to_region(start_address);
798 HeapRegion* last_region = _hrm.addr_to_region(last_address);
799 HeapWord* bottom_address = start_region->bottom();
800
801 // Check for a range beginning in the same region in which the
802 // previous one ended.
803 if (start_region == prev_last_region) {
804 bottom_address = prev_last_addr + 1;
805 }
806
807 // Verify that the regions were all marked as archive regions by
808 // alloc_archive_regions.
809 HeapRegion* curr_region = start_region;
810 while (curr_region != NULL) {
811 guarantee(curr_region->is_archive(),
812 "Expected archive region at index %u", curr_region->hrm_index());
813 if (curr_region != last_region) {
814 curr_region = _hrm.next_region_in_heap(curr_region);
815 } else {
816 curr_region = NULL;
817 }
818 }
819
820 prev_last_addr = last_address;
821 prev_last_region = last_region;
822
823 // Fill the memory below the allocated range with dummy object(s),
824 // if the region bottom does not match the range start, or if the previous
825 // range ended within the same G1 region, and there is a gap.
826 if (start_address != bottom_address) {
827 size_t fill_size = pointer_delta(start_address, bottom_address);
828 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
829 increase_used(fill_size * HeapWordSize);
830 }
831 }
832 }
833
834 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
835 uint* gc_count_before_ret,
836 uint* gclocker_retry_count_ret) {
837 assert_heap_not_locked_and_not_at_safepoint();
838 assert(!is_humongous(word_size), "attempt_allocation() should not "
839 "be called for humongous allocation requests");
840
841 AllocationContext_t context = AllocationContext::current();
842 HeapWord* result = _allocator->attempt_allocation(word_size, context);
843
844 if (result == NULL) {
845 result = attempt_allocation_slow(word_size,
846 context,
847 gc_count_before_ret,
848 gclocker_retry_count_ret);
849 }
850 assert_heap_not_locked();
851 if (result != NULL) {
852 dirty_young_block(result, word_size);
853 }
854 return result;
855 }
856
857 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
858 assert(!is_init_completed(), "Expect to be called at JVM init time");
859 assert(ranges != NULL, "MemRegion array NULL");
860 assert(count != 0, "No MemRegions provided");
861 MemRegion reserved = _hrm.reserved();
862 HeapWord* prev_last_addr = NULL;
863 HeapRegion* prev_last_region = NULL;
864 size_t size_used = 0;
865 size_t uncommitted_regions = 0;
866
867 // For each Memregion, free the G1 regions that constitute it, and
868 // notify mark-sweep that the range is no longer to be considered 'archive.'
869 MutexLockerEx x(Heap_lock);
870 for (size_t i = 0; i < count; i++) {
871 HeapWord* start_address = ranges[i].start();
872 HeapWord* last_address = ranges[i].last();
873
874 assert(reserved.contains(start_address) && reserved.contains(last_address),
875 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
876 p2i(start_address), p2i(last_address));
877 assert(start_address > prev_last_addr,
878 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
879 p2i(start_address), p2i(prev_last_addr));
880 size_used += ranges[i].byte_size();
881 prev_last_addr = last_address;
882
883 HeapRegion* start_region = _hrm.addr_to_region(start_address);
884 HeapRegion* last_region = _hrm.addr_to_region(last_address);
885
886 // Check for ranges that start in the same G1 region in which the previous
887 // range ended, and adjust the start address so we don't try to free
888 // the same region again. If the current range is entirely within that
889 // region, skip it.
890 if (start_region == prev_last_region) {
891 start_address = start_region->end();
892 if (start_address > last_address) {
893 continue;
894 }
895 start_region = _hrm.addr_to_region(start_address);
896 }
897 prev_last_region = last_region;
898
899 // After verifying that each region was marked as an archive region by
900 // alloc_archive_regions, set it free and empty and uncommit it.
901 HeapRegion* curr_region = start_region;
902 while (curr_region != NULL) {
903 guarantee(curr_region->is_archive(),
904 "Expected archive region at index %u", curr_region->hrm_index());
905 uint curr_index = curr_region->hrm_index();
906 _old_set.remove(curr_region);
907 curr_region->set_free();
908 curr_region->set_top(curr_region->bottom());
909 if (curr_region != last_region) {
910 curr_region = _hrm.next_region_in_heap(curr_region);
911 } else {
912 curr_region = NULL;
913 }
914 _hrm.shrink_at(curr_index, 1);
915 uncommitted_regions++;
916 }
917
918 // Notify mark-sweep that this is no longer an archive range.
919 G1ArchiveAllocator::set_range_archive(ranges[i], false);
920 }
921
922 if (uncommitted_regions != 0) {
923 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
924 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
925 }
926 decrease_used(size_used);
927 }
928
929 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
930 uint* gc_count_before_ret,
931 uint* gclocker_retry_count_ret) {
932 // The structure of this method has a lot of similarities to
933 // attempt_allocation_slow(). The reason these two were not merged
934 // into a single one is that such a method would require several "if
935 // allocation is not humongous do this, otherwise do that"
936 // conditional paths which would obscure its flow. In fact, an early
937 // version of this code did use a unified method which was harder to
938 // follow and, as a result, it had subtle bugs that were hard to
939 // track down. So keeping these two methods separate allows each to
940 // be more readable. It will be good to keep these two in sync as
941 // much as possible.
942
943 assert_heap_not_locked_and_not_at_safepoint();
944 assert(is_humongous(word_size), "attempt_allocation_humongous() "
945 "should only be called for humongous allocations");
946
947 // Humongous objects can exhaust the heap quickly, so we should check if we
948 // need to start a marking cycle at each humongous object allocation. We do
949 // the check before we do the actual allocation. The reason for doing it
950 // before the allocation is that we avoid having to keep track of the newly
951 // allocated memory while we do a GC.
952 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
953 word_size)) {
954 collect(GCCause::_g1_humongous_allocation);
955 }
956
957 // We will loop until a) we manage to successfully perform the
958 // allocation or b) we successfully schedule a collection which
959 // fails to perform the allocation. b) is the only case when we'll
960 // return NULL.
961 HeapWord* result = NULL;
962 for (int try_count = 1; /* we'll return */; try_count += 1) {
963 bool should_try_gc;
964 uint gc_count_before;
965
966 {
967 MutexLockerEx x(Heap_lock);
968
969 // Given that humongous objects are not allocated in young
970 // regions, we'll first try to do the allocation without doing a
971 // collection hoping that there's enough space in the heap.
972 result = humongous_obj_allocate(word_size, AllocationContext::current());
973 if (result != NULL) {
974 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
975 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
976 return result;
977 }
978
979 if (GCLocker::is_active_and_needs_gc()) {
980 should_try_gc = false;
981 } else {
982 // The GCLocker may not be active but the GCLocker initiated
983 // GC may not yet have been performed (GCLocker::needs_gc()
984 // returns true). In this case we do not try this GC and
985 // wait until the GCLocker initiated GC is performed, and
986 // then retry the allocation.
987 if (GCLocker::needs_gc()) {
988 should_try_gc = false;
989 } else {
990 // Read the GC count while still holding the Heap_lock.
991 gc_count_before = total_collections();
992 should_try_gc = true;
993 }
994 }
995 }
996
997 if (should_try_gc) {
998 // If we failed to allocate the humongous object, we should try to
999 // do a collection pause (if we're allowed) in case it reclaims
1000 // enough space for the allocation to succeed after the pause.
1001
1002 bool succeeded;
1003 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1004 GCCause::_g1_humongous_allocation);
1005 if (result != NULL) {
1006 assert(succeeded, "only way to get back a non-NULL result");
1007 return result;
1008 }
1009
1010 if (succeeded) {
1011 // If we get here we successfully scheduled a collection which
1012 // failed to allocate. No point in trying to allocate
1013 // further. We'll just return NULL.
1014 MutexLockerEx x(Heap_lock);
1015 *gc_count_before_ret = total_collections();
1016 return NULL;
1017 }
1018 } else {
1019 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1020 MutexLockerEx x(Heap_lock);
1021 *gc_count_before_ret = total_collections();
1022 return NULL;
1023 }
1024 // The GCLocker is either active or the GCLocker initiated
1025 // GC has not yet been performed. Stall until it is and
1026 // then retry the allocation.
1027 GCLocker::stall_until_clear();
1028 (*gclocker_retry_count_ret) += 1;
1029 }
1030
1031 // We can reach here if we were unsuccessful in scheduling a
1032 // collection (because another thread beat us to it) or if we were
1033 // stalled due to the GC locker. In either can we should retry the
1034 // allocation attempt in case another thread successfully
1035 // performed a collection and reclaimed enough space. Give a
1036 // warning if we seem to be looping forever.
1037
1038 if ((QueuedAllocationWarningCount > 0) &&
1039 (try_count % QueuedAllocationWarningCount == 0)) {
1040 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1041 "retries %d times", try_count);
1042 }
1043 }
1044
1045 ShouldNotReachHere();
1046 return NULL;
1047 }
1048
1049 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1050 AllocationContext_t context,
1051 bool expect_null_mutator_alloc_region) {
1052 assert_at_safepoint(true /* should_be_vm_thread */);
1053 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1054 "the current alloc region was unexpectedly found to be non-NULL");
1055
1056 if (!is_humongous(word_size)) {
1057 return _allocator->attempt_allocation_locked(word_size, context);
1058 } else {
1059 HeapWord* result = humongous_obj_allocate(word_size, context);
1060 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1061 collector_state()->set_initiate_conc_mark_if_possible(true);
1062 }
1063 return result;
1064 }
1065
1066 ShouldNotReachHere();
1067 }
1068
1069 class PostCompactionPrinterClosure: public HeapRegionClosure {
1070 private:
1071 G1HRPrinter* _hr_printer;
1072 public:
1073 bool doHeapRegion(HeapRegion* hr) {
1074 assert(!hr->is_young(), "not expecting to find young regions");
1075 _hr_printer->post_compaction(hr);
1076 return false;
1077 }
1078
1079 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1080 : _hr_printer(hr_printer) { }
1081 };
1082
1083 void G1CollectedHeap::print_hrm_post_compaction() {
1084 if (_hr_printer.is_active()) {
1085 PostCompactionPrinterClosure cl(hr_printer());
1086 heap_region_iterate(&cl);
1087 }
1088
1089 }
1090
1091 void G1CollectedHeap::abort_concurrent_cycle() {
1092 // Note: When we have a more flexible GC logging framework that
1093 // allows us to add optional attributes to a GC log record we
1094 // could consider timing and reporting how long we wait in the
1095 // following two methods.
1096 wait_while_free_regions_coming();
1097 // If we start the compaction before the CM threads finish
1098 // scanning the root regions we might trip them over as we'll
1099 // be moving objects / updating references. So let's wait until
1100 // they are done. By telling them to abort, they should complete
1101 // early.
1102 _cm->root_regions()->abort();
1103 _cm->root_regions()->wait_until_scan_finished();
1104 append_secondary_free_list_if_not_empty_with_lock();
1105
1106 // Disable discovery and empty the discovered lists
1107 // for the CM ref processor.
1108 ref_processor_cm()->disable_discovery();
1109 ref_processor_cm()->abandon_partial_discovery();
1110 ref_processor_cm()->verify_no_references_recorded();
1111
1112 // Abandon current iterations of concurrent marking and concurrent
1113 // refinement, if any are in progress.
1114 concurrent_mark()->abort();
1115 }
1116
1117 void G1CollectedHeap::prepare_heap_for_full_collection() {
1118 // Make sure we'll choose a new allocation region afterwards.
1119 _allocator->release_mutator_alloc_region();
1120 _allocator->abandon_gc_alloc_regions();
1121 g1_rem_set()->cleanupHRRS();
1122
1123 // We may have added regions to the current incremental collection
1124 // set between the last GC or pause and now. We need to clear the
1125 // incremental collection set and then start rebuilding it afresh
1126 // after this full GC.
1127 abandon_collection_set(collection_set());
1128
1129 tear_down_region_sets(false /* free_list_only */);
1130 collector_state()->set_gcs_are_young(true);
1131 }
1132
1133 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1134 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1135 assert(used() == recalculate_used(), "Should be equal");
1136 _verifier->verify_region_sets_optional();
1137 _verifier->verify_before_gc();
1138 _verifier->check_bitmaps("Full GC Start");
1139 }
1140
1141 void G1CollectedHeap::prepare_heap_for_mutators() {
1142 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1143 ClassLoaderDataGraph::purge();
1144 MetaspaceAux::verify_metrics();
1145
1146 // Prepare heap for normal collections.
1147 assert(num_free_regions() == 0, "we should not have added any free regions");
1148 rebuild_region_sets(false /* free_list_only */);
1149 abort_refinement();
1150 resize_if_necessary_after_full_collection();
1151
1152 // Rebuild the strong code root lists for each region
1153 rebuild_strong_code_roots();
1154
1155 // Start a new incremental collection set for the next pause
1156 start_new_collection_set();
1157
1158 _allocator->init_mutator_alloc_region();
1159
1160 // Post collection state updates.
1161 MetaspaceGC::compute_new_size();
1162 }
1163
1164 void G1CollectedHeap::abort_refinement() {
1165 if (_hot_card_cache->use_cache()) {
1166 _hot_card_cache->reset_hot_cache();
1167 }
1168
1169 // Discard all remembered set updates.
1170 JavaThread::dirty_card_queue_set().abandon_logs();
1171 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1172 }
1173
1174 void G1CollectedHeap::verify_after_full_collection() {
1175 check_gc_time_stamps();
1176 _hrm.verify_optional();
1177 _verifier->verify_region_sets_optional();
1178 _verifier->verify_after_gc();
1179 // Clear the previous marking bitmap, if needed for bitmap verification.
1180 // Note we cannot do this when we clear the next marking bitmap in
1181 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1182 // objects marked during a full GC against the previous bitmap.
1183 // But we need to clear it before calling check_bitmaps below since
1184 // the full GC has compacted objects and updated TAMS but not updated
1185 // the prev bitmap.
1186 if (G1VerifyBitmaps) {
1187 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1188 _cm->clear_prev_bitmap(workers());
1189 }
1190 _verifier->check_bitmaps("Full GC End");
1191
1192 // At this point there should be no regions in the
1193 // entire heap tagged as young.
1194 assert(check_young_list_empty(), "young list should be empty at this point");
1195
1196 // Note: since we've just done a full GC, concurrent
1197 // marking is no longer active. Therefore we need not
1198 // re-enable reference discovery for the CM ref processor.
1199 // That will be done at the start of the next marking cycle.
1200 // We also know that the STW processor should no longer
1201 // discover any new references.
1202 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1203 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1204 ref_processor_stw()->verify_no_references_recorded();
1205 ref_processor_cm()->verify_no_references_recorded();
1206 }
1207
1208 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1209 // Post collection logging.
1210 // We should do this after we potentially resize the heap so
1211 // that all the COMMIT / UNCOMMIT events are generated before
1212 // the compaction events.
1213 print_hrm_post_compaction();
1214 heap_transition->print();
1215 print_heap_after_gc();
1216 print_heap_regions();
1217 #ifdef TRACESPINNING
1218 ParallelTaskTerminator::print_termination_counts();
1219 #endif
1220 }
1221
1222 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1223 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1224 g1_policy()->record_full_collection_start();
1225
1226 print_heap_before_gc();
1227 print_heap_regions();
1228
1229 abort_concurrent_cycle();
1230 verify_before_full_collection(scope->is_explicit_gc());
1231
1232 gc_prologue(true);
1233 prepare_heap_for_full_collection();
1234
1235 G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->next_mark_bitmap(), workers()->active_workers());
1236 collector.prepare_collection();
1237 collector.collect();
1238 collector.complete_collection();
1239
1240 prepare_heap_for_mutators();
1241
1242 g1_policy()->record_full_collection_end();
1243 gc_epilogue(true);
1244
1245 verify_after_full_collection();
1246
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 // Capacity, free and used after the GC counted as full regions to
1279 // include the waste in the following calculations.
1280 const size_t capacity_after_gc = capacity();
1281 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
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 live: " SIZE_FORMAT "B "
1336 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1337 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1338
1339 expand(expand_bytes, _workers);
1340
1341 // No expansion, now see if we want to shrink
1342 } else if (capacity_after_gc > maximum_desired_capacity) {
1343 // Capacity too large, compute shrinking size
1344 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1345
1346 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1347 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1348 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1349 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1350
1351 shrink(shrink_bytes);
1352 }
1353 }
1354
1355 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1356 AllocationContext_t context,
1357 bool do_gc,
1358 bool clear_all_soft_refs,
1359 bool expect_null_mutator_alloc_region,
1360 bool* gc_succeeded) {
1361 *gc_succeeded = true;
1362 // Let's attempt the allocation first.
1363 HeapWord* result =
1364 attempt_allocation_at_safepoint(word_size,
1365 context,
1366 expect_null_mutator_alloc_region);
1367 if (result != NULL) {
1368 assert(*gc_succeeded, "sanity");
1369 return result;
1370 }
1371
1372 // In a G1 heap, we're supposed to keep allocation from failing by
1373 // incremental pauses. Therefore, at least for now, we'll favor
1374 // expansion over collection. (This might change in the future if we can
1375 // do something smarter than full collection to satisfy a failed alloc.)
1376 result = expand_and_allocate(word_size, context);
1377 if (result != NULL) {
1378 assert(*gc_succeeded, "sanity");
1379 return result;
1380 }
1381
1382 if (do_gc) {
1383 // Expansion didn't work, we'll try to do a Full GC.
