1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MarkSweep.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/heapRegion.inline.hpp"
57 #include "gc/g1/heapRegionRemSet.hpp"
58 #include "gc/g1/heapRegionSet.inline.hpp"
59 #include "gc/g1/suspendibleThreadSet.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/gcHeapSummary.hpp"
62 #include "gc/shared/gcId.hpp"
63 #include "gc/shared/gcLocker.inline.hpp"
64 #include "gc/shared/gcTimer.hpp"
65 #include "gc/shared/gcTrace.hpp"
66 #include "gc/shared/gcTraceTime.inline.hpp"
67 #include "gc/shared/generationSpec.hpp"
68 #include "gc/shared/isGCActiveMark.hpp"
69 #include "gc/shared/preservedMarks.inline.hpp"
70 #include "gc/shared/referenceProcessor.inline.hpp"
71 #include "gc/shared/taskqueue.inline.hpp"
72 #include "logging/log.hpp"
73 #include "memory/allocation.hpp"
74 #include "memory/iterator.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "oops/oop.inline.hpp"
77 #include "runtime/atomic.inline.hpp"
78 #include "runtime/init.hpp"
79 #include "runtime/orderAccess.inline.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "utilities/globalDefinitions.hpp"
82 #include "utilities/stack.inline.hpp"
83
84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
85
86 // INVARIANTS/NOTES
87 //
88 // All allocation activity covered by the G1CollectedHeap interface is
89 // serialized by acquiring the HeapLock. This happens in mem_allocate
90 // and allocate_new_tlab, which are the "entry" points to the
91 // allocation code from the rest of the JVM. (Note that this does not
92 // apply to TLAB allocation, which is not part of this interface: it
93 // is done by clients of this interface.)
94
95 // Local to this file.
96
97 class RefineCardTableEntryClosure: public CardTableEntryClosure {
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure() : _concurrent(true) { }
101
102 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
103 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL);
104 // This path is executed by the concurrent refine or mutator threads,
105 // concurrently, and so we do not care if card_ptr contains references
106 // that point into the collection set.
107 assert(!oops_into_cset, "should be");
108
109 if (_concurrent && SuspendibleThreadSet::should_yield()) {
110 // Caller will actually yield.
111 return false;
112 }
113 // Otherwise, we finished successfully; return true.
114 return true;
115 }
116
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
122 private:
123 size_t _num_dirtied;
124 G1CollectedHeap* _g1h;
125 G1SATBCardTableLoggingModRefBS* _g1_bs;
126
127 HeapRegion* region_for_card(jbyte* card_ptr) const {
128 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
129 }
130
131 bool will_become_free(HeapRegion* hr) const {
132 // A region will be freed by free_collection_set if the region is in the
133 // collection set and has not had an evacuation failure.
134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
135 }
136
137 public:
138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
139 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
140
141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
142 HeapRegion* hr = region_for_card(card_ptr);
143
144 // Should only dirty cards in regions that won't be freed.
145 if (!will_become_free(hr)) {
146 *card_ptr = CardTableModRefBS::dirty_card_val();
147 _num_dirtied++;
148 }
149
150 return true;
151 }
152
153 size_t num_dirtied() const { return _num_dirtied; }
154 };
155
156
157 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
158 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
159 }
160
161 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
162 // The from card cache is not the memory that is actually committed. So we cannot
163 // take advantage of the zero_filled parameter.
164 reset_from_card_cache(start_idx, num_regions);
165 }
166
167 // Returns true if the reference points to an object that
168 // can move in an incremental collection.
169 bool G1CollectedHeap::is_scavengable(const void* p) {
170 HeapRegion* hr = heap_region_containing(p);
171 return !hr->is_pinned();
172 }
173
174 // Private methods.
175
176 HeapRegion*
177 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
179 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
180 if (!_secondary_free_list.is_empty()) {
181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
182 "secondary_free_list has %u entries",
183 _secondary_free_list.length());
184 // It looks as if there are free regions available on the
185 // secondary_free_list. Let's move them to the free_list and try
186 // again to allocate from it.
187 append_secondary_free_list();
188
189 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
190 "empty we should have moved at least one entry to the free_list");
191 HeapRegion* res = _hrm.allocate_free_region(is_old);
192 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
193 "allocated " HR_FORMAT " from secondary_free_list",
194 HR_FORMAT_PARAMS(res));
195 return res;
196 }
197
198 // Wait here until we get notified either when (a) there are no
199 // more free regions coming or (b) some regions have been moved on
200 // the secondary_free_list.
201 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
202 }
203
204 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
205 "could not allocate from secondary_free_list");
206 return NULL;
207 }
208
209 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
210 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
211 "the only time we use this to allocate a humongous region is "
212 "when we are allocating a single humongous region");
213
214 HeapRegion* res;
215 if (G1StressConcRegionFreeing) {
216 if (!_secondary_free_list.is_empty()) {
217 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
218 "forced to look at the secondary_free_list");
219 res = new_region_try_secondary_free_list(is_old);
220 if (res != NULL) {
221 return res;
222 }
223 }
224 }
225
226 res = _hrm.allocate_free_region(is_old);
227
228 if (res == NULL) {
229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
230 "res == NULL, trying the secondary_free_list");
231 res = new_region_try_secondary_free_list(is_old);
232 }
233 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
234 // Currently, only attempts to allocate GC alloc regions set
235 // do_expand to true. So, we should only reach here during a
236 // safepoint. If this assumption changes we might have to
237 // reconsider the use of _expand_heap_after_alloc_failure.
238 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
239
240 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
241 word_size * HeapWordSize);
242
243 if (expand(word_size * HeapWordSize)) {
244 // Given that expand() succeeded in expanding the heap, and we
245 // always expand the heap by an amount aligned to the heap
246 // region size, the free list should in theory not be empty.
247 // In either case allocate_free_region() will check for NULL.
248 res = _hrm.allocate_free_region(is_old);
249 } else {
250 _expand_heap_after_alloc_failure = false;
251 }
252 }
253 return res;
254 }
255
256 HeapWord*
257 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
258 uint num_regions,
259 size_t word_size,
260 AllocationContext_t context) {
261 assert(first != G1_NO_HRM_INDEX, "pre-condition");
262 assert(is_humongous(word_size), "word_size should be humongous");
263 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
264
265 // Index of last region in the series.