1384 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1385 clear_all_soft_refs);
1386 }
1387
1388 return NULL;
1389 }
1390
1391 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1392 AllocationContext_t context,
1393 bool* succeeded) {
1394 assert_at_safepoint(true /* should_be_vm_thread */);
1395
1396 // Attempts to allocate followed by Full GC.
1397 HeapWord* result =
1398 satisfy_failed_allocation_helper(word_size,
1399 context,
1400 true, /* do_gc */
1401 false, /* clear_all_soft_refs */
1402 false, /* expect_null_mutator_alloc_region */
1403 succeeded);
1404
1405 if (result != NULL || !*succeeded) {
1406 return result;
1407 }
1408
1409 // Attempts to allocate followed by Full GC that will collect all soft references.
1410 result = satisfy_failed_allocation_helper(word_size,
1411 context,
1412 true, /* do_gc */
1413 true, /* clear_all_soft_refs */
1414 true, /* expect_null_mutator_alloc_region */
1415 succeeded);
1416
1417 if (result != NULL || !*succeeded) {
1418 return result;
1419 }
1420
1421 // Attempts to allocate, no GC
1422 result = satisfy_failed_allocation_helper(word_size,
1423 context,
1424 false, /* do_gc */
1425 false, /* clear_all_soft_refs */
1426 true, /* expect_null_mutator_alloc_region */
1427 succeeded);
1428
1429 if (result != NULL) {
1430 assert(*succeeded, "sanity");
1431 return result;
1432 }
1433
1434 assert(!collector_policy()->should_clear_all_soft_refs(),
1435 "Flag should have been handled and cleared prior to this point");
1436
1437 // What else? We might try synchronous finalization later. If the total
1438 // space available is large enough for the allocation, then a more
1439 // complete compaction phase than we've tried so far might be
1440 // appropriate.
1441 assert(*succeeded, "sanity");
1442 return NULL;
1443 }
1444
1445 // Attempting to expand the heap sufficiently
1446 // to support an allocation of the given "word_size". If
1447 // successful, perform the allocation and return the address of the
1448 // allocated block, or else "NULL".
1449
1450 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1451 assert_at_safepoint(true /* should_be_vm_thread */);
1452
1453 _verifier->verify_region_sets_optional();
1454
1455 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1456 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1457 word_size * HeapWordSize);
1458
1459
1460 if (expand(expand_bytes, _workers)) {
1461 _hrm.verify_optional();
1462 _verifier->verify_region_sets_optional();
1463 return attempt_allocation_at_safepoint(word_size,
1464 context,
1465 false /* expect_null_mutator_alloc_region */);
1466 }
1467 return NULL;
1468 }
1469
1470 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1471 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1472 aligned_expand_bytes = align_up(aligned_expand_bytes,
1473 HeapRegion::GrainBytes);
1474
1475 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1476 expand_bytes, aligned_expand_bytes);
1477
1478 if (is_maximal_no_gc()) {
1479 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1480 return false;
1481 }
1482
1483 double expand_heap_start_time_sec = os::elapsedTime();
1484 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1485 assert(regions_to_expand > 0, "Must expand by at least one region");
1486
1487 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1488 if (expand_time_ms != NULL) {
1489 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1490 }
1491
1492 if (expanded_by > 0) {
1493 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1494 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1495 g1_policy()->record_new_heap_size(num_regions());
1496 } else {
1497 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1498
1499 // The expansion of the virtual storage space was unsuccessful.
1500 // Let's see if it was because we ran out of swap.
1501 if (G1ExitOnExpansionFailure &&
1502 _hrm.available() >= regions_to_expand) {
1503 // We had head room...
1504 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1505 }
1506 }
1507 return regions_to_expand > 0;
1508 }
1509
1510 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1511 size_t aligned_shrink_bytes =
1512 ReservedSpace::page_align_size_down(shrink_bytes);
1513 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1514 HeapRegion::GrainBytes);
1515 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1516
1517 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1518 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1519
1520
1521 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1522 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1523 if (num_regions_removed > 0) {
1524 g1_policy()->record_new_heap_size(num_regions());
1525 } else {
1526 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1527 }
1528 }
1529
1530 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1531 _verifier->verify_region_sets_optional();
1532
1533 // We should only reach here at the end of a Full GC which means we
1534 // should not not be holding to any GC alloc regions. The method
1535 // below will make sure of that and do any remaining clean up.
1536 _allocator->abandon_gc_alloc_regions();
1537
1538 // Instead of tearing down / rebuilding the free lists here, we
1539 // could instead use the remove_all_pending() method on free_list to
1540 // remove only the ones that we need to remove.
1541 tear_down_region_sets(true /* free_list_only */);
1542 shrink_helper(shrink_bytes);
1543 rebuild_region_sets(true /* free_list_only */);
1544
1545 _hrm.verify_optional();
1546 _verifier->verify_region_sets_optional();
1547 }
1548
1549 // Public methods.
1550
1551 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1552 CollectedHeap(),
1553 _young_gen_sampling_thread(NULL),
1554 _collector_policy(collector_policy),
1555 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1556 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1557 _g1_policy(create_g1_policy(_gc_timer_stw)),
1558 _collection_set(this, _g1_policy),
1559 _dirty_card_queue_set(false),
1560 _is_alive_closure_cm(this),
1561 _is_alive_closure_stw(this),
1562 _ref_processor_cm(NULL),
1563 _ref_processor_stw(NULL),
1564 _bot(NULL),
1565 _hot_card_cache(NULL),
1566 _g1_rem_set(NULL),
1567 _cr(NULL),
1568 _g1mm(NULL),
1569 _preserved_marks_set(true /* in_c_heap */),
1570 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1571 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1572 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1573 _humongous_reclaim_candidates(),
1574 _has_humongous_reclaim_candidates(false),
1575 _archive_allocator(NULL),
1576 _free_regions_coming(false),
1577 _gc_time_stamp(0),
1578 _summary_bytes_used(0),
1579 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1580 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1581 _expand_heap_after_alloc_failure(true),
1582 _old_marking_cycles_started(0),
1583 _old_marking_cycles_completed(0),
1584 _in_cset_fast_test() {
1585
1586 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1587 /* are_GC_task_threads */true,
1588 /* are_ConcurrentGC_threads */false);
1589 _workers->initialize_workers();
1590 _verifier = new G1HeapVerifier(this);
1591
1592 _allocator = G1Allocator::create_allocator(this);
1593
1594 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1595
1596 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1597
1598 // Override the default _filler_array_max_size so that no humongous filler
1599 // objects are created.
1600 _filler_array_max_size = _humongous_object_threshold_in_words;
1601
1602 uint n_queues = ParallelGCThreads;
1603 _task_queues = new RefToScanQueueSet(n_queues);
1604
1605 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1606
1607 for (uint i = 0; i < n_queues; i++) {
1608 RefToScanQueue* q = new RefToScanQueue();
1609 q->initialize();
1610 _task_queues->register_queue(i, q);
1611 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1612 }
1613
1614 // Initialize the G1EvacuationFailureALot counters and flags.
1615 NOT_PRODUCT(reset_evacuation_should_fail();)
1616
1617 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1618 }
1619
1620 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1621 size_t size,
1622 size_t translation_factor) {
1623 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1624 // Allocate a new reserved space, preferring to use large pages.
1625 ReservedSpace rs(size, preferred_page_size);
1626 G1RegionToSpaceMapper* result =
1627 G1RegionToSpaceMapper::create_mapper(rs,
1628 size,
1629 rs.alignment(),
1630 HeapRegion::GrainBytes,
1631 translation_factor,
1632 mtGC);
1633
1634 os::trace_page_sizes_for_requested_size(description,
1635 size,
1636 preferred_page_size,
1637 rs.alignment(),
1638 rs.base(),
1639 rs.size());
1640
1641 return result;
1642 }
1643
1644 jint G1CollectedHeap::initialize_concurrent_refinement() {
1645 jint ecode = JNI_OK;
1646 _cr = G1ConcurrentRefine::create(&ecode);
1647 return ecode;
1648 }
1649
1650 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1651 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1652 if (_young_gen_sampling_thread->osthread() == NULL) {
1653 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1654 return JNI_ENOMEM;
1655 }
1656 return JNI_OK;
1657 }
1658
1659 jint G1CollectedHeap::initialize() {
1660 CollectedHeap::pre_initialize();
1661 os::enable_vtime();
1662
1663 // Necessary to satisfy locking discipline assertions.
1664
1665 MutexLocker x(Heap_lock);
1666
1667 // While there are no constraints in the GC code that HeapWordSize
1668 // be any particular value, there are multiple other areas in the
1669 // system which believe this to be true (e.g. oop->object_size in some
1670 // cases incorrectly returns the size in wordSize units rather than
1671 // HeapWordSize).
1672 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1673
1674 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1675 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1676 size_t heap_alignment = collector_policy()->heap_alignment();
1677
1678 // Ensure that the sizes are properly aligned.
1679 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1680 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1681 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1682
1683 // Reserve the maximum.
1684
1685 // When compressed oops are enabled, the preferred heap base
1686 // is calculated by subtracting the requested size from the
1687 // 32Gb boundary and using the result as the base address for
1688 // heap reservation. If the requested size is not aligned to
1689 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1690 // into the ReservedHeapSpace constructor) then the actual
1691 // base of the reserved heap may end up differing from the
1692 // address that was requested (i.e. the preferred heap base).
1693 // If this happens then we could end up using a non-optimal
1694 // compressed oops mode.
1695
1696 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1697 heap_alignment);
1698
1699 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1700
1701 // Create the barrier set for the entire reserved region.
1702 G1SATBCardTableLoggingModRefBS* bs
1703 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1704 bs->initialize();
1705 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1706 set_barrier_set(bs);
1707
1708 // Create the hot card cache.
1709 _hot_card_cache = new G1HotCardCache(this);
1710
1711 // Carve out the G1 part of the heap.
1712 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1713 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1714 G1RegionToSpaceMapper* heap_storage =
1715 G1RegionToSpaceMapper::create_mapper(g1_rs,
1716 g1_rs.size(),
1717 page_size,
1718 HeapRegion::GrainBytes,
1719 1,
1720 mtJavaHeap);
1721 os::trace_page_sizes("Heap",
1722 collector_policy()->min_heap_byte_size(),
1723 max_byte_size,
1724 page_size,
1725 heap_rs.base(),
1726 heap_rs.size());
1727 heap_storage->set_mapping_changed_listener(&_listener);
1728
1729 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1730 G1RegionToSpaceMapper* bot_storage =
1731 create_aux_memory_mapper("Block Offset Table",
1732 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1733 G1BlockOffsetTable::heap_map_factor());
1734
1735 G1RegionToSpaceMapper* cardtable_storage =
1736 create_aux_memory_mapper("Card Table",
1737 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1738 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1739
1740 G1RegionToSpaceMapper* card_counts_storage =
1741 create_aux_memory_mapper("Card Counts Table",
1742 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1743 G1CardCounts::heap_map_factor());
1744
1745 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1746 G1RegionToSpaceMapper* prev_bitmap_storage =
1747 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1748 G1RegionToSpaceMapper* next_bitmap_storage =
1749 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750
1751 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1752 g1_barrier_set()->initialize(cardtable_storage);
1753 // Do later initialization work for concurrent refinement.
1754 _hot_card_cache->initialize(card_counts_storage);
1755
1756 // 6843694 - ensure that the maximum region index can fit
1757 // in the remembered set structures.
1758 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1759 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1760
1761 // Also create a G1 rem set.
1762 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1763 _g1_rem_set->initialize(max_capacity(), max_regions());
1764
1765 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1766 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1767 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1768 "too many cards per region");
1769
1770 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1771
1772 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1773
1774 {
1775 HeapWord* start = _hrm.reserved().start();
1776 HeapWord* end = _hrm.reserved().end();
1777 size_t granularity = HeapRegion::GrainBytes;
1778
1779 _in_cset_fast_test.initialize(start, end, granularity);
1780 _humongous_reclaim_candidates.initialize(start, end, granularity);
1781 }
1782
1783 // Create the G1ConcurrentMark data structure and thread.
1784 // (Must do this late, so that "max_regions" is defined.)
1785 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1786 if (_cm == NULL || !_cm->completed_initialization()) {
1787 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1788 return JNI_ENOMEM;
1789 }
1790 _cmThread = _cm->cm_thread();
1791
1792 // Now expand into the initial heap size.
1793 if (!expand(init_byte_size, _workers)) {
1794 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1795 return JNI_ENOMEM;
1796 }
1797
1798 // Perform any initialization actions delegated to the policy.
1799 g1_policy()->init(this, &_collection_set);
1800
1801 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1802 SATB_Q_FL_lock,
1803 G1SATBProcessCompletedThreshold,
1804 Shared_SATB_Q_lock);
1805
1806 jint ecode = initialize_concurrent_refinement();
1807 if (ecode != JNI_OK) {
1808 return ecode;
1809 }
1810
1811 ecode = initialize_young_gen_sampling_thread();
1812 if (ecode != JNI_OK) {
1813 return ecode;
1814 }
1815
1816 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1817 DirtyCardQ_FL_lock,
1818 (int)concurrent_refine()->yellow_zone(),
1819 (int)concurrent_refine()->red_zone(),
1820 Shared_DirtyCardQ_lock,
1821 NULL, // fl_owner
1822 true); // init_free_ids
1823
1824 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1825 DirtyCardQ_FL_lock,
1826 -1, // never trigger processing
1827 -1, // no limit on length
1828 Shared_DirtyCardQ_lock,
1829 &JavaThread::dirty_card_queue_set());
1830
1831 // Here we allocate the dummy HeapRegion that is required by the
1832 // G1AllocRegion class.
1833 HeapRegion* dummy_region = _hrm.get_dummy_region();
1834
1835 // We'll re-use the same region whether the alloc region will
1836 // require BOT updates or not and, if it doesn't, then a non-young
1837 // region will complain that it cannot support allocations without
1838 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1839 dummy_region->set_eden();
1840 // Make sure it's full.
1841 dummy_region->set_top(dummy_region->end());
1842 G1AllocRegion::setup(this, dummy_region);
1843
1844 _allocator->init_mutator_alloc_region();
1845
1846 // Do create of the monitoring and management support so that
1847 // values in the heap have been properly initialized.
1848 _g1mm = new G1MonitoringSupport(this);
1849
1850 G1StringDedup::initialize();
1851
1852 _preserved_marks_set.init(ParallelGCThreads);
1853
1854 _collection_set.initialize(max_regions());
1855
1856 return JNI_OK;
1857 }
1858
1859 void G1CollectedHeap::stop() {
1860 // Stop all concurrent threads. We do this to make sure these threads
1861 // do not continue to execute and access resources (e.g. logging)
1862 // that are destroyed during shutdown.
1863 _cr->stop();
1864 _young_gen_sampling_thread->stop();
1865 _cmThread->stop();
1866 if (G1StringDedup::is_enabled()) {
1867 G1StringDedup::stop();
1868 }
1869 }
1870
1871 void G1CollectedHeap::safepoint_synchronize_begin() {
1872 SuspendibleThreadSet::synchronize();
1873 }
1874
1875 void G1CollectedHeap::safepoint_synchronize_end() {
1876 SuspendibleThreadSet::desynchronize();
1877 }
1878
1879 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1880 return HeapRegion::max_region_size();
1881 }
1882
1883 void G1CollectedHeap::post_initialize() {
1884 ref_processing_init();
1885 }
1886
1887 void G1CollectedHeap::ref_processing_init() {
1888 // Reference processing in G1 currently works as follows:
1889 //
1890 // * There are two reference processor instances. One is
1891 // used to record and process discovered references
1892 // during concurrent marking; the other is used to
1893 // record and process references during STW pauses
1894 // (both full and incremental).
1895 // * Both ref processors need to 'span' the entire heap as
1896 // the regions in the collection set may be dotted around.
1897 //
1898 // * For the concurrent marking ref processor:
1899 // * Reference discovery is enabled at initial marking.
1900 // * Reference discovery is disabled and the discovered
1901 // references processed etc during remarking.
1902 // * Reference discovery is MT (see below).
1903 // * Reference discovery requires a barrier (see below).
1904 // * Reference processing may or may not be MT
1905 // (depending on the value of ParallelRefProcEnabled
1906 // and ParallelGCThreads).
1907 // * A full GC disables reference discovery by the CM
1908 // ref processor and abandons any entries on it's
1909 // discovered lists.
1910 //
1911 // * For the STW processor:
1912 // * Non MT discovery is enabled at the start of a full GC.
1913 // * Processing and enqueueing during a full GC is non-MT.
1914 // * During a full GC, references are processed after marking.
1915 //
1916 // * Discovery (may or may not be MT) is enabled at the start
1917 // of an incremental evacuation pause.
1918 // * References are processed near the end of a STW evacuation pause.
1919 // * For both types of GC:
1920 // * Discovery is atomic - i.e. not concurrent.
1921 // * Reference discovery will not need a barrier.
1922
1923 MemRegion mr = reserved_region();
1924
1925 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1926
1927 // Concurrent Mark ref processor
1928 _ref_processor_cm =
1929 new ReferenceProcessor(mr, // span
1930 mt_processing,
1931 // mt processing
1932 ParallelGCThreads,
1933 // degree of mt processing
1934 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1935 // mt discovery
1936 MAX2(ParallelGCThreads, ConcGCThreads),
1937 // degree of mt discovery
1938 false,
1939 // Reference discovery is not atomic
1940 &_is_alive_closure_cm);
1941 // is alive closure
1942 // (for efficiency/performance)
1943
1944 // STW ref processor
1945 _ref_processor_stw =
1946 new ReferenceProcessor(mr, // span
1947 mt_processing,
1948 // mt processing
1949 ParallelGCThreads,
1950 // degree of mt processing
1951 (ParallelGCThreads > 1),
1952 // mt discovery
1953 ParallelGCThreads,
1954 // degree of mt discovery
1955 true,
1956 // Reference discovery is atomic
1957 &_is_alive_closure_stw);
1958 // is alive closure
1959 // (for efficiency/performance)
1960 }
1961
1962 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1963 return _collector_policy;
1964 }
1965
1966 size_t G1CollectedHeap::capacity() const {
1967 return _hrm.length() * HeapRegion::GrainBytes;
1968 }
1969
1970 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1971 return _hrm.total_free_bytes();
1972 }
1973
1974 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1975 hr->reset_gc_time_stamp();
1976 }
1977
1978 #ifndef PRODUCT
1979
1980 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1981 private:
1982 unsigned _gc_time_stamp;
1983 bool _failures;
1984
1985 public:
1986 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1987 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1988
1989 virtual bool doHeapRegion(HeapRegion* hr) {
1990 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1991 if (_gc_time_stamp != region_gc_time_stamp) {
1992 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1993 region_gc_time_stamp, _gc_time_stamp);
1994 _failures = true;
1995 }
1996 return false;
1997 }
1998
1999 bool failures() { return _failures; }
2000 };
2001
2002 void G1CollectedHeap::check_gc_time_stamps() {
2003 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2004 heap_region_iterate(&cl);
2005 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2006 }
2007 #endif // PRODUCT
2008
2009 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2010 _hot_card_cache->drain(cl, worker_i);
2011 }
2012
2013 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2014 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2015 size_t n_completed_buffers = 0;
2016 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
2017 n_completed_buffers++;
2018 }
2019 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2020 dcqs.clear_n_completed_buffers();
2021 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2022 }
2023
2024 // Computes the sum of the storage used by the various regions.
2025 size_t G1CollectedHeap::used() const {
2026 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2027 if (_archive_allocator != NULL) {
2028 result += _archive_allocator->used();
2029 }
2030 return result;
2031 }
2032
2033 size_t G1CollectedHeap::used_unlocked() const {
2034 return _summary_bytes_used;
2035 }
2036
2037 class SumUsedClosure: public HeapRegionClosure {
2038 size_t _used;
2039 public:
2040 SumUsedClosure() : _used(0) {}
2041 bool doHeapRegion(HeapRegion* r) {
2042 _used += r->used();
2043 return false;
2044 }
2045 size_t result() { return _used; }
2046 };
2047
2048 size_t G1CollectedHeap::recalculate_used() const {
2049 double recalculate_used_start = os::elapsedTime();
2050
2051 SumUsedClosure blk;
2052 heap_region_iterate(&blk);
2053
2054 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2055 return blk.result();
2056 }
2057
2058 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2059 switch (cause) {
2060 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2061 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2062 case GCCause::_update_allocation_context_stats_inc: return true;
2063 case GCCause::_wb_conc_mark: return true;
2064 default : return false;
2065 }
2066 }
2067
2068 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2069 switch (cause) {
2070 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2071 case GCCause::_g1_humongous_allocation: return true;
2072 default: return is_user_requested_concurrent_full_gc(cause);
2073 }
2074 }
2075
2076 #ifndef PRODUCT
2077 void G1CollectedHeap::allocate_dummy_regions() {
2078 // Let's fill up most of the region
2079 size_t word_size = HeapRegion::GrainWords - 1024;
2080 // And as a result the region we'll allocate will be humongous.
2081 guarantee(is_humongous(word_size), "sanity");
2082
2083 // _filler_array_max_size is set to humongous object threshold
2084 // but temporarily change it to use CollectedHeap::fill_with_object().
2085 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2086
2087 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2088 // Let's use the existing mechanism for the allocation
2089 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2090 AllocationContext::system());
2091 if (dummy_obj != NULL) {
2092 MemRegion mr(dummy_obj, word_size);
2093 CollectedHeap::fill_with_object(mr);
2094 } else {
2095 // If we can't allocate once, we probably cannot allocate
2096 // again. Let's get out of the loop.
2097 break;
2098 }
2099 }
2100 }
2101 #endif // !PRODUCT
2102
2103 void G1CollectedHeap::increment_old_marking_cycles_started() {
2104 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2105 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2106 "Wrong marking cycle count (started: %d, completed: %d)",
2107 _old_marking_cycles_started, _old_marking_cycles_completed);
2108
2109 _old_marking_cycles_started++;
2110 }
2111
2112 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2113 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2114
2115 // We assume that if concurrent == true, then the caller is a
2116 // concurrent thread that was joined the Suspendible Thread
2117 // Set. If there's ever a cheap way to check this, we should add an
2118 // assert here.
2119
2120 // Given that this method is called at the end of a Full GC or of a
2121 // concurrent cycle, and those can be nested (i.e., a Full GC can
2122 // interrupt a concurrent cycle), the number of full collections
2123 // completed should be either one (in the case where there was no
2124 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2125 // behind the number of full collections started.
2126
2127 // This is the case for the inner caller, i.e. a Full GC.
2128 assert(concurrent ||
2129 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2130 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2131 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2132 "is inconsistent with _old_marking_cycles_completed = %u",
2133 _old_marking_cycles_started, _old_marking_cycles_completed);
2134
2135 // This is the case for the outer caller, i.e. the concurrent cycle.
2136 assert(!concurrent ||
2137 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2138 "for outer caller (concurrent cycle): "
2139 "_old_marking_cycles_started = %u "
2140 "is inconsistent with _old_marking_cycles_completed = %u",
2141 _old_marking_cycles_started, _old_marking_cycles_completed);
2142
2143 _old_marking_cycles_completed += 1;
2144
2145 // We need to clear the "in_progress" flag in the CM thread before
2146 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2147 // is set) so that if a waiter requests another System.gc() it doesn't
2148 // incorrectly see that a marking cycle is still in progress.
2149 if (concurrent) {
2150 _cmThread->set_idle();
2151 }
2152
2153 // This notify_all() will ensure that a thread that called
2154 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2155 // and it's waiting for a full GC to finish will be woken up. It is
2156 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2157 FullGCCount_lock->notify_all();
2158 }
2159
2160 void G1CollectedHeap::collect(GCCause::Cause cause) {
2161 assert_heap_not_locked();
2162
2163 uint gc_count_before;
2164 uint old_marking_count_before;
2165 uint full_gc_count_before;
2166 bool retry_gc;
2167
2168 do {
2169 retry_gc = false;
2170
2171 {
2172 MutexLocker ml(Heap_lock);
2173
2174 // Read the GC count while holding the Heap_lock
2175 gc_count_before = total_collections();
2176 full_gc_count_before = total_full_collections();
2177 old_marking_count_before = _old_marking_cycles_started;
2178 }
2179
2180 if (should_do_concurrent_full_gc(cause)) {
2181 // Schedule an initial-mark evacuation pause that will start a
2182 // concurrent cycle. We're setting word_size to 0 which means that
2183 // we are not requesting a post-GC allocation.
2184 VM_G1IncCollectionPause op(gc_count_before,
2185 0, /* word_size */
2186 true, /* should_initiate_conc_mark */
2187 g1_policy()->max_pause_time_ms(),
2188 cause);
2189 op.set_allocation_context(AllocationContext::current());
2190
2191 VMThread::execute(&op);
2192 if (!op.pause_succeeded()) {
2193 if (old_marking_count_before == _old_marking_cycles_started) {
2194 retry_gc = op.should_retry_gc();
2195 } else {
2196 // A Full GC happened while we were trying to schedule the
2197 // initial-mark GC. No point in starting a new cycle given
2198 // that the whole heap was collected anyway.
2199 }
2200
2201 if (retry_gc) {
2202 if (GCLocker::is_active_and_needs_gc()) {
2203 GCLocker::stall_until_clear();
2204 }
2205 }
2206 }
2207 } else {
2208 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2209 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2210
2211 // Schedule a standard evacuation pause. We're setting word_size
2212 // to 0 which means that we are not requesting a post-GC allocation.
2213 VM_G1IncCollectionPause op(gc_count_before,
2214 0, /* word_size */
2215 false, /* should_initiate_conc_mark */
2216 g1_policy()->max_pause_time_ms(),
2217 cause);
2218 VMThread::execute(&op);
2219 } else {
2220 // Schedule a Full GC.
2221 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2222 VMThread::execute(&op);
2223 }
2224 }
2225 } while (retry_gc);
2226 }
2227
2228 bool G1CollectedHeap::is_in(const void* p) const {
2229 if (_hrm.reserved().contains(p)) {
2230 // Given that we know that p is in the reserved space,
2231 // heap_region_containing() should successfully
2232 // return the containing region.
2233 HeapRegion* hr = heap_region_containing(p);
2234 return hr->is_in(p);
2235 } else {
2236 return false;
2237 }
2238 }
2239
2240 #ifdef ASSERT
2241 bool G1CollectedHeap::is_in_exact(const void* p) const {
2242 bool contains = reserved_region().contains(p);
2243 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2244 if (contains && available) {
2245 return true;
2246 } else {
2247 return false;
2248 }
2249 }
2250 #endif
2251
2252 // Iteration functions.
2253
2254 // Iterates an ObjectClosure over all objects within a HeapRegion.
2255
2256 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2257 ObjectClosure* _cl;
2258 public:
2259 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2260 bool doHeapRegion(HeapRegion* r) {
2261 if (!r->is_continues_humongous()) {
2262 r->object_iterate(_cl);
2263 }
2264 return false;
2265 }
2266 };
2267
2268 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2269 IterateObjectClosureRegionClosure blk(cl);
2270 heap_region_iterate(&blk);
2271 }
2272
2273 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2274 _hrm.iterate(cl);
2275 }
2276
2277 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2278 HeapRegionClaimer *hrclaimer,
2279 uint worker_id) const {
2280 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2281 }
2282
2283 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2284 HeapRegionClaimer *hrclaimer) const {
2285 _hrm.par_iterate(cl, hrclaimer, 0);
2286 }
2287
2288 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2289 _collection_set.iterate(cl);
2290 }
2291
2292 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2293 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2294 }
2295
2296 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2297 HeapRegion* hr = heap_region_containing(addr);
2298 return hr->block_start(addr);
2299 }
2300
2301 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2302 HeapRegion* hr = heap_region_containing(addr);
2303 return hr->block_size(addr);
2304 }
2305
2306 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2307 HeapRegion* hr = heap_region_containing(addr);
2308 return hr->block_is_obj(addr);
2309 }
2310
2311 bool G1CollectedHeap::supports_tlab_allocation() const {
2312 return true;
2313 }
2314
2315 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2316 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2317 }
2318
2319 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2320 return _eden.length() * HeapRegion::GrainBytes;
2321 }
2322
2323 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2324 // must be equal to the humongous object limit.
2325 size_t G1CollectedHeap::max_tlab_size() const {
2326 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2327 }
2328
2329 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2330 AllocationContext_t context = AllocationContext::current();
2331 return _allocator->unsafe_max_tlab_alloc(context);
2332 }
2333
2334 size_t G1CollectedHeap::max_capacity() const {
2335 return _hrm.reserved().byte_size();
2336 }
2337
2338 jlong G1CollectedHeap::millis_since_last_gc() {
2339 // See the notes in GenCollectedHeap::millis_since_last_gc()
2340 // for more information about the implementation.
2341 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2342 _g1_policy->collection_pause_end_millis();
2343 if (ret_val < 0) {
2344 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2345 ". returning zero instead.", ret_val);
2346 return 0;
2347 }
2348 return ret_val;
2349 }
2350
2351 void G1CollectedHeap::prepare_for_verify() {
2352 _verifier->prepare_for_verify();
2353 }
2354
2355 void G1CollectedHeap::verify(VerifyOption vo) {
2356 _verifier->verify(vo);
2357 }
2358
2359 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2360 return true;
2361 }
2362
2363 const char* const* G1CollectedHeap::concurrent_phases() const {
2364 return _cmThread->concurrent_phases();
2365 }
2366
2367 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2368 return _cmThread->request_concurrent_phase(phase);
2369 }
2370
2371 class PrintRegionClosure: public HeapRegionClosure {
2372 outputStream* _st;
2373 public:
2374 PrintRegionClosure(outputStream* st) : _st(st) {}
2375 bool doHeapRegion(HeapRegion* r) {
2376 r->print_on(_st);
2377 return false;
2378 }
2379 };
2380
2381 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2382 const HeapRegion* hr,
2383 const VerifyOption vo) const {
2384 switch (vo) {
2385 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2386 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2387 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2388 default: ShouldNotReachHere();
2389 }
2390 return false; // keep some compilers happy
2391 }
2392
2393 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2394 const VerifyOption vo) const {
2395 switch (vo) {
2396 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2397 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2398 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2399 default: ShouldNotReachHere();
2400 }
2401 return false; // keep some compilers happy
2402 }
2403
2404 void G1CollectedHeap::print_heap_regions() const {
2405 LogTarget(Trace, gc, heap, region) lt;
2406 if (lt.is_enabled()) {
2407 LogStream ls(lt);
2408 print_regions_on(&ls);
2409 }
2410 }
2411
2412 void G1CollectedHeap::print_on(outputStream* st) const {
2413 st->print(" %-20s", "garbage-first heap");
2414 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2415 capacity()/K, used_unlocked()/K);
2416 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2417 p2i(_hrm.reserved().start()),
2418 p2i(_hrm.reserved().end()));
2419 st->cr();
2420 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2421 uint young_regions = young_regions_count();
2422 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2423 (size_t) young_regions * HeapRegion::GrainBytes / K);
2424 uint survivor_regions = survivor_regions_count();
2425 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2426 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2427 st->cr();
2428 MetaspaceAux::print_on(st);
2429 }
2430
2431 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2432 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2433 "HS=humongous(starts), HC=humongous(continues), "
2434 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2435 "AC=allocation context, "
2436 "TAMS=top-at-mark-start (previous, next)");
2437 PrintRegionClosure blk(st);
2438 heap_region_iterate(&blk);
2439 }
2440
2441 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2442 print_on(st);
2443
2444 // Print the per-region information.
2445 print_regions_on(st);
2446 }
2447
2448 void G1CollectedHeap::print_on_error(outputStream* st) const {
2449 this->CollectedHeap::print_on_error(st);
2450
2451 if (_cm != NULL) {
2452 st->cr();
2453 _cm->print_on_error(st);
2454 }
2455 }
2456
2457 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2458 workers()->print_worker_threads_on(st);
2459 _cmThread->print_on(st);
2460 st->cr();
2461 _cm->print_worker_threads_on(st);
2462 _cr->print_threads_on(st);
2463 _young_gen_sampling_thread->print_on(st);
2464 if (G1StringDedup::is_enabled()) {
2465 G1StringDedup::print_worker_threads_on(st);
2466 }
2467 }
2468
2469 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2470 workers()->threads_do(tc);
2471 tc->do_thread(_cmThread);
2472 _cm->threads_do(tc);
2473 _cr->threads_do(tc);
2474 tc->do_thread(_young_gen_sampling_thread);
2475 if (G1StringDedup::is_enabled()) {
2476 G1StringDedup::threads_do(tc);
2477 }
2478 }
2479
2480 void G1CollectedHeap::print_tracing_info() const {
2481 g1_rem_set()->print_summary_info();
2482 concurrent_mark()->print_summary_info();
2483 }
2484
2485 #ifndef PRODUCT
2486 // Helpful for debugging RSet issues.
2487
2488 class PrintRSetsClosure : public HeapRegionClosure {
2489 private:
2490 const char* _msg;
2491 size_t _occupied_sum;
2492
2493 public:
2494 bool doHeapRegion(HeapRegion* r) {
2495 HeapRegionRemSet* hrrs = r->rem_set();
2496 size_t occupied = hrrs->occupied();
2497 _occupied_sum += occupied;
2498
2499 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2500 if (occupied == 0) {
2501 tty->print_cr(" RSet is empty");
2502 } else {
2503 hrrs->print();
2504 }
2505 tty->print_cr("----------");
2506 return false;
2507 }
2508
2509 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2510 tty->cr();
2511 tty->print_cr("========================================");
2512 tty->print_cr("%s", msg);
2513 tty->cr();
2514 }
2515
2516 ~PrintRSetsClosure() {
2517 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2518 tty->print_cr("========================================");
2519 tty->cr();
2520 }
2521 };
2522
2523 void G1CollectedHeap::print_cset_rsets() {
2524 PrintRSetsClosure cl("Printing CSet RSets");
2525 collection_set_iterate(&cl);
2526 }
2527
2528 void G1CollectedHeap::print_all_rsets() {
2529 PrintRSetsClosure cl("Printing All RSets");;
2530 heap_region_iterate(&cl);
2531 }
2532 #endif // PRODUCT
2533
2534 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2535
2536 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2537 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2538 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2539
2540 size_t eden_capacity_bytes =
2541 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2542
2543 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2544 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2545 eden_capacity_bytes, survivor_used_bytes, num_regions());
2546 }
2547
2548 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2549 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2550 stats->unused(), stats->used(), stats->region_end_waste(),
2551 stats->regions_filled(), stats->direct_allocated(),
2552 stats->failure_used(), stats->failure_waste());
2553 }
2554
2555 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2556 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2557 gc_tracer->report_gc_heap_summary(when, heap_summary);
2558
2559 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2560 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2561 }
2562
2563 G1CollectedHeap* G1CollectedHeap::heap() {
2564 CollectedHeap* heap = Universe::heap();
2565 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2566 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2567 return (G1CollectedHeap*)heap;
2568 }
2569
2570 void G1CollectedHeap::gc_prologue(bool full) {
2571 // always_do_update_barrier = false;
2572 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2573
2574 // This summary needs to be printed before incrementing total collections.