266 uint last = first + num_regions - 1;
267
268 // We need to initialize the region(s) we just discovered. This is
269 // a bit tricky given that it can happen concurrently with
270 // refinement threads refining cards on these regions and
271 // potentially wanting to refine the BOT as they are scanning
272 // those cards (this can happen shortly after a cleanup; see CR
273 // 6991377). So we have to set up the region(s) carefully and in
274 // a specific order.
275
276 // The word size sum of all the regions we will allocate.
277 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
278 assert(word_size <= word_size_sum, "sanity");
279
280 // This will be the "starts humongous" region.
281 HeapRegion* first_hr = region_at(first);
282 // The header of the new object will be placed at the bottom of
283 // the first region.
284 HeapWord* new_obj = first_hr->bottom();
285 // This will be the new top of the new object.
286 HeapWord* obj_top = new_obj + word_size;
287
288 // First, we need to zero the header of the space that we will be
289 // allocating. When we update top further down, some refinement
290 // threads might try to scan the region. By zeroing the header we
291 // ensure that any thread that will try to scan the region will
292 // come across the zero klass word and bail out.
293 //
294 // NOTE: It would not have been correct to have used
295 // CollectedHeap::fill_with_object() and make the space look like
296 // an int array. The thread that is doing the allocation will
297 // later update the object header to a potentially different array
298 // type and, for a very short period of time, the klass and length
299 // fields will be inconsistent. This could cause a refinement
300 // thread to calculate the object size incorrectly.
301 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
302
303 // How many words we use for filler objects.
304 size_t word_fill_size = word_size_sum - word_size;
305
306 // How many words memory we "waste" which cannot hold a filler object.
307 size_t words_not_fillable = 0;
308
309 if (word_fill_size >= min_fill_size()) {
310 fill_with_objects(obj_top, word_fill_size);
311 } else if (word_fill_size > 0) {
312 // We have space to fill, but we cannot fit an object there.
313 words_not_fillable = word_fill_size;
314 word_fill_size = 0;
315 }
316
317 // We will set up the first region as "starts humongous". This
318 // will also update the BOT covering all the regions to reflect
319 // that there is a single object that starts at the bottom of the
320 // first region.
321 first_hr->set_starts_humongous(obj_top, word_fill_size);
322 first_hr->set_allocation_context(context);
323 // Then, if there are any, we will set up the "continues
324 // humongous" regions.
325 HeapRegion* hr = NULL;
326 for (uint i = first + 1; i <= last; ++i) {
327 hr = region_at(i);
328 hr->set_continues_humongous(first_hr);
329 hr->set_allocation_context(context);
330 }
331
332 // Up to this point no concurrent thread would have been able to
333 // do any scanning on any region in this series. All the top
334 // fields still point to bottom, so the intersection between
335 // [bottom,top] and [card_start,card_end] will be empty. Before we
336 // update the top fields, we'll do a storestore to make sure that
337 // no thread sees the update to top before the zeroing of the
338 // object header and the BOT initialization.
339 OrderAccess::storestore();
340
341 // Now, we will update the top fields of the "continues humongous"
342 // regions except the last one.
343 for (uint i = first; i < last; ++i) {
344 hr = region_at(i);
345 hr->set_top(hr->end());
346 }
347
348 hr = region_at(last);
349 // If we cannot fit a filler object, we must set top to the end
350 // of the humongous object, otherwise we cannot iterate the heap
351 // and the BOT will not be complete.
352 hr->set_top(hr->end() - words_not_fillable);
353
354 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
355 "obj_top should be in last region");
356
357 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
358
359 assert(words_not_fillable == 0 ||
360 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
361 "Miscalculation in humongous allocation");
362
363 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
364
365 for (uint i = first; i <= last; ++i) {
366 hr = region_at(i);
367 _humongous_set.add(hr);
368 _hr_printer.alloc(hr);
369 }
370
371 return new_obj;
372 }
373
374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
375 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
376 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
377 }
378
379 // If could fit into free regions w/o expansion, try.
380 // Otherwise, if can expand, do so.
381 // Otherwise, if using ex regions might help, try with ex given back.
382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
383 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
384
385 _verifier->verify_region_sets_optional();
386
387 uint first = G1_NO_HRM_INDEX;
388 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
389
390 if (obj_regions == 1) {
391 // Only one region to allocate, try to use a fast path by directly allocating
392 // from the free lists. Do not try to expand here, we will potentially do that
393 // later.
394 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
395 if (hr != NULL) {
396 first = hr->hrm_index();
397 }
398 } else {
399 // We can't allocate humongous regions spanning more than one region while
400 // cleanupComplete() is running, since some of the regions we find to be
401 // empty might not yet be added to the free list. It is not straightforward
402 // to know in which list they are on so that we can remove them. We only
403 // need to do this if we need to allocate more than one region to satisfy the
404 // current humongous allocation request. If we are only allocating one region
405 // we use the one-region region allocation code (see above), that already
406 // potentially waits for regions from the secondary free list.
407 wait_while_free_regions_coming();
408 append_secondary_free_list_if_not_empty_with_lock();
409
410 // Policy: Try only empty regions (i.e. already committed first). Maybe we
411 // are lucky enough to find some.
412 first = _hrm.find_contiguous_only_empty(obj_regions);
413 if (first != G1_NO_HRM_INDEX) {
414 _hrm.allocate_free_regions_starting_at(first, obj_regions);
415 }
416 }
417
418 if (first == G1_NO_HRM_INDEX) {
419 // Policy: We could not find enough regions for the humongous object in the
420 // free list. Look through the heap to find a mix of free and uncommitted regions.
421 // If so, try expansion.
422 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
423 if (first != G1_NO_HRM_INDEX) {
424 // We found something. Make sure these regions are committed, i.e. expand
425 // the heap. Alternatively we could do a defragmentation GC.
426 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
427 word_size * HeapWordSize);
428
429
430 _hrm.expand_at(first, obj_regions);
431 g1_policy()->record_new_heap_size(num_regions());
432
433 #ifdef ASSERT
434 for (uint i = first; i < first + obj_regions; ++i) {
435 HeapRegion* hr = region_at(i);
436 assert(hr->is_free(), "sanity");
437 assert(hr->is_empty(), "sanity");
438 assert(is_on_master_free_list(hr), "sanity");
439 }
440 #endif
441 _hrm.allocate_free_regions_starting_at(first, obj_regions);
442 } else {
443 // Policy: Potentially trigger a defragmentation GC.