2575 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2576
2577 // Update common counters.
2578 increment_total_collections(full /* full gc */);
2579 if (full) {
2580 increment_old_marking_cycles_started();
2581 reset_gc_time_stamp();
2582 } else {
2583 increment_gc_time_stamp();
2584 }
2585
2586 // Fill TLAB's and such
2587 double start = os::elapsedTime();
2588 accumulate_statistics_all_tlabs();
2589 ensure_parsability(true);
2590 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2591 }
2592
2593 void G1CollectedHeap::gc_epilogue(bool full) {
2594 // Update common counters.
2595 if (full) {
2596 // Update the number of full collections that have been completed.
2597 increment_old_marking_cycles_completed(false /* concurrent */);
2598 }
2599
2600 // We are at the end of the GC. Total collections has already been increased.
2601 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2602
2603 // FIXME: what is this about?
2604 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2605 // is set.
2606 #if COMPILER2_OR_JVMCI
2607 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2608 #endif
2609 // always_do_update_barrier = true;
2610
2611 double start = os::elapsedTime();
2612 resize_all_tlabs();
2613 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2614
2615 allocation_context_stats().update(full);
2616
2617 MemoryService::track_memory_usage();
2618 // We have just completed a GC. Update the soft reference
2619 // policy with the new heap occupancy
2620 Universe::update_heap_info_at_gc();
2621 }
2622
2623 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2624 uint gc_count_before,
2625 bool* succeeded,
2626 GCCause::Cause gc_cause) {
2627 assert_heap_not_locked_and_not_at_safepoint();
2628 VM_G1IncCollectionPause op(gc_count_before,
2629 word_size,
2630 false, /* should_initiate_conc_mark */
2631 g1_policy()->max_pause_time_ms(),
2632 gc_cause);
2633
2634 op.set_allocation_context(AllocationContext::current());
2635 VMThread::execute(&op);
2636
2637 HeapWord* result = op.result();
2638 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2639 assert(result == NULL || ret_succeeded,
2640 "the result should be NULL if the VM did not succeed");
2641 *succeeded = ret_succeeded;
2642
2643 assert_heap_not_locked();
2644 return result;
2645 }
2646
2647 void
2648 G1CollectedHeap::doConcurrentMark() {
2649 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2650 if (!_cmThread->in_progress()) {
2651 _cmThread->set_started();
2652 CGC_lock->notify();
2653 }
2654 }
2655
2656 size_t G1CollectedHeap::pending_card_num() {
2657 size_t extra_cards = 0;
2658 JavaThread *curr = Threads::first();
2659 while (curr != NULL) {
2660 DirtyCardQueue& dcq = curr->dirty_card_queue();
2661 extra_cards += dcq.size();
2662 curr = curr->next();
2663 }
2664 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2665 size_t buffer_size = dcqs.buffer_size();
2666 size_t buffer_num = dcqs.completed_buffers_num();
2667
2668 return buffer_size * buffer_num + extra_cards;
2669 }
2670
2671 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2672 private:
2673 size_t _total_humongous;
2674 size_t _candidate_humongous;
2675
2676 DirtyCardQueue _dcq;
2677
2678 // We don't nominate objects with many remembered set entries, on
2679 // the assumption that such objects are likely still live.
2680 bool is_remset_small(HeapRegion* region) const {
2681 HeapRegionRemSet* const rset = region->rem_set();
2682 return G1EagerReclaimHumongousObjectsWithStaleRefs
2683 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2684 : rset->is_empty();
2685 }
2686
2687 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2688 assert(region->is_starts_humongous(), "Must start a humongous object");
2689
2690 oop obj = oop(region->bottom());
2691
2692 // Dead objects cannot be eager reclaim candidates. Due to class
2693 // unloading it is unsafe to query their classes so we return early.
2694 if (heap->is_obj_dead(obj, region)) {
2695 return false;
2696 }
2697
2698 // Candidate selection must satisfy the following constraints
2699 // while concurrent marking is in progress:
2700 //
2701 // * In order to maintain SATB invariants, an object must not be
2702 // reclaimed if it was allocated before the start of marking and
2703 // has not had its references scanned. Such an object must have
2704 // its references (including type metadata) scanned to ensure no
2705 // live objects are missed by the marking process. Objects
2706 // allocated after the start of concurrent marking don't need to
2707 // be scanned.
2708 //
2709 // * An object must not be reclaimed if it is on the concurrent
2710 // mark stack. Objects allocated after the start of concurrent
2711 // marking are never pushed on the mark stack.
2712 //
2713 // Nominating only objects allocated after the start of concurrent
2714 // marking is sufficient to meet both constraints. This may miss
2715 // some objects that satisfy the constraints, but the marking data
2716 // structures don't support efficiently performing the needed
2717 // additional tests or scrubbing of the mark stack.
2718 //
2719 // However, we presently only nominate is_typeArray() objects.
2720 // A humongous object containing references induces remembered
2721 // set entries on other regions. In order to reclaim such an
2722 // object, those remembered sets would need to be cleaned up.
2723 //
2724 // We also treat is_typeArray() objects specially, allowing them
2725 // to be reclaimed even if allocated before the start of
2726 // concurrent mark. For this we rely on mark stack insertion to
2727 // exclude is_typeArray() objects, preventing reclaiming an object
2728 // that is in the mark stack. We also rely on the metadata for
2729 // such objects to be built-in and so ensured to be kept live.
2730 // Frequent allocation and drop of large binary blobs is an
2731 // important use case for eager reclaim, and this special handling
2732 // may reduce needed headroom.
2733
2734 return obj->is_typeArray() && is_remset_small(region);
2735 }
2736
2737 public:
2738 RegisterHumongousWithInCSetFastTestClosure()
2739 : _total_humongous(0),
2740 _candidate_humongous(0),
2741 _dcq(&JavaThread::dirty_card_queue_set()) {
2742 }
2743
2744 virtual bool doHeapRegion(HeapRegion* r) {
2745 if (!r->is_starts_humongous()) {
2746 return false;
2747 }
2748 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2749
2750 bool is_candidate = humongous_region_is_candidate(g1h, r);
2751 uint rindex = r->hrm_index();
2752 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2753 if (is_candidate) {
2754 _candidate_humongous++;
2755 g1h->register_humongous_region_with_cset(rindex);
2756 // Is_candidate already filters out humongous object with large remembered sets.
2757 // If we have a humongous object with a few remembered sets, we simply flush these
2758 // remembered set entries into the DCQS. That will result in automatic
2759 // re-evaluation of their remembered set entries during the following evacuation
2760 // phase.
2761 if (!r->rem_set()->is_empty()) {
2762 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2763 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2764 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2765 HeapRegionRemSetIterator hrrs(r->rem_set());
2766 size_t card_index;
2767 while (hrrs.has_next(card_index)) {
2768 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2769 // The remembered set might contain references to already freed
2770 // regions. Filter out such entries to avoid failing card table
2771 // verification.
2772 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2773 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2774 *card_ptr = CardTableModRefBS::dirty_card_val();
2775 _dcq.enqueue(card_ptr);
2776 }
2777 }
2778 }
2779 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2780 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2781 hrrs.n_yielded(), r->rem_set()->occupied());
2782 r->rem_set()->clear_locked();
2783 }
2784 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2785 }
2786 _total_humongous++;
2787
2788 return false;
2789 }
2790
2791 size_t total_humongous() const { return _total_humongous; }
2792 size_t candidate_humongous() const { return _candidate_humongous; }
2793
2794 void flush_rem_set_entries() { _dcq.flush(); }
2795 };
2796
2797 void G1CollectedHeap::register_humongous_regions_with_cset() {
2798 if (!G1EagerReclaimHumongousObjects) {
2799 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2800 return;
2801 }
2802 double time = os::elapsed_counter();
2803
2804 // Collect reclaim candidate information and register candidates with cset.
2805 RegisterHumongousWithInCSetFastTestClosure cl;
2806 heap_region_iterate(&cl);
2807
2808 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2809 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2810 cl.total_humongous(),
2811 cl.candidate_humongous());
2812 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2813
2814 // Finally flush all remembered set entries to re-check into the global DCQS.
2815 cl.flush_rem_set_entries();
2816 }
2817
2818 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2819 public:
2820 bool doHeapRegion(HeapRegion* hr) {
2821 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2822 hr->verify_rem_set();
2823 }
2824 return false;
2825 }
2826 };
2827
2828 uint G1CollectedHeap::num_task_queues() const {
2829 return _task_queues->size();
2830 }
2831
2832 #if TASKQUEUE_STATS
2833 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2834 st->print_raw_cr("GC Task Stats");
2835 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2836 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2837 }
2838
2839 void G1CollectedHeap::print_taskqueue_stats() const {
2840 if (!log_is_enabled(Trace, gc, task, stats)) {
2841 return;
2842 }
2843 Log(gc, task, stats) log;
2844 ResourceMark rm;
2845 LogStream ls(log.trace());
2846 outputStream* st = &ls;
2847
2848 print_taskqueue_stats_hdr(st);
2849
2850 TaskQueueStats totals;
2851 const uint n = num_task_queues();
2852 for (uint i = 0; i < n; ++i) {
2853 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2854 totals += task_queue(i)->stats;
2855 }
2856 st->print_raw("tot "); totals.print(st); st->cr();
2857
2858 DEBUG_ONLY(totals.verify());
2859 }
2860
2861 void G1CollectedHeap::reset_taskqueue_stats() {
2862 const uint n = num_task_queues();
2863 for (uint i = 0; i < n; ++i) {
2864 task_queue(i)->stats.reset();
2865 }
2866 }
2867 #endif // TASKQUEUE_STATS
2868
2869 void G1CollectedHeap::wait_for_root_region_scanning() {
2870 double scan_wait_start = os::elapsedTime();
2871 // We have to wait until the CM threads finish scanning the
2872 // root regions as it's the only way to ensure that all the
2873 // objects on them have been correctly scanned before we start
2874 // moving them during the GC.
2875 bool waited = _cm->root_regions()->wait_until_scan_finished();
2876 double wait_time_ms = 0.0;
2877 if (waited) {
2878 double scan_wait_end = os::elapsedTime();
2879 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2880 }
2881 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2882 }
2883
2884 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2885 private:
2886 G1HRPrinter* _hr_printer;
2887 public:
2888 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2889
2890 virtual bool doHeapRegion(HeapRegion* r) {
2891 _hr_printer->cset(r);
2892 return false;
2893 }
2894 };
2895
2896 void G1CollectedHeap::start_new_collection_set() {
2897 collection_set()->start_incremental_building();
2898
2899 clear_cset_fast_test();
2900
2901 guarantee(_eden.length() == 0, "eden should have been cleared");
2902 g1_policy()->transfer_survivors_to_cset(survivor());
2903 }
2904
2905 bool
2906 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2907 assert_at_safepoint(true /* should_be_vm_thread */);
2908 guarantee(!is_gc_active(), "collection is not reentrant");
2909
2910 if (GCLocker::check_active_before_gc()) {
2911 return false;
2912 }
2913
2914 _gc_timer_stw->register_gc_start();
2915
2916 GCIdMark gc_id_mark;
2917 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2918
2919 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2920 ResourceMark rm;
2921
2922 g1_policy()->note_gc_start();
2923
2924 wait_for_root_region_scanning();
2925
2926 print_heap_before_gc();
2927 print_heap_regions();
2928 trace_heap_before_gc(_gc_tracer_stw);
2929
2930 _verifier->verify_region_sets_optional();
2931 _verifier->verify_dirty_young_regions();
2932
2933 // We should not be doing initial mark unless the conc mark thread is running
2934 if (!_cmThread->should_terminate()) {
2935 // This call will decide whether this pause is an initial-mark
2936 // pause. If it is, during_initial_mark_pause() will return true
2937 // for the duration of this pause.
2938 g1_policy()->decide_on_conc_mark_initiation();
2939 }
2940
2941 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2942 assert(!collector_state()->during_initial_mark_pause() ||
2943 collector_state()->gcs_are_young(), "sanity");
2944
2945 // We also do not allow mixed GCs during marking.
2946 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2947
2948 // Record whether this pause is an initial mark. When the current
2949 // thread has completed its logging output and it's safe to signal
2950 // the CM thread, the flag's value in the policy has been reset.
2951 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2952
2953 // Inner scope for scope based logging, timers, and stats collection
2954 {
2955 EvacuationInfo evacuation_info;
2956
2957 if (collector_state()->during_initial_mark_pause()) {
2958 // We are about to start a marking cycle, so we increment the
2959 // full collection counter.
2960 increment_old_marking_cycles_started();
2961 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2962 }
2963
2964 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2965
2966 GCTraceCPUTime tcpu;
2967
2968 FormatBuffer<> gc_string("Pause ");
2969 if (collector_state()->during_initial_mark_pause()) {
2970 gc_string.append("Initial Mark");
2971 } else if (collector_state()->gcs_are_young()) {
2972 gc_string.append("Young");
2973 } else {
2974 gc_string.append("Mixed");
2975 }
2976 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2977
2978 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2979 workers()->active_workers(),
2980 Threads::number_of_non_daemon_threads());
2981 workers()->update_active_workers(active_workers);
2982 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2983
2984 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2985 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2986
2987 // If the secondary_free_list is not empty, append it to the
2988 // free_list. No need to wait for the cleanup operation to finish;
2989 // the region allocation code will check the secondary_free_list
2990 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2991 // set, skip this step so that the region allocation code has to
2992 // get entries from the secondary_free_list.
2993 if (!G1StressConcRegionFreeing) {
2994 append_secondary_free_list_if_not_empty_with_lock();
2995 }
2996
2997 G1HeapTransition heap_transition(this);
2998 size_t heap_used_bytes_before_gc = used();
2999
3000 // Don't dynamically change the number of GC threads this early. A value of
3001 // 0 is used to indicate serial work. When parallel work is done,
3002 // it will be set.
3003
3004 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3005 IsGCActiveMark x;
3006
3007 gc_prologue(false);
3008
3009 if (VerifyRememberedSets) {
3010 log_info(gc, verify)("[Verifying RemSets before GC]");
3011 VerifyRegionRemSetClosure v_cl;
3012 heap_region_iterate(&v_cl);
3013 }
3014
3015 _verifier->verify_before_gc();
3016
3017 _verifier->check_bitmaps("GC Start");
3018
3019 #if COMPILER2_OR_JVMCI
3020 DerivedPointerTable::clear();
3021 #endif
3022
3023 // Please see comment in g1CollectedHeap.hpp and
3024 // G1CollectedHeap::ref_processing_init() to see how
3025 // reference processing currently works in G1.
3026
3027 // Enable discovery in the STW reference processor
3028 if (g1_policy()->should_process_references()) {
3029 ref_processor_stw()->enable_discovery();
3030 } else {
3031 ref_processor_stw()->disable_discovery();
3032 }
3033
3034 {
3035 // We want to temporarily turn off discovery by the
3036 // CM ref processor, if necessary, and turn it back on
3037 // on again later if we do. Using a scoped
3038 // NoRefDiscovery object will do this.
3039 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3040
3041 // Forget the current alloc region (we might even choose it to be part
3042 // of the collection set!).
3043 _allocator->release_mutator_alloc_region();
3044
3045 // This timing is only used by the ergonomics to handle our pause target.
3046 // It is unclear why this should not include the full pause. We will
3047 // investigate this in CR 7178365.
3048 //
3049 // Preserving the old comment here if that helps the investigation:
3050 //
3051 // The elapsed time induced by the start time below deliberately elides
3052 // the possible verification above.
3053 double sample_start_time_sec = os::elapsedTime();
3054
3055 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3056
3057 if (collector_state()->during_initial_mark_pause()) {
3058 concurrent_mark()->checkpoint_roots_initial_pre();
3059 }
3060
3061 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3062
3063 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3064
3065 // Make sure the remembered sets are up to date. This needs to be
3066 // done before register_humongous_regions_with_cset(), because the
3067 // remembered sets are used there to choose eager reclaim candidates.
3068 // If the remembered sets are not up to date we might miss some
3069 // entries that need to be handled.
3070 g1_rem_set()->cleanupHRRS();
3071
3072 register_humongous_regions_with_cset();
3073
3074 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3075
3076 // We call this after finalize_cset() to
3077 // ensure that the CSet has been finalized.
3078 _cm->verify_no_cset_oops();
3079
3080 if (_hr_printer.is_active()) {
3081 G1PrintCollectionSetClosure cl(&_hr_printer);
3082 _collection_set.iterate(&cl);
3083 }
3084
3085 // Initialize the GC alloc regions.
3086 _allocator->init_gc_alloc_regions(evacuation_info);
3087
3088 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3089 pre_evacuate_collection_set();
3090
3091 // Actually do the work...
3092 evacuate_collection_set(evacuation_info, &per_thread_states);
3093
3094 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3095
3096 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3097 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3098
3099 eagerly_reclaim_humongous_regions();
3100
3101 record_obj_copy_mem_stats();
3102 _survivor_evac_stats.adjust_desired_plab_sz();
3103 _old_evac_stats.adjust_desired_plab_sz();
3104
3105 double start = os::elapsedTime();
3106 start_new_collection_set();
3107 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3108
3109 if (evacuation_failed()) {
3110 set_used(recalculate_used());
3111 if (_archive_allocator != NULL) {
3112 _archive_allocator->clear_used();
3113 }
3114 for (uint i = 0; i < ParallelGCThreads; i++) {
3115 if (_evacuation_failed_info_array[i].has_failed()) {
3116 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3117 }
3118 }
3119 } else {
3120 // The "used" of the the collection set have already been subtracted
3121 // when they were freed. Add in the bytes evacuated.
3122 increase_used(g1_policy()->bytes_copied_during_gc());
3123 }
3124
3125 if (collector_state()->during_initial_mark_pause()) {
3126 // We have to do this before we notify the CM threads that
3127 // they can start working to make sure that all the
3128 // appropriate initialization is done on the CM object.
3129 concurrent_mark()->checkpoint_roots_initial_post();
3130 collector_state()->set_mark_in_progress(true);
3131 // Note that we don't actually trigger the CM thread at
3132 // this point. We do that later when we're sure that
3133 // the current thread has completed its logging output.
3134 }
3135
3136 allocate_dummy_regions();
3137
3138 _allocator->init_mutator_alloc_region();
3139
3140 {
3141 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3142 if (expand_bytes > 0) {
3143 size_t bytes_before = capacity();
3144 // No need for an ergo logging here,
3145 // expansion_amount() does this when it returns a value > 0.
3146 double expand_ms;
3147 if (!expand(expand_bytes, _workers, &expand_ms)) {
3148 // We failed to expand the heap. Cannot do anything about it.
3149 }
3150 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3151 }
3152 }
3153
3154 // We redo the verification but now wrt to the new CSet which
3155 // has just got initialized after the previous CSet was freed.
3156 _cm->verify_no_cset_oops();
3157
3158 // This timing is only used by the ergonomics to handle our pause target.
3159 // It is unclear why this should not include the full pause. We will
3160 // investigate this in CR 7178365.
3161 double sample_end_time_sec = os::elapsedTime();
3162 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3163 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3164 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3165
3166 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3167 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3168
3169 if (VerifyRememberedSets) {
3170 log_info(gc, verify)("[Verifying RemSets after GC]");
3171 VerifyRegionRemSetClosure v_cl;
3172 heap_region_iterate(&v_cl);
3173 }
3174
3175 _verifier->verify_after_gc();
3176 _verifier->check_bitmaps("GC End");
3177
3178 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3179 ref_processor_stw()->verify_no_references_recorded();
3180
3181 // CM reference discovery will be re-enabled if necessary.
3182 }
3183
3184 #ifdef TRACESPINNING
3185 ParallelTaskTerminator::print_termination_counts();
3186 #endif
3187
3188 gc_epilogue(false);
3189 }
3190
3191 // Print the remainder of the GC log output.
3192 if (evacuation_failed()) {
3193 log_info(gc)("To-space exhausted");
3194 }
3195
3196 g1_policy()->print_phases();
3197 heap_transition.print();
3198
3199 // It is not yet to safe to tell the concurrent mark to
3200 // start as we have some optional output below. We don't want the
3201 // output from the concurrent mark thread interfering with this
3202 // logging output either.
3203
3204 _hrm.verify_optional();
3205 _verifier->verify_region_sets_optional();
3206
3207 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3208 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3209
3210 print_heap_after_gc();
3211 print_heap_regions();
3212 trace_heap_after_gc(_gc_tracer_stw);
3213
3214 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3215 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3216 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3217 // before any GC notifications are raised.
3218 g1mm()->update_sizes();
3219
3220 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3221 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3222 _gc_timer_stw->register_gc_end();
3223 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3224 }
3225 // It should now be safe to tell the concurrent mark thread to start
3226 // without its logging output interfering with the logging output
3227 // that came from the pause.
3228
3229 if (should_start_conc_mark) {
3230 // CAUTION: after the doConcurrentMark() call below,
3231 // the concurrent marking thread(s) could be running
3232 // concurrently with us. Make sure that anything after
3233 // this point does not assume that we are the only GC thread
3234 // running. Note: of course, the actual marking work will
3235 // not start until the safepoint itself is released in
3236 // SuspendibleThreadSet::desynchronize().
3237 doConcurrentMark();
3238 }
3239
3240 return true;
3241 }
3242
3243 void G1CollectedHeap::remove_self_forwarding_pointers() {
3244 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3245 workers()->run_task(&rsfp_task);
3246 }
3247
3248 void G1CollectedHeap::restore_after_evac_failure() {
3249 double remove_self_forwards_start = os::elapsedTime();
3250
3251 remove_self_forwarding_pointers();
3252 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3253 _preserved_marks_set.restore(&task_executor);
3254
3255 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3256 }
3257
3258 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3259 if (!_evacuation_failed) {
3260 _evacuation_failed = true;
3261 }
3262
3263 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3264 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3265 }
3266
3267 bool G1ParEvacuateFollowersClosure::offer_termination() {
3268 G1ParScanThreadState* const pss = par_scan_state();
3269 start_term_time();
3270 const bool res = terminator()->offer_termination();
3271 end_term_time();
3272 return res;
3273 }
3274
3275 void G1ParEvacuateFollowersClosure::do_void() {
3276 G1ParScanThreadState* const pss = par_scan_state();
3277 pss->trim_queue();
3278 do {
3279 pss->steal_and_trim_queue(queues());
3280 } while (!offer_termination());
3281 }
3282
3283 class G1ParTask : public AbstractGangTask {
3284 protected:
3285 G1CollectedHeap* _g1h;
3286 G1ParScanThreadStateSet* _pss;
3287 RefToScanQueueSet* _queues;
3288 G1RootProcessor* _root_processor;
3289 ParallelTaskTerminator _terminator;
3290 uint _n_workers;
3291
3292 public:
3293 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3294 : AbstractGangTask("G1 collection"),
3295 _g1h(g1h),
3296 _pss(per_thread_states),
3297 _queues(task_queues),
3298 _root_processor(root_processor),
3299 _terminator(n_workers, _queues),
3300 _n_workers(n_workers)
3301 {}
3302
3303 void work(uint worker_id) {
3304 if (worker_id >= _n_workers) return; // no work needed this round
3305
3306 double start_sec = os::elapsedTime();
3307 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3308
3309 {
3310 ResourceMark rm;
3311 HandleMark hm;
3312
3313 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3314
3315 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3316 pss->set_ref_processor(rp);
3317
3318 double start_strong_roots_sec = os::elapsedTime();
3319
3320 _root_processor->evacuate_roots(pss->closures(), worker_id);
3321
3322 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3323 // treating the nmethods visited to act as roots for concurrent marking.
3324 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3325 // objects copied by the current evacuation.
3326 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3327 pss->closures()->weak_codeblobs(),
3328 worker_id);
3329
3330 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3331
3332 double term_sec = 0.0;
3333 size_t evac_term_attempts = 0;
3334 {
3335 double start = os::elapsedTime();
3336 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3337 evac.do_void();
3338
3339 evac_term_attempts = evac.term_attempts();
3340 term_sec = evac.term_time();
3341 double elapsed_sec = os::elapsedTime() - start;
3342 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3343 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3344 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3345 }
3346
3347 assert(pss->queue_is_empty(), "should be empty");
3348
3349 if (log_is_enabled(Debug, gc, task, stats)) {
3350 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3351 size_t lab_waste;
3352 size_t lab_undo_waste;
3353 pss->waste(lab_waste, lab_undo_waste);
3354 _g1h->print_termination_stats(worker_id,
3355 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3356 strong_roots_sec * 1000.0, /* strong roots time */
3357 term_sec * 1000.0, /* evac term time */
3358 evac_term_attempts, /* evac term attempts */
3359 lab_waste, /* alloc buffer waste */
3360 lab_undo_waste /* undo waste */
3361 );
3362 }
3363
3364 // Close the inner scope so that the ResourceMark and HandleMark
3365 // destructors are executed here and are included as part of the
3366 // "GC Worker Time".
3367 }
3368 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3369 }
3370 };
3371
3372 void G1CollectedHeap::print_termination_stats_hdr() {
3373 log_debug(gc, task, stats)("GC Termination Stats");
3374 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3375 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3376 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3377 }
3378
3379 void G1CollectedHeap::print_termination_stats(uint worker_id,
3380 double elapsed_ms,
3381 double strong_roots_ms,
3382 double term_ms,
3383 size_t term_attempts,
3384 size_t alloc_buffer_waste,
3385 size_t undo_waste) const {
3386 log_debug(gc, task, stats)
3387 ("%3d %9.2f %9.2f %6.2f "
3388 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3389 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3390 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3391 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3392 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3393 alloc_buffer_waste * HeapWordSize / K,
3394 undo_waste * HeapWordSize / K);
3395 }
3396
3397 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3398 private:
3399 BoolObjectClosure* _is_alive;
3400 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3401
3402 int _initial_string_table_size;
3403 int _initial_symbol_table_size;
3404
3405 bool _process_strings;
3406 int _strings_processed;
3407 int _strings_removed;
3408
3409 bool _process_symbols;
3410 int _symbols_processed;
3411 int _symbols_removed;
3412
3413 bool _process_string_dedup;
3414
3415 public:
3416 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3417 AbstractGangTask("String/Symbol Unlinking"),
3418 _is_alive(is_alive),
3419 _dedup_closure(is_alive, NULL, false),
3420 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3421 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3422 _process_string_dedup(process_string_dedup) {
3423
3424 _initial_string_table_size = StringTable::the_table()->table_size();
3425 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3426 if (process_strings) {
3427 StringTable::clear_parallel_claimed_index();
3428 }
3429 if (process_symbols) {
3430 SymbolTable::clear_parallel_claimed_index();
3431 }
3432 }
3433
3434 ~G1StringAndSymbolCleaningTask() {
3435 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3436 "claim value %d after unlink less than initial string table size %d",
3437 StringTable::parallel_claimed_index(), _initial_string_table_size);
3438 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3439 "claim value %d after unlink less than initial symbol table size %d",
3440 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3441
3442 log_info(gc, stringtable)(
3443 "Cleaned string and symbol table, "
3444 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3445 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3446 strings_processed(), strings_removed(),
3447 symbols_processed(), symbols_removed());
3448 }
3449
3450 void work(uint worker_id) {
3451 int strings_processed = 0;
3452 int strings_removed = 0;
3453 int symbols_processed = 0;
3454 int symbols_removed = 0;
3455 if (_process_strings) {
3456 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3457 Atomic::add(strings_processed, &_strings_processed);
3458 Atomic::add(strings_removed, &_strings_removed);
3459 }
3460 if (_process_symbols) {
3461 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3462 Atomic::add(symbols_processed, &_symbols_processed);
3463 Atomic::add(symbols_removed, &_symbols_removed);
3464 }
3465 if (_process_string_dedup) {
3466 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3467 }
3468 }
3469
3470 size_t strings_processed() const { return (size_t)_strings_processed; }
3471 size_t strings_removed() const { return (size_t)_strings_removed; }
3472
3473 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3474 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3475 };
3476
3477 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3478 private:
3479 static Monitor* _lock;
3480
3481 BoolObjectClosure* const _is_alive;
3482 const bool _unloading_occurred;
3483 const uint _num_workers;
3484
3485 // Variables used to claim nmethods.
3486 CompiledMethod* _first_nmethod;
3487 CompiledMethod* volatile _claimed_nmethod;
3488
3489 // The list of nmethods that need to be processed by the second pass.
3490 CompiledMethod* volatile _postponed_list;
3491 volatile uint _num_entered_barrier;
3492
3493 public:
3494 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3495 _is_alive(is_alive),
3496 _unloading_occurred(unloading_occurred),
3497 _num_workers(num_workers),
3498 _first_nmethod(NULL),
3499 _claimed_nmethod(NULL),
3500 _postponed_list(NULL),
3501 _num_entered_barrier(0)
3502 {
3503 CompiledMethod::increase_unloading_clock();
3504 // Get first alive nmethod
3505 CompiledMethodIterator iter = CompiledMethodIterator();
3506 if(iter.next_alive()) {
3507 _first_nmethod = iter.method();
3508 }
3509 _claimed_nmethod = _first_nmethod;
3510 }
3511
3512 ~G1CodeCacheUnloadingTask() {
3513 CodeCache::verify_clean_inline_caches();
3514
3515 CodeCache::set_needs_cache_clean(false);
3516 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3517
3518 CodeCache::verify_icholder_relocations();
3519 }
3520
3521 private:
3522 void add_to_postponed_list(CompiledMethod* nm) {
3523 CompiledMethod* old;
3524 do {
3525 old = _postponed_list;
3526 nm->set_unloading_next(old);
3527 } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
3528 }
3529
3530 void clean_nmethod(CompiledMethod* nm) {
3531 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3532
3533 if (postponed) {
3534 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3535 add_to_postponed_list(nm);
3536 }
3537
3538 // Mark that this thread has been cleaned/unloaded.
3539 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3540 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3541 }
3542
3543 void clean_nmethod_postponed(CompiledMethod* nm) {
3544 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3545 }
3546
3547 static const int MaxClaimNmethods = 16;
3548
3549 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3550 CompiledMethod* first;
3551 CompiledMethodIterator last;
3552
3553 do {
3554 *num_claimed_nmethods = 0;
3555
3556 first = _claimed_nmethod;
3557 last = CompiledMethodIterator(first);
3558
3559 if (first != NULL) {
3560
3561 for (int i = 0; i < MaxClaimNmethods; i++) {
3562 if (!last.next_alive()) {
3563 break;
3564 }
3565 claimed_nmethods[i] = last.method();
3566 (*num_claimed_nmethods)++;
3567 }
3568 }
3569
3570 } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
3571 }
3572
3573 CompiledMethod* claim_postponed_nmethod() {
3574 CompiledMethod* claim;
3575 CompiledMethod* next;
3576
3577 do {
3578 claim = _postponed_list;
3579 if (claim == NULL) {
3580 return NULL;
3581 }
3582
3583 next = claim->unloading_next();
3584
3585 } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
3586
3587 return claim;
3588 }
3589
3590 public:
3591 // Mark that we're done with the first pass of nmethod cleaning.
3592 void barrier_mark(uint worker_id) {
3593 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3594 _num_entered_barrier++;
3595 if (_num_entered_barrier == _num_workers) {
3596 ml.notify_all();
3597 }
3598 }
3599
3600 // See if we have to wait for the other workers to
3601 // finish their first-pass nmethod cleaning work.
3602 void barrier_wait(uint worker_id) {
3603 if (_num_entered_barrier < _num_workers) {
3604 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3605 while (_num_entered_barrier < _num_workers) {
3606 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3607 }
3608 }
3609 }
3610
3611 // Cleaning and unloading of nmethods. Some work has to be postponed
3612 // to the second pass, when we know which nmethods survive.
3613 void work_first_pass(uint worker_id) {
3614 // The first nmethods is claimed by the first worker.
3615 if (worker_id == 0 && _first_nmethod != NULL) {
3616 clean_nmethod(_first_nmethod);
3617 _first_nmethod = NULL;
3618 }
3619
3620 int num_claimed_nmethods;
3621 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3622
3623 while (true) {
3624 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3625
3626 if (num_claimed_nmethods == 0) {
3627 break;
3628 }
3629
3630 for (int i = 0; i < num_claimed_nmethods; i++) {
3631 clean_nmethod(claimed_nmethods[i]);
3632 }
3633 }
3634 }
3635
3636 void work_second_pass(uint worker_id) {
3637 CompiledMethod* nm;
3638 // Take care of postponed nmethods.
3639 while ((nm = claim_postponed_nmethod()) != NULL) {
3640 clean_nmethod_postponed(nm);
3641 }
3642 }
3643 };
3644
3645 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3646
3647 class G1KlassCleaningTask : public StackObj {
3648 BoolObjectClosure* _is_alive;
3649 volatile int _clean_klass_tree_claimed;
3650 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3651
3652 public:
3653 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3654 _is_alive(is_alive),
3655 _clean_klass_tree_claimed(0),
3656 _klass_iterator() {
3657 }
3658
3659 private:
3660 bool claim_clean_klass_tree_task() {
3661 if (_clean_klass_tree_claimed) {
3662 return false;
3663 }
3664
3665 return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
3666 }
3667
3668 InstanceKlass* claim_next_klass() {
3669 Klass* klass;
3670 do {
3671 klass =_klass_iterator.next_klass();
3672 } while (klass != NULL && !klass->is_instance_klass());
3673
3674 // this can be null so don't call InstanceKlass::cast
3675 return static_cast<InstanceKlass*>(klass);
3676 }
3677
3678 public:
3679
3680 void clean_klass(InstanceKlass* ik) {
3681 ik->clean_weak_instanceklass_links(_is_alive);
3682 }
3683
3684 void work() {
3685 ResourceMark rm;
3686
3687 // One worker will clean the subklass/sibling klass tree.