444 }
445 }
446
447 HeapWord* result = NULL;
448 if (first != G1_NO_HRM_INDEX) {
449 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
450 word_size, context);
451 assert(result != NULL, "it should always return a valid result");
452
453 // A successful humongous object allocation changes the used space
454 // information of the old generation so we need to recalculate the
455 // sizes and update the jstat counters here.
456 g1mm()->update_sizes();
457 }
458
459 _verifier->verify_region_sets_optional();
460
461 return result;
462 }
463
464 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
465 assert_heap_not_locked_and_not_at_safepoint();
466 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
467
468 uint dummy_gc_count_before;
469 uint dummy_gclocker_retry_count = 0;
470 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
471 }
472
473 HeapWord*
474 G1CollectedHeap::mem_allocate(size_t word_size,
475 bool* gc_overhead_limit_was_exceeded) {
476 assert_heap_not_locked_and_not_at_safepoint();
477
478 // Loop until the allocation is satisfied, or unsatisfied after GC.
479 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
480 uint gc_count_before;
481
482 HeapWord* result = NULL;
483 if (!is_humongous(word_size)) {
484 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
485 } else {
486 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
487 }
488 if (result != NULL) {
489 return result;
490 }
491
492 // Create the garbage collection operation...
493 VM_G1CollectForAllocation op(gc_count_before, word_size);
494 op.set_allocation_context(AllocationContext::current());
495
496 // ...and get the VM thread to execute it.
497 VMThread::execute(&op);
498
499 if (op.prologue_succeeded() && op.pause_succeeded()) {
500 // If the operation was successful we'll return the result even
501 // if it is NULL. If the allocation attempt failed immediately
502 // after a Full GC, it's unlikely we'll be able to allocate now.
503 HeapWord* result = op.result();
504 if (result != NULL && !is_humongous(word_size)) {
505 // Allocations that take place on VM operations do not do any
506 // card dirtying and we have to do it here. We only have to do
507 // this for non-humongous allocations, though.
508 dirty_young_block(result, word_size);
509 }
510 return result;
511 } else {
512 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
513 return NULL;
514 }
515 assert(op.result() == NULL,
516 "the result should be NULL if the VM op did not succeed");
517 }
518
519 // Give a warning if we seem to be looping forever.
520 if ((QueuedAllocationWarningCount > 0) &&
521 (try_count % QueuedAllocationWarningCount == 0)) {
522 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
523 }
524 }
525
526 ShouldNotReachHere();
527 return NULL;
528 }
529
530 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
531 AllocationContext_t context,
532 uint* gc_count_before_ret,
533 uint* gclocker_retry_count_ret) {
534 // Make sure you read the note in attempt_allocation_humongous().
535
536 assert_heap_not_locked_and_not_at_safepoint();
537 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
538 "be called for humongous allocation requests");
539
540 // We should only get here after the first-level allocation attempt
541 // (attempt_allocation()) failed to allocate.
542
543 // We will loop until a) we manage to successfully perform the
544 // allocation or b) we successfully schedule a collection which
545 // fails to perform the allocation. b) is the only case when we'll
546 // return NULL.
547 HeapWord* result = NULL;
548 for (int try_count = 1; /* we'll return */; try_count += 1) {
549 bool should_try_gc;
550 uint gc_count_before;
551
552 {
553 MutexLockerEx x(Heap_lock);
554 result = _allocator->attempt_allocation_locked(word_size, context);
555 if (result != NULL) {
556 return result;
557 }
558
559 if (GCLocker::is_active_and_needs_gc()) {
560 if (g1_policy()->can_expand_young_list()) {
561 // No need for an ergo verbose message here,
562 // can_expand_young_list() does this when it returns true.
563 result = _allocator->attempt_allocation_force(word_size, context);
564 if (result != NULL) {
565 return result;
566 }
567 }
568 should_try_gc = false;
569 } else {
570 // The GCLocker may not be active but the GCLocker initiated
571 // GC may not yet have been performed (GCLocker::needs_gc()
572 // returns true). In this case we do not try this GC and
573 // wait until the GCLocker initiated GC is performed, and
574 // then retry the allocation.
575 if (GCLocker::needs_gc()) {
576 should_try_gc = false;
577 } else {
578 // Read the GC count while still holding the Heap_lock.
579 gc_count_before = total_collections();
580 should_try_gc = true;
581 }
582 }
583 }
584
585 if (should_try_gc) {
586 bool succeeded;
587 result = do_collection_pause(word_size, gc_count_before, &succeeded,
588 GCCause::_g1_inc_collection_pause);
589 if (result != NULL) {
590 assert(succeeded, "only way to get back a non-NULL result");
591 return result;
592 }
593
594 if (succeeded) {
595 // If we get here we successfully scheduled a collection which
596 // failed to allocate. No point in trying to allocate
597 // further. We'll just return NULL.
598 MutexLockerEx x(Heap_lock);
599 *gc_count_before_ret = total_collections();
600 return NULL;
601 }
602 } else {
603 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
604 MutexLockerEx x(Heap_lock);
605 *gc_count_before_ret = total_collections();
606 return NULL;
607 }
608 // The GCLocker is either active or the GCLocker initiated
609 // GC has not yet been performed. Stall until it is and
610 // then retry the allocation.
611 GCLocker::stall_until_clear();
612 (*gclocker_retry_count_ret) += 1;
613 }
614
615 // We can reach here if we were unsuccessful in scheduling a
616 // collection (because another thread beat us to it) or if we were
617 // stalled due to the GC locker. In either can we should retry the
618 // allocation attempt in case another thread successfully
619 // performed a collection and reclaimed enough space. We do the
620 // first attempt (without holding the Heap_lock) here and the
621 // follow-on attempt will be at the start of the next loop
622 // iteration (after taking the Heap_lock).
623 result = _allocator->attempt_allocation(word_size, context);
624 if (result != NULL) {
625 return result;
626 }
627
628 // Give a warning if we seem to be looping forever.
629 if ((QueuedAllocationWarningCount > 0) &&
630 (try_count % QueuedAllocationWarningCount == 0)) {
631 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
632 "retries %d times", try_count);
633 }
634 }
635
636 ShouldNotReachHere();
637 return NULL;
638 }
639
640 void G1CollectedHeap::begin_archive_alloc_range() {
641 assert_at_safepoint(true /* should_be_vm_thread */);
642 if (_archive_allocator == NULL) {
643 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
644 }
645 }
646
647 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
648 // Allocations in archive regions cannot be of a size that would be considered
649 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
650 // may be different at archive-restore time.
651 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
652 }
653
654 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
655 assert_at_safepoint(true /* should_be_vm_thread */);
656 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
657 if (is_archive_alloc_too_large(word_size)) {
658 return NULL;
659 }
660 return _archive_allocator->archive_mem_allocate(word_size);
661 }
662
663 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
664 size_t end_alignment_in_bytes) {
665 assert_at_safepoint(true /* should_be_vm_thread */);
666 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
667
668 // Call complete_archive to do the real work, filling in the MemRegion
669 // array with the archive regions.
670 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
671 delete _archive_allocator;
672 _archive_allocator = NULL;
673 }
674
675 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
676 assert(ranges != NULL, "MemRegion array NULL");
677 assert(count != 0, "No MemRegions provided");
678 MemRegion reserved = _hrm.reserved();
679 for (size_t i = 0; i < count; i++) {
680 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
681 return false;
682 }
683 }
684 return true;
685 }
686
687 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
688 assert(!is_init_completed(), "Expect to be called at JVM init time");
689 assert(ranges != NULL, "MemRegion array NULL");
690 assert(count != 0, "No MemRegions provided");
691 MutexLockerEx x(Heap_lock);
692
693 MemRegion reserved = _hrm.reserved();
694 HeapWord* prev_last_addr = NULL;
695 HeapRegion* prev_last_region = NULL;
696
697 // Temporarily disable pretouching of heap pages. This interface is used
698 // when mmap'ing archived heap data in, so pre-touching is wasted.
699 FlagSetting fs(AlwaysPreTouch, false);
700
701 // Enable archive object checking in G1MarkSweep. We have to let it know
702 // about each archive range, so that objects in those ranges aren't marked.
703 G1MarkSweep::enable_archive_object_check();
704
705 // For each specified MemRegion range, allocate the corresponding G1
706 // regions and mark them as archive regions. We expect the ranges in
707 // ascending starting address order, without overlap.
708 for (size_t i = 0; i < count; i++) {
709 MemRegion curr_range = ranges[i];
710 HeapWord* start_address = curr_range.start();
711 size_t word_size = curr_range.word_size();
712 HeapWord* last_address = curr_range.last();
713 size_t commits = 0;
714
715 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
716 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
717 p2i(start_address), p2i(last_address));
718 guarantee(start_address > prev_last_addr,
719 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
720 p2i(start_address), p2i(prev_last_addr));
721 prev_last_addr = last_address;
722
723 // Check for ranges that start in the same G1 region in which the previous
724 // range ended, and adjust the start address so we don't try to allocate
725 // the same region again. If the current range is entirely within that
726 // region, skip it, just adjusting the recorded top.
727 HeapRegion* start_region = _hrm.addr_to_region(start_address);
728 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
729 start_address = start_region->end();
730 if (start_address > last_address) {
731 increase_used(word_size * HeapWordSize);
732 start_region->set_top(last_address + 1);
733 continue;
734 }
735 start_region->set_top(start_address);
736 curr_range = MemRegion(start_address, last_address + 1);
737 start_region = _hrm.addr_to_region(start_address);
738 }
739
740 // Perform the actual region allocation, exiting if it fails.
741 // Then note how much new space we have allocated.
742 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
743 return false;
744 }
745 increase_used(word_size * HeapWordSize);
746 if (commits != 0) {
747 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
748 HeapRegion::GrainWords * HeapWordSize * commits);
749
750 }
751
752 // Mark each G1 region touched by the range as archive, add it to the old set,
753 // and set the allocation context and top.
754 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
755 HeapRegion* last_region = _hrm.addr_to_region(last_address);
756 prev_last_region = last_region;
757
758 while (curr_region != NULL) {
759 assert(curr_region->is_empty() && !curr_region->is_pinned(),
760 "Region already in use (index %u)", curr_region->hrm_index());
761 curr_region->set_allocation_context(AllocationContext::system());
762 curr_region->set_archive();
763 _hr_printer.alloc(curr_region);
764 _old_set.add(curr_region);
765 if (curr_region != last_region) {
766 curr_region->set_top(curr_region->end());
767 curr_region = _hrm.next_region_in_heap(curr_region);
768 } else {
769 curr_region->set_top(last_address + 1);
770 curr_region = NULL;
771 }
772 }
773
774 // Notify mark-sweep of the archive range.
775 G1MarkSweep::set_range_archive(curr_range, true);
776 }
777 return true;
778 }
779
780 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
781 assert(!is_init_completed(), "Expect to be called at JVM init time");
782 assert(ranges != NULL, "MemRegion array NULL");
783 assert(count != 0, "No MemRegions provided");
784 MemRegion reserved = _hrm.reserved();
785 HeapWord *prev_last_addr = NULL;
786 HeapRegion* prev_last_region = NULL;
787
788 // For each MemRegion, create filler objects, if needed, in the G1 regions
789 // that contain the address range. The address range actually within the
790 // MemRegion will not be modified. That is assumed to have been initialized
791 // elsewhere, probably via an mmap of archived heap data.
792 MutexLockerEx x(Heap_lock);
793 for (size_t i = 0; i < count; i++) {
794 HeapWord* start_address = ranges[i].start();
795 HeapWord* last_address = ranges[i].last();
796
797 assert(reserved.contains(start_address) && reserved.contains(last_address),
798 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
799 p2i(start_address), p2i(last_address));
800 assert(start_address > prev_last_addr,
801 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
802 p2i(start_address), p2i(prev_last_addr));
803
804 HeapRegion* start_region = _hrm.addr_to_region(start_address);
805 HeapRegion* last_region = _hrm.addr_to_region(last_address);
806 HeapWord* bottom_address = start_region->bottom();
807
808 // Check for a range beginning in the same region in which the
809 // previous one ended.