3688 if (claim_clean_klass_tree_task()) {
3689 Klass::clean_subklass_tree(_is_alive);
3690 }
3691
3692 // All workers will help cleaning the classes,
3693 InstanceKlass* klass;
3694 while ((klass = claim_next_klass()) != NULL) {
3695 clean_klass(klass);
3696 }
3697 }
3698 };
3699
3700 class G1ResolvedMethodCleaningTask : public StackObj {
3701 BoolObjectClosure* _is_alive;
3702 volatile int _resolved_method_task_claimed;
3703 public:
3704 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3705 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3706
3707 bool claim_resolved_method_task() {
3708 if (_resolved_method_task_claimed) {
3709 return false;
3710 }
3711 return Atomic::cmpxchg(1, &_resolved_method_task_claimed, 0) == 0;
3712 }
3713
3714 // These aren't big, one thread can do it all.
3715 void work() {
3716 if (claim_resolved_method_task()) {
3717 ResolvedMethodTable::unlink(_is_alive);
3718 }
3719 }
3720 };
3721
3722
3723 // To minimize the remark pause times, the tasks below are done in parallel.
3724 class G1ParallelCleaningTask : public AbstractGangTask {
3725 private:
3726 G1StringAndSymbolCleaningTask _string_symbol_task;
3727 G1CodeCacheUnloadingTask _code_cache_task;
3728 G1KlassCleaningTask _klass_cleaning_task;
3729 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3730
3731 public:
3732 // The constructor is run in the VMThread.
3733 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3734 AbstractGangTask("Parallel Cleaning"),
3735 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3736 _code_cache_task(num_workers, is_alive, unloading_occurred),
3737 _klass_cleaning_task(is_alive),
3738 _resolved_method_cleaning_task(is_alive) {
3739 }
3740
3741 // The parallel work done by all worker threads.
3742 void work(uint worker_id) {
3743 // Do first pass of code cache cleaning.
3744 _code_cache_task.work_first_pass(worker_id);
3745
3746 // Let the threads mark that the first pass is done.
3747 _code_cache_task.barrier_mark(worker_id);
3748
3749 // Clean the Strings and Symbols.
3750 _string_symbol_task.work(worker_id);
3751
3752 // Clean unreferenced things in the ResolvedMethodTable
3753 _resolved_method_cleaning_task.work();
3754
3755 // Wait for all workers to finish the first code cache cleaning pass.
3756 _code_cache_task.barrier_wait(worker_id);
3757
3758 // Do the second code cache cleaning work, which realize on
3759 // the liveness information gathered during the first pass.
3760 _code_cache_task.work_second_pass(worker_id);
3761
3762 // Clean all klasses that were not unloaded.
3763 _klass_cleaning_task.work();
3764 }
3765 };
3766
3767
3768 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3769 bool class_unloading_occurred) {
3770 uint n_workers = workers()->active_workers();
3771
3772 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3773 workers()->run_task(&g1_unlink_task);
3774 }
3775
3776 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3777 bool process_strings,
3778 bool process_symbols,
3779 bool process_string_dedup) {
3780 if (!process_strings && !process_symbols && !process_string_dedup) {
3781 // Nothing to clean.
3782 return;
3783 }
3784
3785 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3786 workers()->run_task(&g1_unlink_task);
3787
3788 }
3789
3790 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3791 private:
3792 DirtyCardQueueSet* _queue;
3793 G1CollectedHeap* _g1h;
3794 public:
3795 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3796 _queue(queue), _g1h(g1h) { }
3797
3798 virtual void work(uint worker_id) {
3799 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3800 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3801
3802 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3803 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3804
3805 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3806 }
3807 };
3808
3809 void G1CollectedHeap::redirty_logged_cards() {
3810 double redirty_logged_cards_start = os::elapsedTime();
3811
3812 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3813 dirty_card_queue_set().reset_for_par_iteration();
3814 workers()->run_task(&redirty_task);
3815
3816 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3817 dcq.merge_bufferlists(&dirty_card_queue_set());
3818 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3819
3820 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3821 }
3822
3823 // Weak Reference Processing support
3824
3825 // An always "is_alive" closure that is used to preserve referents.
3826 // If the object is non-null then it's alive. Used in the preservation
3827 // of referent objects that are pointed to by reference objects
3828 // discovered by the CM ref processor.
3829 class G1AlwaysAliveClosure: public BoolObjectClosure {
3830 G1CollectedHeap* _g1;
3831 public:
3832 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3833 bool do_object_b(oop p) {
3834 if (p != NULL) {
3835 return true;
3836 }
3837 return false;
3838 }
3839 };
3840
3841 bool G1STWIsAliveClosure::do_object_b(oop p) {
3842 // An object is reachable if it is outside the collection set,
3843 // or is inside and copied.
3844 return !_g1->is_in_cset(p) || p->is_forwarded();
3845 }
3846
3847 // Non Copying Keep Alive closure
3848 class G1KeepAliveClosure: public OopClosure {
3849 G1CollectedHeap* _g1;
3850 public:
3851 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3852 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3853 void do_oop(oop* p) {
3854 oop obj = *p;
3855 assert(obj != NULL, "the caller should have filtered out NULL values");
3856
3857 const InCSetState cset_state = _g1->in_cset_state(obj);
3858 if (!cset_state.is_in_cset_or_humongous()) {
3859 return;
3860 }
3861 if (cset_state.is_in_cset()) {
3862 assert( obj->is_forwarded(), "invariant" );
3863 *p = obj->forwardee();
3864 } else {
3865 assert(!obj->is_forwarded(), "invariant" );
3866 assert(cset_state.is_humongous(),
3867 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3868 _g1->set_humongous_is_live(obj);
3869 }
3870 }
3871 };
3872
3873 // Copying Keep Alive closure - can be called from both
3874 // serial and parallel code as long as different worker
3875 // threads utilize different G1ParScanThreadState instances
3876 // and different queues.
3877
3878 class G1CopyingKeepAliveClosure: public OopClosure {
3879 G1CollectedHeap* _g1h;
3880 OopClosure* _copy_non_heap_obj_cl;
3881 G1ParScanThreadState* _par_scan_state;
3882
3883 public:
3884 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3885 OopClosure* non_heap_obj_cl,
3886 G1ParScanThreadState* pss):
3887 _g1h(g1h),
3888 _copy_non_heap_obj_cl(non_heap_obj_cl),
3889 _par_scan_state(pss)
3890 {}
3891
3892 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3893 virtual void do_oop( oop* p) { do_oop_work(p); }
3894
3895 template <class T> void do_oop_work(T* p) {
3896 oop obj = oopDesc::load_decode_heap_oop(p);
3897
3898 if (_g1h->is_in_cset_or_humongous(obj)) {
3899 // If the referent object has been forwarded (either copied
3900 // to a new location or to itself in the event of an
3901 // evacuation failure) then we need to update the reference
3902 // field and, if both reference and referent are in the G1
3903 // heap, update the RSet for the referent.
3904 //
3905 // If the referent has not been forwarded then we have to keep
3906 // it alive by policy. Therefore we have copy the referent.
3907 //
3908 // If the reference field is in the G1 heap then we can push
3909 // on the PSS queue. When the queue is drained (after each
3910 // phase of reference processing) the object and it's followers
3911 // will be copied, the reference field set to point to the
3912 // new location, and the RSet updated. Otherwise we need to
3913 // use the the non-heap or metadata closures directly to copy
3914 // the referent object and update the pointer, while avoiding
3915 // updating the RSet.
3916
3917 if (_g1h->is_in_g1_reserved(p)) {
3918 _par_scan_state->push_on_queue(p);
3919 } else {
3920 assert(!Metaspace::contains((const void*)p),
3921 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3922 _copy_non_heap_obj_cl->do_oop(p);
3923 }
3924 }
3925 }
3926 };
3927
3928 // Serial drain queue closure. Called as the 'complete_gc'
3929 // closure for each discovered list in some of the
3930 // reference processing phases.
3931
3932 class G1STWDrainQueueClosure: public VoidClosure {
3933 protected:
3934 G1CollectedHeap* _g1h;
3935 G1ParScanThreadState* _par_scan_state;
3936
3937 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3938
3939 public:
3940 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3941 _g1h(g1h),
3942 _par_scan_state(pss)
3943 { }
3944
3945 void do_void() {
3946 G1ParScanThreadState* const pss = par_scan_state();
3947 pss->trim_queue();
3948 }
3949 };
3950
3951 // Parallel Reference Processing closures
3952
3953 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3954 // processing during G1 evacuation pauses.
3955
3956 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3957 private:
3958 G1CollectedHeap* _g1h;
3959 G1ParScanThreadStateSet* _pss;
3960 RefToScanQueueSet* _queues;
3961 WorkGang* _workers;
3962 uint _active_workers;
3963
3964 public:
3965 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3966 G1ParScanThreadStateSet* per_thread_states,
3967 WorkGang* workers,
3968 RefToScanQueueSet *task_queues,
3969 uint n_workers) :
3970 _g1h(g1h),
3971 _pss(per_thread_states),
3972 _queues(task_queues),
3973 _workers(workers),
3974 _active_workers(n_workers)
3975 {
3976 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3977 }
3978
3979 // Executes the given task using concurrent marking worker threads.
3980 virtual void execute(ProcessTask& task);
3981 virtual void execute(EnqueueTask& task);
3982 };
3983
3984 // Gang task for possibly parallel reference processing
3985
3986 class G1STWRefProcTaskProxy: public AbstractGangTask {
3987 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3988 ProcessTask& _proc_task;
3989 G1CollectedHeap* _g1h;
3990 G1ParScanThreadStateSet* _pss;
3991 RefToScanQueueSet* _task_queues;
3992 ParallelTaskTerminator* _terminator;
3993
3994 public:
3995 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3996 G1CollectedHeap* g1h,
3997 G1ParScanThreadStateSet* per_thread_states,
3998 RefToScanQueueSet *task_queues,
3999 ParallelTaskTerminator* terminator) :
4000 AbstractGangTask("Process reference objects in parallel"),
4001 _proc_task(proc_task),
4002 _g1h(g1h),
4003 _pss(per_thread_states),
4004 _task_queues(task_queues),
4005 _terminator(terminator)
4006 {}
4007
4008 virtual void work(uint worker_id) {
4009 // The reference processing task executed by a single worker.
4010 ResourceMark rm;
4011 HandleMark hm;
4012
4013 G1STWIsAliveClosure is_alive(_g1h);
4014
4015 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4016 pss->set_ref_processor(NULL);
4017
4018 // Keep alive closure.
4019 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4020
4021 // Complete GC closure
4022 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4023
4024 // Call the reference processing task's work routine.
4025 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4026
4027 // Note we cannot assert that the refs array is empty here as not all
4028 // of the processing tasks (specifically phase2 - pp2_work) execute
4029 // the complete_gc closure (which ordinarily would drain the queue) so
4030 // the queue may not be empty.
4031 }
4032 };
4033
4034 // Driver routine for parallel reference processing.
4035 // Creates an instance of the ref processing gang
4036 // task and has the worker threads execute it.
4037 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4038 assert(_workers != NULL, "Need parallel worker threads.");
4039
4040 ParallelTaskTerminator terminator(_active_workers, _queues);
4041 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4042
4043 _workers->run_task(&proc_task_proxy);
4044 }
4045
4046 // Gang task for parallel reference enqueueing.
4047
4048 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4049 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4050 EnqueueTask& _enq_task;
4051
4052 public:
4053 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4054 AbstractGangTask("Enqueue reference objects in parallel"),
4055 _enq_task(enq_task)
4056 { }
4057
4058 virtual void work(uint worker_id) {
4059 _enq_task.work(worker_id);
4060 }
4061 };
4062
4063 // Driver routine for parallel reference enqueueing.
4064 // Creates an instance of the ref enqueueing gang
4065 // task and has the worker threads execute it.
4066
4067 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4068 assert(_workers != NULL, "Need parallel worker threads.");
4069
4070 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4071
4072 _workers->run_task(&enq_task_proxy);
4073 }
4074
4075 // End of weak reference support closures
4076
4077 // Abstract task used to preserve (i.e. copy) any referent objects
4078 // that are in the collection set and are pointed to by reference
4079 // objects discovered by the CM ref processor.
4080
4081 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4082 protected:
4083 G1CollectedHeap* _g1h;
4084 G1ParScanThreadStateSet* _pss;
4085 RefToScanQueueSet* _queues;
4086 ParallelTaskTerminator _terminator;
4087 uint _n_workers;
4088
4089 public:
4090 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4091 AbstractGangTask("ParPreserveCMReferents"),
4092 _g1h(g1h),
4093 _pss(per_thread_states),
4094 _queues(task_queues),
4095 _terminator(workers, _queues),
4096 _n_workers(workers)
4097 {
4098 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4099 }
4100
4101 void work(uint worker_id) {
4102 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4103
4104 ResourceMark rm;
4105 HandleMark hm;
4106
4107 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4108 pss->set_ref_processor(NULL);
4109 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4110
4111 // Is alive closure
4112 G1AlwaysAliveClosure always_alive(_g1h);
4113
4114 // Copying keep alive closure. Applied to referent objects that need
4115 // to be copied.
4116 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4117
4118 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4119
4120 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4121 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4122
4123 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4124 // So this must be true - but assert just in case someone decides to
4125 // change the worker ids.
4126 assert(worker_id < limit, "sanity");
4127 assert(!rp->discovery_is_atomic(), "check this code");
4128
4129 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4130 for (uint idx = worker_id; idx < limit; idx += stride) {
4131 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4132
4133 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4134 while (iter.has_next()) {
4135 // Since discovery is not atomic for the CM ref processor, we
4136 // can see some null referent objects.
4137 iter.load_ptrs(DEBUG_ONLY(true));
4138 oop ref = iter.obj();
4139
4140 // This will filter nulls.
4141 if (iter.is_referent_alive()) {
4142 iter.make_referent_alive();
4143 }
4144 iter.move_to_next();
4145 }
4146 }
4147
4148 // Drain the queue - which may cause stealing
4149 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4150 drain_queue.do_void();
4151 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4152 assert(pss->queue_is_empty(), "should be");
4153 }
4154 };
4155
4156 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4157 // Any reference objects, in the collection set, that were 'discovered'
4158 // by the CM ref processor should have already been copied (either by
4159 // applying the external root copy closure to the discovered lists, or
4160 // by following an RSet entry).
4161 //
4162 // But some of the referents, that are in the collection set, that these
4163 // reference objects point to may not have been copied: the STW ref
4164 // processor would have seen that the reference object had already
4165 // been 'discovered' and would have skipped discovering the reference,
4166 // but would not have treated the reference object as a regular oop.
4167 // As a result the copy closure would not have been applied to the
4168 // referent object.
4169 //
4170 // We need to explicitly copy these referent objects - the references
4171 // will be processed at the end of remarking.
4172 //
4173 // We also need to do this copying before we process the reference
4174 // objects discovered by the STW ref processor in case one of these
4175 // referents points to another object which is also referenced by an
4176 // object discovered by the STW ref processor.
4177 double preserve_cm_referents_time = 0.0;
4178
4179 // To avoid spawning task when there is no work to do, check that
4180 // a concurrent cycle is active and that some references have been
4181 // discovered.
4182 if (concurrent_mark()->cm_thread()->during_cycle() &&
4183 ref_processor_cm()->has_discovered_references()) {
4184 double preserve_cm_referents_start = os::elapsedTime();
4185 uint no_of_gc_workers = workers()->active_workers();
4186 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4187 per_thread_states,
4188 no_of_gc_workers,
4189 _task_queues);
4190 workers()->run_task(&keep_cm_referents);
4191 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4192 }
4193
4194 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4195 }
4196
4197 // Weak Reference processing during an evacuation pause (part 1).
4198 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4199 double ref_proc_start = os::elapsedTime();
4200
4201 ReferenceProcessor* rp = _ref_processor_stw;
4202 assert(rp->discovery_enabled(), "should have been enabled");
4203
4204 // Closure to test whether a referent is alive.
4205 G1STWIsAliveClosure is_alive(this);
4206
4207 // Even when parallel reference processing is enabled, the processing
4208 // of JNI refs is serial and performed serially by the current thread
4209 // rather than by a worker. The following PSS will be used for processing
4210 // JNI refs.
4211
4212 // Use only a single queue for this PSS.
4213 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4214 pss->set_ref_processor(NULL);
4215 assert(pss->queue_is_empty(), "pre-condition");
4216
4217 // Keep alive closure.
4218 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4219
4220 // Serial Complete GC closure
4221 G1STWDrainQueueClosure drain_queue(this, pss);
4222
4223 // Setup the soft refs policy...
4224 rp->setup_policy(false);
4225
4226 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4227
4228 ReferenceProcessorStats stats;
4229 if (!rp->processing_is_mt()) {
4230 // Serial reference processing...
4231 stats = rp->process_discovered_references(&is_alive,
4232 &keep_alive,
4233 &drain_queue,
4234 NULL,
4235 pt);
4236 } else {
4237 uint no_of_gc_workers = workers()->active_workers();
4238
4239 // Parallel reference processing
4240 assert(no_of_gc_workers <= rp->max_num_q(),
4241 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4242 no_of_gc_workers, rp->max_num_q());
4243
4244 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4245 stats = rp->process_discovered_references(&is_alive,
4246 &keep_alive,
4247 &drain_queue,
4248 &par_task_executor,
4249 pt);
4250 }
4251
4252 _gc_tracer_stw->report_gc_reference_stats(stats);
4253
4254 // We have completed copying any necessary live referent objects.
4255 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4256
4257 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4258 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4259 }
4260
4261 // Weak Reference processing during an evacuation pause (part 2).
4262 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4263 double ref_enq_start = os::elapsedTime();
4264
4265 ReferenceProcessor* rp = _ref_processor_stw;
4266 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4267
4268 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4269
4270 // Now enqueue any remaining on the discovered lists on to
4271 // the pending list.