810 if (start_region == prev_last_region) {
811 bottom_address = prev_last_addr + 1;
812 }
813
814 // Verify that the regions were all marked as archive regions by
815 // alloc_archive_regions.
816 HeapRegion* curr_region = start_region;
817 while (curr_region != NULL) {
818 guarantee(curr_region->is_archive(),
819 "Expected archive region at index %u", curr_region->hrm_index());
820 if (curr_region != last_region) {
821 curr_region = _hrm.next_region_in_heap(curr_region);
822 } else {
823 curr_region = NULL;
824 }
825 }
826
827 prev_last_addr = last_address;
828 prev_last_region = last_region;
829
830 // Fill the memory below the allocated range with dummy object(s),
831 // if the region bottom does not match the range start, or if the previous
832 // range ended within the same G1 region, and there is a gap.
833 if (start_address != bottom_address) {
834 size_t fill_size = pointer_delta(start_address, bottom_address);
835 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
836 increase_used(fill_size * HeapWordSize);
837 }
838 }
839 }
840
841 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
842 uint* gc_count_before_ret,
843 uint* gclocker_retry_count_ret) {
844 assert_heap_not_locked_and_not_at_safepoint();
845 assert(!is_humongous(word_size), "attempt_allocation() should not "
846 "be called for humongous allocation requests");
847
848 AllocationContext_t context = AllocationContext::current();
849 HeapWord* result = _allocator->attempt_allocation(word_size, context);
850
851 if (result == NULL) {
852 result = attempt_allocation_slow(word_size,
853 context,
854 gc_count_before_ret,
855 gclocker_retry_count_ret);
856 }
857 assert_heap_not_locked();
858 if (result != NULL) {
859 dirty_young_block(result, word_size);
860 }
861 return result;
862 }
863
864 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
865 assert(!is_init_completed(), "Expect to be called at JVM init time");
866 assert(ranges != NULL, "MemRegion array NULL");
867 assert(count != 0, "No MemRegions provided");
868 MemRegion reserved = _hrm.reserved();
869 HeapWord* prev_last_addr = NULL;
870 HeapRegion* prev_last_region = NULL;
871 size_t size_used = 0;
872 size_t uncommitted_regions = 0;
873
874 // For each Memregion, free the G1 regions that constitute it, and
875 // notify mark-sweep that the range is no longer to be considered 'archive.'
876 MutexLockerEx x(Heap_lock);
877 for (size_t i = 0; i < count; i++) {
878 HeapWord* start_address = ranges[i].start();
879 HeapWord* last_address = ranges[i].last();
880
881 assert(reserved.contains(start_address) && reserved.contains(last_address),
882 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
883 p2i(start_address), p2i(last_address));
884 assert(start_address > prev_last_addr,
885 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
886 p2i(start_address), p2i(prev_last_addr));
887 size_used += ranges[i].byte_size();
888 prev_last_addr = last_address;
889
890 HeapRegion* start_region = _hrm.addr_to_region(start_address);
891 HeapRegion* last_region = _hrm.addr_to_region(last_address);
892
893 // Check for ranges that start in the same G1 region in which the previous
894 // range ended, and adjust the start address so we don't try to free
895 // the same region again. If the current range is entirely within that
896 // region, skip it.
897 if (start_region == prev_last_region) {
898 start_address = start_region->end();
899 if (start_address > last_address) {
900 continue;
901 }
902 start_region = _hrm.addr_to_region(start_address);
903 }
904 prev_last_region = last_region;
905
906 // After verifying that each region was marked as an archive region by
907 // alloc_archive_regions, set it free and empty and uncommit it.
908 HeapRegion* curr_region = start_region;
909 while (curr_region != NULL) {
910 guarantee(curr_region->is_archive(),
911 "Expected archive region at index %u", curr_region->hrm_index());
912 uint curr_index = curr_region->hrm_index();
913 _old_set.remove(curr_region);
914 curr_region->set_free();
915 curr_region->set_top(curr_region->bottom());
916 if (curr_region != last_region) {
917 curr_region = _hrm.next_region_in_heap(curr_region);
918 } else {
919 curr_region = NULL;
920 }
921 _hrm.shrink_at(curr_index, 1);
922 uncommitted_regions++;
923 }
924
925 // Notify mark-sweep that this is no longer an archive range.
926 G1MarkSweep::set_range_archive(ranges[i], false);
927 }
928
929 if (uncommitted_regions != 0) {
930 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
931 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
932 }
933 decrease_used(size_used);
934 }
935
936 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
937 uint* gc_count_before_ret,
938 uint* gclocker_retry_count_ret) {
939 // The structure of this method has a lot of similarities to
940 // attempt_allocation_slow(). The reason these two were not merged
941 // into a single one is that such a method would require several "if
942 // allocation is not humongous do this, otherwise do that"
943 // conditional paths which would obscure its flow. In fact, an early
944 // version of this code did use a unified method which was harder to
945 // follow and, as a result, it had subtle bugs that were hard to
946 // track down. So keeping these two methods separate allows each to
947 // be more readable. It will be good to keep these two in sync as
948 // much as possible.
949
950 assert_heap_not_locked_and_not_at_safepoint();
951 assert(is_humongous(word_size), "attempt_allocation_humongous() "
952 "should only be called for humongous allocations");
953
954 // Humongous objects can exhaust the heap quickly, so we should check if we
955 // need to start a marking cycle at each humongous object allocation. We do
956 // the check before we do the actual allocation. The reason for doing it
957 // before the allocation is that we avoid having to keep track of the newly
958 // allocated memory while we do a GC.
959 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
960 word_size)) {
961 collect(GCCause::_g1_humongous_allocation);
962 }
963
964 // We will loop until a) we manage to successfully perform the
965 // allocation or b) we successfully schedule a collection which
966 // fails to perform the allocation. b) is the only case when we'll
967 // return NULL.
968 HeapWord* result = NULL;
969 for (int try_count = 1; /* we'll return */; try_count += 1) {
970 bool should_try_gc;
971 uint gc_count_before;
972
973 {
974 MutexLockerEx x(Heap_lock);
975
976 // Given that humongous objects are not allocated in young
977 // regions, we'll first try to do the allocation without doing a
978 // collection hoping that there's enough space in the heap.
979 result = humongous_obj_allocate(word_size, AllocationContext::current());
980 if (result != NULL) {
981 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
982 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
983 return result;
984 }
985
986 if (GCLocker::is_active_and_needs_gc()) {
987 should_try_gc = false;
988 } else {
989 // The GCLocker may not be active but the GCLocker initiated
990 // GC may not yet have been performed (GCLocker::needs_gc()
991 // returns true). In this case we do not try this GC and
992 // wait until the GCLocker initiated GC is performed, and
993 // then retry the allocation.
994 if (GCLocker::needs_gc()) {
995 should_try_gc = false;
996 } else {
997 // Read the GC count while still holding the Heap_lock.
998 gc_count_before = total_collections();
999 should_try_gc = true;
1000 }
1001 }
1002 }
1003
1004 if (should_try_gc) {
1005 // If we failed to allocate the humongous object, we should try to
1006 // do a collection pause (if we're allowed) in case it reclaims
1007 // enough space for the allocation to succeed after the pause.
1008
1009 bool succeeded;
1010 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1011 GCCause::_g1_humongous_allocation);
1012 if (result != NULL) {
1013 assert(succeeded, "only way to get back a non-NULL result");
1014 return result;
1015 }
1016
1017 if (succeeded) {
1018 // If we get here we successfully scheduled a collection which
1019 // failed to allocate. No point in trying to allocate
1020 // further. We'll just return NULL.
1021 MutexLockerEx x(Heap_lock);
1022 *gc_count_before_ret = total_collections();
1023 return NULL;
1024 }
1025 } else {
1026 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1027 MutexLockerEx x(Heap_lock);
1028 *gc_count_before_ret = total_collections();
1029 return NULL;
1030 }
1031 // The GCLocker is either active or the GCLocker initiated
1032 // GC has not yet been performed. Stall until it is and
1033 // then retry the allocation.
1034 GCLocker::stall_until_clear();
1035 (*gclocker_retry_count_ret) += 1;
1036 }
1037
1038 // We can reach here if we were unsuccessful in scheduling a
1039 // collection (because another thread beat us to it) or if we were
1040 // stalled due to the GC locker. In either can we should retry the
1041 // allocation attempt in case another thread successfully
1042 // performed a collection and reclaimed enough space. Give a
1043 // warning if we seem to be looping forever.
1044
1045 if ((QueuedAllocationWarningCount > 0) &&
1046 (try_count % QueuedAllocationWarningCount == 0)) {
1047 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1048 "retries %d times", try_count);
1049 }
1050 }
1051
1052 ShouldNotReachHere();
1053 return NULL;
1054 }
1055
1056 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1057 AllocationContext_t context,
1058 bool expect_null_mutator_alloc_region) {
1059 assert_at_safepoint(true /* should_be_vm_thread */);
1060 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1061 "the current alloc region was unexpectedly found to be non-NULL");
1062
1063 if (!is_humongous(word_size)) {
1064 return _allocator->attempt_allocation_locked(word_size, context);
1065 } else {
1066 HeapWord* result = humongous_obj_allocate(word_size, context);
1067 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1068 collector_state()->set_initiate_conc_mark_if_possible(true);
1069 }
1070 return result;
1071 }
1072
1073 ShouldNotReachHere();
1074 }
1075
1076 class PostMCRemSetClearClosure: public HeapRegionClosure {
1077 G1CollectedHeap* _g1h;
1078 ModRefBarrierSet* _mr_bs;
1079 public:
1080 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1081 _g1h(g1h), _mr_bs(mr_bs) {}
1082
1083 bool doHeapRegion(HeapRegion* r) {
1084 HeapRegionRemSet* hrrs = r->rem_set();
1085
1086 _g1h->reset_gc_time_stamps(r);
1087
1088 if (r->is_continues_humongous()) {
1089 // We'll assert that the strong code root list and RSet is empty
1090 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1091 assert(hrrs->occupied() == 0, "RSet should be empty");
1092 } else {
1093 hrrs->clear();
1094 }
1095 // You might think here that we could clear just the cards
1096 // corresponding to the used region. But no: if we leave a dirty card
1097 // in a region we might allocate into, then it would prevent that card
1098 // from being enqueued, and cause it to be missed.
1099 // Re: the performance cost: we shouldn't be doing full GC anyway!
1100 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1101
1102 return false;
1103 }
1104 };
1105
1106 void G1CollectedHeap::clear_rsets_post_compaction() {
1107 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1108 heap_region_iterate(&rs_clear);
1109 }
1110
1111 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1112 G1CollectedHeap* _g1h;
1113 UpdateRSOopClosure _cl;
1114 public:
1115 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1116 _cl(g1->g1_rem_set(), worker_i),
1117 _g1h(g1)
1118 { }
1119
1120 bool doHeapRegion(HeapRegion* r) {
1121 if (!r->is_continues_humongous()) {
1122 _cl.set_from(r);
1123 r->oop_iterate(&_cl);
1124 }
1125 return false;
1126 }
1127 };
1128
1129 class ParRebuildRSTask: public AbstractGangTask {
1130 G1CollectedHeap* _g1;
1131 HeapRegionClaimer _hrclaimer;
1132
1133 public:
1134 ParRebuildRSTask(G1CollectedHeap* g1) :
1135 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1136
1137 void work(uint worker_id) {
1138 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1139 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1140 }
1141 };
1142
1143 class PostCompactionPrinterClosure: public HeapRegionClosure {
1144 private:
1145 G1HRPrinter* _hr_printer;
1146 public:
1147 bool doHeapRegion(HeapRegion* hr) {
1148 assert(!hr->is_young(), "not expecting to find young regions");
1149 _hr_printer->post_compaction(hr);
1150 return false;
1151 }
1152
1153 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1154 : _hr_printer(hr_printer) { }
1155 };
1156
1157 void G1CollectedHeap::print_hrm_post_compaction() {
1158 if (_hr_printer.is_active()) {
1159 PostCompactionPrinterClosure cl(hr_printer());
1160 heap_region_iterate(&cl);
1161 }
1162
1163 }
1164
1165 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1166 bool clear_all_soft_refs) {
1167 assert_at_safepoint(true /* should_be_vm_thread */);
1168
1169 if (GCLocker::check_active_before_gc()) {
1170 return false;
1171 }
1172
1173 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1174 gc_timer->register_gc_start();
1175
1176 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1177 GCIdMark gc_id_mark;
1178 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1179
1180 SvcGCMarker sgcm(SvcGCMarker::FULL);
1181 ResourceMark rm;
1182
1183 print_heap_before_gc();
1184 print_heap_regions();
1185 trace_heap_before_gc(gc_tracer);
1186
1187 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1188
1189 _verifier->verify_region_sets_optional();
1190
1191 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1192 collector_policy()->should_clear_all_soft_refs();
1193
1194 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1195
1196 {
1197 IsGCActiveMark x;
1198
1199 // Timing
1200 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1201 GCTraceCPUTime tcpu;
1202
1203 {
1204 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1205 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1206 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1207
1208 G1HeapTransition heap_transition(this);
1209 g1_policy()->record_full_collection_start();
1210
1211 // Note: When we have a more flexible GC logging framework that
1212 // allows us to add optional attributes to a GC log record we
1213 // could consider timing and reporting how long we wait in the
1214 // following two methods.