4272 if (!rp->processing_is_mt()) {
4273 // Serial reference processing...
4274 rp->enqueue_discovered_references(NULL, pt);
4275 } else {
4276 // Parallel reference enqueueing
4277
4278 uint n_workers = workers()->active_workers();
4279
4280 assert(n_workers <= rp->max_num_q(),
4281 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4282 n_workers, rp->max_num_q());
4283
4284 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4285 rp->enqueue_discovered_references(&par_task_executor, pt);
4286 }
4287
4288 rp->verify_no_references_recorded();
4289 assert(!rp->discovery_enabled(), "should have been disabled");
4290
4291 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4292 // ensure that it is marked in the bitmap for concurrent marking to discover.
4293 if (collector_state()->during_initial_mark_pause()) {
4294 oop pll_head = Universe::reference_pending_list();
4295 if (pll_head != NULL) {
4296 _cm->mark_in_next_bitmap(pll_head);
4297 }
4298 }
4299
4300 // FIXME
4301 // CM's reference processing also cleans up the string and symbol tables.
4302 // Should we do that here also? We could, but it is a serial operation
4303 // and could significantly increase the pause time.
4304
4305 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4306 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4307 }
4308
4309 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4310 double merge_pss_time_start = os::elapsedTime();
4311 per_thread_states->flush();
4312 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4313 }
4314
4315 void G1CollectedHeap::pre_evacuate_collection_set() {
4316 _expand_heap_after_alloc_failure = true;
4317 _evacuation_failed = false;
4318
4319 // Disable the hot card cache.
4320 _hot_card_cache->reset_hot_cache_claimed_index();
4321 _hot_card_cache->set_use_cache(false);
4322
4323 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4324 _preserved_marks_set.assert_empty();
4325
4326 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4327
4328 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4329 if (collector_state()->during_initial_mark_pause()) {
4330 double start_clear_claimed_marks = os::elapsedTime();
4331
4332 ClassLoaderDataGraph::clear_claimed_marks();
4333
4334 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4335 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4336 }
4337 }
4338
4339 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4340 // Should G1EvacuationFailureALot be in effect for this GC?
4341 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4342
4343 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4344
4345 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4346
4347 double start_par_time_sec = os::elapsedTime();
4348 double end_par_time_sec;
4349
4350 {
4351 const uint n_workers = workers()->active_workers();
4352 G1RootProcessor root_processor(this, n_workers);
4353 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4354
4355 print_termination_stats_hdr();
4356
4357 workers()->run_task(&g1_par_task);
4358 end_par_time_sec = os::elapsedTime();
4359
4360 // Closing the inner scope will execute the destructor
4361 // for the G1RootProcessor object. We record the current
4362 // elapsed time before closing the scope so that time
4363 // taken for the destructor is NOT included in the
4364 // reported parallel time.
4365 }
4366
4367 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4368 phase_times->record_par_time(par_time_ms);
4369
4370 double code_root_fixup_time_ms =
4371 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4372 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4373 }
4374
4375 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4376 // Process any discovered reference objects - we have
4377 // to do this _before_ we retire the GC alloc regions
4378 // as we may have to copy some 'reachable' referent
4379 // objects (and their reachable sub-graphs) that were
4380 // not copied during the pause.
4381 if (g1_policy()->should_process_references()) {
4382 preserve_cm_referents(per_thread_states);
4383 process_discovered_references(per_thread_states);
4384 } else {
4385 ref_processor_stw()->verify_no_references_recorded();
4386 }
4387
4388 G1STWIsAliveClosure is_alive(this);
4389 G1KeepAliveClosure keep_alive(this);
4390
4391 {
4392 double start = os::elapsedTime();
4393
4394 WeakProcessor::weak_oops_do(&is_alive, &keep_alive);
4395
4396 double time_ms = (os::elapsedTime() - start) * 1000.0;
4397 g1_policy()->phase_times()->record_ref_proc_time(time_ms);
4398 }
4399
4400 if (G1StringDedup::is_enabled()) {
4401 double fixup_start = os::elapsedTime();
4402
4403 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4404
4405 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4406 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4407 }
4408
4409 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4410
4411 if (evacuation_failed()) {
4412 restore_after_evac_failure();
4413
4414 // Reset the G1EvacuationFailureALot counters and flags
4415 // Note: the values are reset only when an actual
4416 // evacuation failure occurs.
4417 NOT_PRODUCT(reset_evacuation_should_fail();)
4418 }
4419
4420 _preserved_marks_set.assert_empty();
4421
4422 // Enqueue any remaining references remaining on the STW
4423 // reference processor's discovered lists. We need to do
4424 // this after the card table is cleaned (and verified) as
4425 // the act of enqueueing entries on to the pending list
4426 // will log these updates (and dirty their associated
4427 // cards). We need these updates logged to update any
4428 // RSets.
4429 if (g1_policy()->should_process_references()) {
4430 enqueue_discovered_references(per_thread_states);
4431 } else {
4432 g1_policy()->phase_times()->record_ref_enq_time(0);
4433 }
4434
4435 _allocator->release_gc_alloc_regions(evacuation_info);
4436
4437 merge_per_thread_state_info(per_thread_states);
4438
4439 // Reset and re-enable the hot card cache.
4440 // Note the counts for the cards in the regions in the
4441 // collection set are reset when the collection set is freed.
4442 _hot_card_cache->reset_hot_cache();
4443 _hot_card_cache->set_use_cache(true);
4444
4445 purge_code_root_memory();
4446
4447 redirty_logged_cards();
4448 #if COMPILER2_OR_JVMCI
4449 double start = os::elapsedTime();
4450 DerivedPointerTable::update_pointers();
4451 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4452 #endif
4453 g1_policy()->print_age_table();
4454 }
4455
4456 void G1CollectedHeap::record_obj_copy_mem_stats() {
4457 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4458
4459 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4460 create_g1_evac_summary(&_old_evac_stats));
4461 }
4462
4463 void G1CollectedHeap::free_region(HeapRegion* hr,
4464 FreeRegionList* free_list,
4465 bool skip_remset,
4466 bool skip_hot_card_cache,
4467 bool locked) {
4468 assert(!hr->is_free(), "the region should not be free");
4469 assert(!hr->is_empty(), "the region should not be empty");
4470 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4471 assert(free_list != NULL, "pre-condition");
4472
4473 if (G1VerifyBitmaps) {
4474 MemRegion mr(hr->bottom(), hr->end());
4475 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4476 }
4477
4478 // Clear the card counts for this region.
4479 // Note: we only need to do this if the region is not young
4480 // (since we don't refine cards in young regions).
4481 if (!skip_hot_card_cache && !hr->is_young()) {
4482 _hot_card_cache->reset_card_counts(hr);
4483 }
4484 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4485 free_list->add_ordered(hr);
4486 }
4487
4488 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4489 FreeRegionList* free_list,
4490 bool skip_remset) {
4491 assert(hr->is_humongous(), "this is only for humongous regions");
4492 assert(free_list != NULL, "pre-condition");
4493 hr->clear_humongous();
4494 free_region(hr, free_list, skip_remset);
4495 }
4496
4497 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4498 const uint humongous_regions_removed) {
4499 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4500 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4501 _old_set.bulk_remove(old_regions_removed);
4502 _humongous_set.bulk_remove(humongous_regions_removed);
4503 }
4504
4505 }
4506
4507 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4508 assert(list != NULL, "list can't be null");
4509 if (!list->is_empty()) {
4510 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4511 _hrm.insert_list_into_free_list(list);
4512 }
4513 }
4514
4515 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4516 decrease_used(bytes);
4517 }
4518
4519 class G1ParScrubRemSetTask: public AbstractGangTask {
4520 protected:
4521 G1RemSet* _g1rs;
4522 HeapRegionClaimer _hrclaimer;
4523
4524 public:
4525 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4526 AbstractGangTask("G1 ScrubRS"),
4527 _g1rs(g1_rs),
4528 _hrclaimer(num_workers) {
4529 }
4530
4531 void work(uint worker_id) {
4532 _g1rs->scrub(worker_id, &_hrclaimer);
4533 }
4534 };
4535
4536 void G1CollectedHeap::scrub_rem_set() {
4537 uint num_workers = workers()->active_workers();
4538 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4539 workers()->run_task(&g1_par_scrub_rs_task);
4540 }
4541
4542 class G1FreeCollectionSetTask : public AbstractGangTask {
4543 private:
4544
4545 // Closure applied to all regions in the collection set to do work that needs to
4546 // be done serially in a single thread.
4547 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4548 private:
4549 EvacuationInfo* _evacuation_info;
4550 const size_t* _surviving_young_words;
4551
4552 // Bytes used in successfully evacuated regions before the evacuation.
4553 size_t _before_used_bytes;
4554 // Bytes used in unsucessfully evacuated regions before the evacuation
4555 size_t _after_used_bytes;
4556
4557 size_t _bytes_allocated_in_old_since_last_gc;
4558
4559 size_t _failure_used_words;
4560 size_t _failure_waste_words;
4561
4562 FreeRegionList _local_free_list;
4563 public:
4564 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4565 HeapRegionClosure(),
4566 _evacuation_info(evacuation_info),
4567 _surviving_young_words(surviving_young_words),
4568 _before_used_bytes(0),
4569 _after_used_bytes(0),
4570 _bytes_allocated_in_old_since_last_gc(0),
4571 _failure_used_words(0),
4572 _failure_waste_words(0),
4573 _local_free_list("Local Region List for CSet Freeing") {
4574 }
4575
4576 virtual bool doHeapRegion(HeapRegion* r) {
4577 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4578
4579 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4580 g1h->clear_in_cset(r);
4581
4582 if (r->is_young()) {
4583 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4584 "Young index %d is wrong for region %u of type %s with %u young regions",
4585 r->young_index_in_cset(),
4586 r->hrm_index(),
4587 r->get_type_str(),
4588 g1h->collection_set()->young_region_length());
4589 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4590 r->record_surv_words_in_group(words_survived);
4591 }
4592
4593 if (!r->evacuation_failed()) {
4594 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4595 _before_used_bytes += r->used();
4596 g1h->free_region(r,
4597 &_local_free_list,
4598 true, /* skip_remset */
4599 true, /* skip_hot_card_cache */
4600 true /* locked */);
4601 } else {
4602 r->uninstall_surv_rate_group();
4603 r->set_young_index_in_cset(-1);
4604 r->set_evacuation_failed(false);
4605 // When moving a young gen region to old gen, we "allocate" that whole region
4606 // there. This is in addition to any already evacuated objects. Notify the
4607 // policy about that.
4608 // Old gen regions do not cause an additional allocation: both the objects
4609 // still in the region and the ones already moved are accounted for elsewhere.
4610 if (r->is_young()) {
4611 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4612 }
4613 // The region is now considered to be old.
4614 r->set_old();
4615 // Do some allocation statistics accounting. Regions that failed evacuation
4616 // are always made old, so there is no need to update anything in the young
4617 // gen statistics, but we need to update old gen statistics.
4618 size_t used_words = r->marked_bytes() / HeapWordSize;
4619
4620 _failure_used_words += used_words;
4621 _failure_waste_words += HeapRegion::GrainWords - used_words;
4622
4623 g1h->old_set_add(r);
4624 _after_used_bytes += r->used();
4625 }
4626 return false;
4627 }
4628
4629 void complete_work() {
4630 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4631
4632 _evacuation_info->set_regions_freed(_local_free_list.length());
4633 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4634
4635 g1h->prepend_to_freelist(&_local_free_list);
4636 g1h->decrement_summary_bytes(_before_used_bytes);
4637
4638 G1Policy* policy = g1h->g1_policy();
4639 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4640
4641 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4642 }
4643 };
4644
4645 G1CollectionSet* _collection_set;
4646 G1SerialFreeCollectionSetClosure _cl;
4647 const size_t* _surviving_young_words;
4648
4649 size_t _rs_lengths;
4650
4651 volatile jint _serial_work_claim;
4652
4653 struct WorkItem {
4654 uint region_idx;
4655 bool is_young;
4656 bool evacuation_failed;
4657
4658 WorkItem(HeapRegion* r) {
4659 region_idx = r->hrm_index();
4660 is_young = r->is_young();
4661 evacuation_failed = r->evacuation_failed();
4662 }
4663 };
4664
4665 volatile size_t _parallel_work_claim;
4666 size_t _num_work_items;
4667 WorkItem* _work_items;
4668
4669 void do_serial_work() {
4670 // Need to grab the lock to be allowed to modify the old region list.
4671 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4672 _collection_set->iterate(&_cl);
4673 }
4674
4675 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4676 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4677
4678 HeapRegion* r = g1h->region_at(region_idx);
4679 assert(!g1h->is_on_master_free_list(r), "sanity");
4680
4681 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4682
4683 if (!is_young) {
4684 g1h->_hot_card_cache->reset_card_counts(r);
4685 }
4686
4687 if (!evacuation_failed) {
4688 r->rem_set()->clear_locked();
4689 }
4690 }
4691
4692 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4693 private:
4694 size_t _cur_idx;
4695 WorkItem* _work_items;
4696 public:
4697 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4698
4699 virtual bool doHeapRegion(HeapRegion* r) {
4700 _work_items[_cur_idx++] = WorkItem(r);
4701 return false;
4702 }
4703 };
4704
4705 void prepare_work() {
4706 G1PrepareFreeCollectionSetClosure cl(_work_items);
4707 _collection_set->iterate(&cl);
4708 }
4709
4710 void complete_work() {
4711 _cl.complete_work();
4712
4713 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4714 policy->record_max_rs_lengths(_rs_lengths);
4715 policy->cset_regions_freed();
4716 }
4717 public:
4718 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4719 AbstractGangTask("G1 Free Collection Set"),
4720 _cl(evacuation_info, surviving_young_words),
4721 _collection_set(collection_set),
4722 _surviving_young_words(surviving_young_words),
4723 _serial_work_claim(0),
4724 _rs_lengths(0),
4725 _parallel_work_claim(0),
4726 _num_work_items(collection_set->region_length()),
4727 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4728 prepare_work();
4729 }
4730
4731 ~G1FreeCollectionSetTask() {
4732 complete_work();
4733 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4734 }
4735
4736 // Chunk size for work distribution. The chosen value has been determined experimentally
4737 // to be a good tradeoff between overhead and achievable parallelism.
4738 static uint chunk_size() { return 32; }
4739
4740 virtual void work(uint worker_id) {
4741 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4742
4743 // Claim serial work.
4744 if (_serial_work_claim == 0) {
4745 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4746 if (value == 0) {
4747 double serial_time = os::elapsedTime();
4748 do_serial_work();
4749 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4750 }
4751 }
4752
4753 // Start parallel work.
4754 double young_time = 0.0;
4755 bool has_young_time = false;
4756 double non_young_time = 0.0;
4757 bool has_non_young_time = false;
4758
4759 while (true) {
4760 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4761 size_t cur = end - chunk_size();
4762
4763 if (cur >= _num_work_items) {
4764 break;
4765 }
4766
4767 double start_time = os::elapsedTime();
4768
4769 end = MIN2(end, _num_work_items);
4770
4771 for (; cur < end; cur++) {
4772 bool is_young = _work_items[cur].is_young;
4773
4774 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4775
4776 double end_time = os::elapsedTime();
4777 double time_taken = end_time - start_time;
4778 if (is_young) {
4779 young_time += time_taken;
4780 has_young_time = true;
4781 } else {
4782 non_young_time += time_taken;
4783 has_non_young_time = true;
4784 }
4785 start_time = end_time;
4786 }
4787 }
4788
4789 if (has_young_time) {
4790 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4791 }
4792 if (has_non_young_time) {
4793 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4794 }
4795 }
4796 };
4797
4798 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4799 _eden.clear();
4800
4801 double free_cset_start_time = os::elapsedTime();
4802
4803 {
4804 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4805 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4806
4807 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4808
4809 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4810 cl.name(),
4811 num_workers,
4812 _collection_set.region_length());
4813 workers()->run_task(&cl, num_workers);
4814 }
4815 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4816
4817 collection_set->clear();
4818 }
4819
4820 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4821 private:
4822 FreeRegionList* _free_region_list;
4823 HeapRegionSet* _proxy_set;
4824 uint _humongous_objects_reclaimed;
4825 uint _humongous_regions_reclaimed;
4826 size_t _freed_bytes;
4827 public:
4828
4829 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4830 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4831 }
4832
4833 virtual bool doHeapRegion(HeapRegion* r) {
4834 if (!r->is_starts_humongous()) {
4835 return false;
4836 }
4837
4838 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4839
4840 oop obj = (oop)r->bottom();
4841 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4842
4843 // The following checks whether the humongous object is live are sufficient.
4844 // The main additional check (in addition to having a reference from the roots
4845 // or the young gen) is whether the humongous object has a remembered set entry.
4846 //
4847 // A humongous object cannot be live if there is no remembered set for it
4848 // because:
4849 // - there can be no references from within humongous starts regions referencing
4850 // the object because we never allocate other objects into them.
4851 // (I.e. there are no intra-region references that may be missed by the
4852 // remembered set)
4853 // - as soon there is a remembered set entry to the humongous starts region
4854 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4855 // until the end of a concurrent mark.
4856 //
4857 // It is not required to check whether the object has been found dead by marking
4858 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4859 // all objects allocated during that time are considered live.
4860 // SATB marking is even more conservative than the remembered set.
4861 // So if at this point in the collection there is no remembered set entry,
4862 // nobody has a reference to it.