1215 wait_while_free_regions_coming();
1216 // If we start the compaction before the CM threads finish
1217 // scanning the root regions we might trip them over as we'll
1218 // be moving objects / updating references. So let's wait until
1219 // they are done. By telling them to abort, they should complete
1220 // early.
1221 _cm->root_regions()->abort();
1222 _cm->root_regions()->wait_until_scan_finished();
1223 append_secondary_free_list_if_not_empty_with_lock();
1224
1225 gc_prologue(true);
1226 increment_total_collections(true /* full gc */);
1227 increment_old_marking_cycles_started();
1228
1229 assert(used() == recalculate_used(), "Should be equal");
1230
1231 _verifier->verify_before_gc();
1232
1233 _verifier->check_bitmaps("Full GC Start");
1234 pre_full_gc_dump(gc_timer);
1235
1236 #if defined(COMPILER2) || INCLUDE_JVMCI
1237 DerivedPointerTable::clear();
1238 #endif
1239
1240 // Disable discovery and empty the discovered lists
1241 // for the CM ref processor.
1242 ref_processor_cm()->disable_discovery();
1243 ref_processor_cm()->abandon_partial_discovery();
1244 ref_processor_cm()->verify_no_references_recorded();
1245
1246 // Abandon current iterations of concurrent marking and concurrent
1247 // refinement, if any are in progress.
1248 concurrent_mark()->abort();
1249
1250 // Make sure we'll choose a new allocation region afterwards.
1251 _allocator->release_mutator_alloc_region();
1252 _allocator->abandon_gc_alloc_regions();
1253 g1_rem_set()->cleanupHRRS();
1254
1255 // We may have added regions to the current incremental collection
1256 // set between the last GC or pause and now. We need to clear the
1257 // incremental collection set and then start rebuilding it afresh
1258 // after this full GC.
1259 abandon_collection_set(collection_set());
1260
1261 tear_down_region_sets(false /* free_list_only */);
1262 collector_state()->set_gcs_are_young(true);
1263
1264 // See the comments in g1CollectedHeap.hpp and
1265 // G1CollectedHeap::ref_processing_init() about
1266 // how reference processing currently works in G1.
1267
1268 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1269 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1270
1271 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1272 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1273
1274 ref_processor_stw()->enable_discovery();
1275 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1276
1277 // Do collection work
1278 {
1279 HandleMark hm; // Discard invalid handles created during gc
1280 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1281 }
1282
1283 assert(num_free_regions() == 0, "we should not have added any free regions");
1284 rebuild_region_sets(false /* free_list_only */);
1285
1286 // Enqueue any discovered reference objects that have
1287 // not been removed from the discovered lists.
1288 ref_processor_stw()->enqueue_discovered_references();
1289
1290 #if defined(COMPILER2) || INCLUDE_JVMCI
1291 DerivedPointerTable::update_pointers();
1292 #endif
1293
1294 MemoryService::track_memory_usage();
1295
1296 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1297 ref_processor_stw()->verify_no_references_recorded();
1298
1299 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1300 ClassLoaderDataGraph::purge();
1301 MetaspaceAux::verify_metrics();
1302
1303 // Note: since we've just done a full GC, concurrent
1304 // marking is no longer active. Therefore we need not
1305 // re-enable reference discovery for the CM ref processor.
1306 // That will be done at the start of the next marking cycle.
1307 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1308 ref_processor_cm()->verify_no_references_recorded();
1309
1310 reset_gc_time_stamp();
1311 // Since everything potentially moved, we will clear all remembered
1312 // sets, and clear all cards. Later we will rebuild remembered
1313 // sets. We will also reset the GC time stamps of the regions.
1314 clear_rsets_post_compaction();
1315 check_gc_time_stamps();
1316
1317 resize_if_necessary_after_full_collection();
1318
1319 // We should do this after we potentially resize the heap so
1320 // that all the COMMIT / UNCOMMIT events are generated before
1321 // the compaction events.
1322 print_hrm_post_compaction();
1323
1324 if (_hot_card_cache->use_cache()) {
1325 _hot_card_cache->reset_card_counts();
1326 _hot_card_cache->reset_hot_cache();
1327 }
1328
1329 // Rebuild remembered sets of all regions.
1330 uint n_workers =
1331 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1332 workers()->active_workers(),
1333 Threads::number_of_non_daemon_threads());
1334 workers()->set_active_workers(n_workers);
1335
1336 ParRebuildRSTask rebuild_rs_task(this);
1337 workers()->run_task(&rebuild_rs_task);
1338
1339 // Rebuild the strong code root lists for each region
1340 rebuild_strong_code_roots();
1341
1342 if (true) { // FIXME
1343 MetaspaceGC::compute_new_size();
1344 }
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 // Discard all rset updates
1351 JavaThread::dirty_card_queue_set().abandon_logs();
1352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1353
1354 // At this point there should be no regions in the
1355 // entire heap tagged as young.
1356 assert(check_young_list_empty(), "young list should be empty at this point");
1357
1358 // Update the number of full collections that have been completed.
1359 increment_old_marking_cycles_completed(false /* concurrent */);
1360
1361 _hrm.verify_optional();
1362 _verifier->verify_region_sets_optional();
1363
1364 _verifier->verify_after_gc();
1365
1366 // Clear the previous marking bitmap, if needed for bitmap verification.