4863 // At the start of collection we flush all refinement logs, and remembered sets
4864 // are completely up-to-date wrt to references to the humongous object.
4865 //
4866 // Other implementation considerations:
4867 // - never consider object arrays at this time because they would pose
4868 // considerable effort for cleaning up the the remembered sets. This is
4869 // required because stale remembered sets might reference locations that
4870 // are currently allocated into.
4871 uint region_idx = r->hrm_index();
4872 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4873 !r->rem_set()->is_empty()) {
4874 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",
4875 region_idx,
4876 (size_t)obj->size() * HeapWordSize,
4877 p2i(r->bottom()),
4878 r->rem_set()->occupied(),
4879 r->rem_set()->strong_code_roots_list_length(),
4880 next_bitmap->is_marked(r->bottom()),
4881 g1h->is_humongous_reclaim_candidate(region_idx),
4882 obj->is_typeArray()
4883 );
4884 return false;
4885 }
4886
4887 guarantee(obj->is_typeArray(),
4888 "Only eagerly reclaiming type arrays is supported, but the object "
4889 PTR_FORMAT " is not.", p2i(r->bottom()));
4890
4891 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",
4892 region_idx,
4893 (size_t)obj->size() * HeapWordSize,
4894 p2i(r->bottom()),
4895 r->rem_set()->occupied(),
4896 r->rem_set()->strong_code_roots_list_length(),
4897 next_bitmap->is_marked(r->bottom()),
4898 g1h->is_humongous_reclaim_candidate(region_idx),
4899 obj->is_typeArray()
4900 );
4901
4902 // Need to clear mark bit of the humongous object if already set.
4903 if (next_bitmap->is_marked(r->bottom())) {
4904 next_bitmap->clear(r->bottom());
4905 }
4906 _humongous_objects_reclaimed++;
4907 do {
4908 HeapRegion* next = g1h->next_region_in_humongous(r);
4909 _freed_bytes += r->used();
4910 r->set_containing_set(NULL);
4911 _humongous_regions_reclaimed++;
4912 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4913 r = next;
4914 } while (r != NULL);
4915
4916 return false;
4917 }
4918
4919 uint humongous_objects_reclaimed() {
4920 return _humongous_objects_reclaimed;
4921 }
4922
4923 uint humongous_regions_reclaimed() {
4924 return _humongous_regions_reclaimed;
4925 }
4926
4927 size_t bytes_freed() const {
4928 return _freed_bytes;
4929 }
4930 };
4931
4932 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4933 assert_at_safepoint(true);
4934
4935 if (!G1EagerReclaimHumongousObjects ||
4936 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4937 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4938 return;
4939 }
4940
4941 double start_time = os::elapsedTime();
4942
4943 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4944
4945 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4946 heap_region_iterate(&cl);
4947
4948 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4949
4950 G1HRPrinter* hrp = hr_printer();
4951 if (hrp->is_active()) {
4952 FreeRegionListIterator iter(&local_cleanup_list);
4953 while (iter.more_available()) {
4954 HeapRegion* hr = iter.get_next();
4955 hrp->cleanup(hr);
4956 }
4957 }
4958
4959 prepend_to_freelist(&local_cleanup_list);
4960 decrement_summary_bytes(cl.bytes_freed());
4961
4962 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4963 cl.humongous_objects_reclaimed());
4964 }
4965
4966 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4967 public:
4968 virtual bool doHeapRegion(HeapRegion* r) {
4969 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4970 G1CollectedHeap::heap()->clear_in_cset(r);
4971 r->set_young_index_in_cset(-1);
4972 return false;
4973 }
4974 };
4975
4976 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4977 G1AbandonCollectionSetClosure cl;
4978 collection_set->iterate(&cl);
4979
4980 collection_set->clear();
4981 collection_set->stop_incremental_building();
4982 }
4983
4984 void G1CollectedHeap::set_free_regions_coming() {
4985 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4986
4987 assert(!free_regions_coming(), "pre-condition");
4988 _free_regions_coming = true;
4989 }
4990
4991 void G1CollectedHeap::reset_free_regions_coming() {
4992 assert(free_regions_coming(), "pre-condition");
4993
4994 {
4995 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4996 _free_regions_coming = false;
4997 SecondaryFreeList_lock->notify_all();
4998 }
4999
5000 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5001 }
5002
5003 void G1CollectedHeap::wait_while_free_regions_coming() {
5004 // Most of the time we won't have to wait, so let's do a quick test
5005 // first before we take the lock.
5006 if (!free_regions_coming()) {
5007 return;
5008 }
5009
5010 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5011
5012 {
5013 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5014 while (free_regions_coming()) {
5015 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5016 }
5017 }
5018
5019 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5020 }
5021
5022 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5023 return _allocator->is_retained_old_region(hr);
5024 }
5025
5026 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5027 _eden.add(hr);
5028 _g1_policy->set_region_eden(hr);
5029 }
5030
5031 #ifdef ASSERT
5032
5033 class NoYoungRegionsClosure: public HeapRegionClosure {
5034 private:
5035 bool _success;
5036 public:
5037 NoYoungRegionsClosure() : _success(true) { }
5038 bool doHeapRegion(HeapRegion* r) {
5039 if (r->is_young()) {
5040 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5041 p2i(r->bottom()), p2i(r->end()));
5042 _success = false;
5043 }
5044 return false;
5045 }
5046 bool success() { return _success; }
5047 };
5048
5049 bool G1CollectedHeap::check_young_list_empty() {
5050 bool ret = (young_regions_count() == 0);
5051
5052 NoYoungRegionsClosure closure;
5053 heap_region_iterate(&closure);
5054 ret = ret && closure.success();
5055
5056 return ret;
5057 }
5058
5059 #endif // ASSERT
5060
5061 class TearDownRegionSetsClosure : public HeapRegionClosure {
5062 private:
5063 HeapRegionSet *_old_set;
5064
5065 public:
5066 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5067
5068 bool doHeapRegion(HeapRegion* r) {
5069 if (r->is_old()) {
5070 _old_set->remove(r);
5071 } else if(r->is_young()) {
5072 r->uninstall_surv_rate_group();
5073 } else {
5074 // We ignore free regions, we'll empty the free list afterwards.
5075 // We ignore humongous regions, we're not tearing down the
5076 // humongous regions set.
5077 assert(r->is_free() || r->is_humongous(),
5078 "it cannot be another type");
5079 }
5080 return false;
5081 }
5082
5083 ~TearDownRegionSetsClosure() {
5084 assert(_old_set->is_empty(), "post-condition");
5085 }
5086 };
5087
5088 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5089 assert_at_safepoint(true /* should_be_vm_thread */);
5090
5091 if (!free_list_only) {
5092 TearDownRegionSetsClosure cl(&_old_set);
5093 heap_region_iterate(&cl);
5094
5095 // Note that emptying the _young_list is postponed and instead done as
5096 // the first step when rebuilding the regions sets again. The reason for
5097 // this is that during a full GC string deduplication needs to know if
5098 // a collected region was young or old when the full GC was initiated.
5099 }
5100 _hrm.remove_all_free_regions();
5101 }
5102
5103 void G1CollectedHeap::increase_used(size_t bytes) {
5104 _summary_bytes_used += bytes;
5105 }
5106
5107 void G1CollectedHeap::decrease_used(size_t bytes) {
5108 assert(_summary_bytes_used >= bytes,
5109 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5110 _summary_bytes_used, bytes);
5111 _summary_bytes_used -= bytes;
5112 }
5113
5114 void G1CollectedHeap::set_used(size_t bytes) {
5115 _summary_bytes_used = bytes;
5116 }
5117
5118 class RebuildRegionSetsClosure : public HeapRegionClosure {
5119 private:
5120 bool _free_list_only;
5121 HeapRegionSet* _old_set;
5122 HeapRegionManager* _hrm;
5123 size_t _total_used;
5124
5125 public:
5126 RebuildRegionSetsClosure(bool free_list_only,
5127 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5128 _free_list_only(free_list_only),
5129 _old_set(old_set), _hrm(hrm), _total_used(0) {
5130 assert(_hrm->num_free_regions() == 0, "pre-condition");
5131 if (!free_list_only) {
5132 assert(_old_set->is_empty(), "pre-condition");
5133 }
5134 }
5135
5136 bool doHeapRegion(HeapRegion* r) {
5137 if (r->is_empty()) {
5138 // Add free regions to the free list
5139 r->set_free();
5140 r->set_allocation_context(AllocationContext::system());
5141 _hrm->insert_into_free_list(r);
5142 } else if (!_free_list_only) {
5143
5144 if (r->is_humongous()) {
5145 // We ignore humongous regions. We left the humongous set unchanged.
5146 } else {
5147 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5148 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5149 r->move_to_old();
5150 _old_set->add(r);
5151 }
5152 _total_used += r->used();
5153 }
5154
5155 return false;
5156 }
5157
5158 size_t total_used() {
5159 return _total_used;
5160 }
5161 };
5162
5163 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5164 assert_at_safepoint(true /* should_be_vm_thread */);
5165
5166 if (!free_list_only) {
5167 _eden.clear();
5168 _survivor.clear();
5169 }
5170
5171 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5172 heap_region_iterate(&cl);
5173
5174 if (!free_list_only) {
5175 set_used(cl.total_used());
5176 if (_archive_allocator != NULL) {
5177 _archive_allocator->clear_used();
5178 }
5179 }
5180 assert(used_unlocked() == recalculate_used(),
5181 "inconsistent used_unlocked(), "
5182 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5183 used_unlocked(), recalculate_used());
5184 }
5185
5186 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5187 HeapRegion* hr = heap_region_containing(p);
5188 return hr->is_in(p);
5189 }
5190
5191 // Methods for the mutator alloc region
5192
5193 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5194 bool force) {
5195 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5196 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5197 if (force || should_allocate) {
5198 HeapRegion* new_alloc_region = new_region(word_size,
5199 false /* is_old */,
5200 false /* do_expand */);
5201 if (new_alloc_region != NULL) {
5202 set_region_short_lived_locked(new_alloc_region);
5203 _hr_printer.alloc(new_alloc_region, !should_allocate);
5204 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5205 return new_alloc_region;
5206 }
5207 }
5208 return NULL;
5209 }
5210
5211 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5212 size_t allocated_bytes) {
5213 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5214 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5215
5216 collection_set()->add_eden_region(alloc_region);
5217 increase_used(allocated_bytes);
5218 _hr_printer.retire(alloc_region);
5219 // We update the eden sizes here, when the region is retired,
5220 // instead of when it's allocated, since this is the point that its
5221 // used space has been recored in _summary_bytes_used.
5222 g1mm()->update_eden_size();
5223 }
5224
5225 // Methods for the GC alloc regions
5226
5227 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5228 if (dest.is_old()) {
5229 return true;
5230 } else {
5231 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5232 }
5233 }
5234
5235 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5236 assert(FreeList_lock->owned_by_self(), "pre-condition");
5237
5238 if (!has_more_regions(dest)) {
5239 return NULL;
5240 }
5241
5242 const bool is_survivor = dest.is_young();
5243
5244 HeapRegion* new_alloc_region = new_region(word_size,
5245 !is_survivor,
5246 true /* do_expand */);
5247 if (new_alloc_region != NULL) {
5248 // We really only need to do this for old regions given that we
5249 // should never scan survivors. But it doesn't hurt to do it
5250 // for survivors too.
5251 new_alloc_region->record_timestamp();
5252 if (is_survivor) {
5253 new_alloc_region->set_survivor();
5254 _survivor.add(new_alloc_region);
5255 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5256 } else {
5257 new_alloc_region->set_old();
5258 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5259 }
5260 _hr_printer.alloc(new_alloc_region);
5261 bool during_im = collector_state()->during_initial_mark_pause();
5262 new_alloc_region->note_start_of_copying(during_im);
5263 return new_alloc_region;
5264 }
5265 return NULL;
5266 }
5267
5268 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5269 size_t allocated_bytes,
5270 InCSetState dest) {
5271 bool during_im = collector_state()->during_initial_mark_pause();
5272 alloc_region->note_end_of_copying(during_im);
5273 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5274 if (dest.is_old()) {
5275 _old_set.add(alloc_region);
5276 }
5277 _hr_printer.retire(alloc_region);
5278 }
5279
5280 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5281 bool expanded = false;
5282 uint index = _hrm.find_highest_free(&expanded);
5283
5284 if (index != G1_NO_HRM_INDEX) {
5285 if (expanded) {
5286 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5287 HeapRegion::GrainWords * HeapWordSize);
5288 }
5289 _hrm.allocate_free_regions_starting_at(index, 1);
5290 return region_at(index);
5291 }
5292 return NULL;
5293 }
5294
5295 // Optimized nmethod scanning
5296
5297 class RegisterNMethodOopClosure: public OopClosure {
5298 G1CollectedHeap* _g1h;
5299 nmethod* _nm;
5300
5301 template <class T> void do_oop_work(T* p) {
5302 T heap_oop = oopDesc::load_heap_oop(p);
5303 if (!oopDesc::is_null(heap_oop)) {
5304 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5305 HeapRegion* hr = _g1h->heap_region_containing(obj);
5306 assert(!hr->is_continues_humongous(),
5307 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5308 " starting at " HR_FORMAT,
5309 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5310
5311 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5312 hr->add_strong_code_root_locked(_nm);
5313 }
5314 }
5315
5316 public:
5317 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5318 _g1h(g1h), _nm(nm) {}
5319
5320 void do_oop(oop* p) { do_oop_work(p); }
5321 void do_oop(narrowOop* p) { do_oop_work(p); }
5322 };
5323
5324 class UnregisterNMethodOopClosure: public OopClosure {
5325 G1CollectedHeap* _g1h;
5326 nmethod* _nm;
5327
5328 template <class T> void do_oop_work(T* p) {
5329 T heap_oop = oopDesc::load_heap_oop(p);
5330 if (!oopDesc::is_null(heap_oop)) {
5331 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5332 HeapRegion* hr = _g1h->heap_region_containing(obj);
5333 assert(!hr->is_continues_humongous(),
5334 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5335 " starting at " HR_FORMAT,
5336 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5337
5338 hr->remove_strong_code_root(_nm);
5339 }
5340 }
5341
5342 public:
5343 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5344 _g1h(g1h), _nm(nm) {}
5345
5346 void do_oop(oop* p) { do_oop_work(p); }
5347 void do_oop(narrowOop* p) { do_oop_work(p); }
5348 };
5349
5350 // Returns true if the reference points to an object that
5351 // can move in an incremental collection.
5352 bool G1CollectedHeap::is_scavengable(oop obj) {
5353 HeapRegion* hr = heap_region_containing(obj);
5354 return !hr->is_pinned();
5355 }
5356
5357 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5358 guarantee(nm != NULL, "sanity");
5359 RegisterNMethodOopClosure reg_cl(this, nm);
5360 nm->oops_do(®_cl);
5361 }
5362
5363 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5364 guarantee(nm != NULL, "sanity");
5365 UnregisterNMethodOopClosure reg_cl(this, nm);
5366 nm->oops_do(®_cl, true);
5367 }
5368
5369 void G1CollectedHeap::purge_code_root_memory() {
5370 double purge_start = os::elapsedTime();
5371 G1CodeRootSet::purge();
5372 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5373 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5374 }
5375
5376 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5377 G1CollectedHeap* _g1h;
5378
5379 public:
5380 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5381 _g1h(g1h) {}
5382
5383 void do_code_blob(CodeBlob* cb) {
5384 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5385 if (nm == NULL) {
5386 return;
5387 }
5388
5389 if (ScavengeRootsInCode) {
5390 _g1h->register_nmethod(nm);
5391 }
5392 }
5393 };
5394
5395 void G1CollectedHeap::rebuild_strong_code_roots() {
5396 RebuildStrongCodeRootClosure blob_cl(this);
5397 CodeCache::blobs_do(&blob_cl);
5398 }
5399
5400 class G1YoungGenMemoryManager : public GCMemoryManager {
5401 private:
5402 public:
5403 G1YoungGenMemoryManager() : GCMemoryManager() {}
5404
5405 const char* name() { return "G1 Young Generation"; }
5406 };
5407
5408 class G1OldGenMemoryManager : public GCMemoryManager {
5409 private:
5410 public:
5411 G1OldGenMemoryManager() : GCMemoryManager() {}
5412
5413 const char* name() { return "G1 Old Generation"; }
5414 };
5415
5416 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
5417 _minor_mgr = new G1YoungGenMemoryManager();
5418 _major_mgr = new G1OldGenMemoryManager();
5419 GrowableArray<GCMemoryManager*> mem_mgrs;
5420 mem_mgrs.append(_minor_mgr);
5421 mem_mgrs.append(_major_mgr);
5422 return mem_mgrs;
5423 }
5424
5425 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
5426 G1EdenPool* eden = new G1EdenPool(this);
5427 G1SurvivorPool* survivor = new G1SurvivorPool(this);
5428 G1OldGenPool* old_gen = new G1OldGenPool(this);
5429
5430 _major_mgr->add_pool(eden);
5431 _major_mgr->add_pool(survivor);
5432 _major_mgr->add_pool(old_gen);
5433 _minor_mgr->add_pool(eden);
5434 _minor_mgr->add_pool(survivor);
5435
5436 GrowableArray<MemoryPool*> mem_pools;
5437 mem_pools.append(eden);
5438 mem_pools.append(survivor);
5439 mem_pools.append(old_gen);
5440 return mem_pools;
5441 }