1367 // Note we cannot do this when we clear the next marking bitmap in
1368 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1369 // objects marked during a full GC against the previous bitmap.
1370 // But we need to clear it before calling check_bitmaps below since
1371 // the full GC has compacted objects and updated TAMS but not updated
1372 // the prev bitmap.
1373 if (G1VerifyBitmaps) {
1374 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1375 _cm->clear_prev_bitmap(workers());
1376 }
1377 _verifier->check_bitmaps("Full GC End");
1378
1379 // Start a new incremental collection set for the next pause
1380 collection_set()->start_incremental_building();
1381
1382 clear_cset_fast_test();
1383
1384 _allocator->init_mutator_alloc_region();
1385
1386 g1_policy()->record_full_collection_end();
1387
1388 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1389 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1390 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1391 // before any GC notifications are raised.
1392 g1mm()->update_sizes();
1393
1394 gc_epilogue(true);
1395
1396 heap_transition.print();
1397
1398 print_heap_after_gc();
1399 print_heap_regions();
1400 trace_heap_after_gc(gc_tracer);
1401
1402 post_full_gc_dump(gc_timer);
1403 }
1404
1405 gc_timer->register_gc_end();
1406 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1407 }
1408
1409 return true;
1410 }
1411
1412 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1413 // Currently, there is no facility in the do_full_collection(bool) API to notify
1414 // the caller that the collection did not succeed (e.g., because it was locked
1415 // out by the GC locker). So, right now, we'll ignore the return value.
1416 bool dummy = do_full_collection(true, /* explicit_gc */
1417 clear_all_soft_refs);
1418 }
1419
1420 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1421 // Include bytes that will be pre-allocated to support collections, as "used".
1422 const size_t used_after_gc = used();
1423 const size_t capacity_after_gc = capacity();
1424 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1425
1426 // This is enforced in arguments.cpp.
1427 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1428 "otherwise the code below doesn't make sense");
1429
1430 // We don't have floating point command-line arguments
1431 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1432 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1433 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1434 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1435
1436 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1437 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1438
1439 // We have to be careful here as these two calculations can overflow
1440 // 32-bit size_t's.
1441 double used_after_gc_d = (double) used_after_gc;
1442 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1443 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1444
1445 // Let's make sure that they are both under the max heap size, which
1446 // by default will make them fit into a size_t.
1447 double desired_capacity_upper_bound = (double) max_heap_size;
1448 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1449 desired_capacity_upper_bound);
1450 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1451 desired_capacity_upper_bound);
1452
1453 // We can now safely turn them into size_t's.
1454 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1455 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1456
1457 // This assert only makes sense here, before we adjust them
1458 // with respect to the min and max heap size.
1459 assert(minimum_desired_capacity <= maximum_desired_capacity,
1460 "minimum_desired_capacity = " SIZE_FORMAT ", "
1461 "maximum_desired_capacity = " SIZE_FORMAT,
1462 minimum_desired_capacity, maximum_desired_capacity);
1463
1464 // Should not be greater than the heap max size. No need to adjust
1465 // it with respect to the heap min size as it's a lower bound (i.e.,
1466 // we'll try to make the capacity larger than it, not smaller).
1467 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1468 // Should not be less than the heap min size. No need to adjust it
1469 // with respect to the heap max size as it's an upper bound (i.e.,
1470 // we'll try to make the capacity smaller than it, not greater).
1471 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1472
1473 if (capacity_after_gc < minimum_desired_capacity) {
1474 // Don't expand unless it's significant
1475 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1476
1477 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1478 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1479 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1480
1481 expand(expand_bytes);
1482
1483 // No expansion, now see if we want to shrink
1484 } else if (capacity_after_gc > maximum_desired_capacity) {
1485 // Capacity too large, compute shrinking size
1486 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1487
1488 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1489 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1490 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1491
1492 shrink(shrink_bytes);
1493 }
1494 }
1495
1496 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1497 AllocationContext_t context,
1498 bool do_gc,
1499 bool clear_all_soft_refs,
1500 bool expect_null_mutator_alloc_region,
1501 bool* gc_succeeded) {
1502 *gc_succeeded = true;
1503 // Let's attempt the allocation first.
1504 HeapWord* result =
1505 attempt_allocation_at_safepoint(word_size,
1506 context,
1507 expect_null_mutator_alloc_region);
1508 if (result != NULL) {
1509 assert(*gc_succeeded, "sanity");
1510 return result;
1511 }
1512
1513 // In a G1 heap, we're supposed to keep allocation from failing by
1514 // incremental pauses. Therefore, at least for now, we'll favor
1515 // expansion over collection. (This might change in the future if we can
1516 // do something smarter than full collection to satisfy a failed alloc.)
1517 result = expand_and_allocate(word_size, context);
1518 if (result != NULL) {
1519 assert(*gc_succeeded, "sanity");
1520 return result;
1521 }
1522
1523 if (do_gc) {
1524 // Expansion didn't work, we'll try to do a Full GC.
1525 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1526 clear_all_soft_refs);
1527 }
1528
1529 return NULL;
1530 }
1531
1532 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1533 AllocationContext_t context,
1534 bool* succeeded) {
1535 assert_at_safepoint(true /* should_be_vm_thread */);
1536
1537 // Attempts to allocate followed by Full GC.
1538 HeapWord* result =
1539 satisfy_failed_allocation_helper(word_size,
1540 context,
1541 true, /* do_gc */
1542 false, /* clear_all_soft_refs */
1543 false, /* expect_null_mutator_alloc_region */
1544 succeeded);
1545
1546 if (result != NULL || !*succeeded) {
1547 return result;
1548 }
1549
1550 // Attempts to allocate followed by Full GC that will collect all soft references.
1551 result = satisfy_failed_allocation_helper(word_size,
1552 context,
1553 true, /* do_gc */
1554 true, /* clear_all_soft_refs */
1555 true, /* expect_null_mutator_alloc_region */
1556 succeeded);
1557
1558 if (result != NULL || !*succeeded) {
1559 return result;
1560 }
1561
1562 // Attempts to allocate, no GC
1563 result = satisfy_failed_allocation_helper(word_size,
1564 context,
1565 false, /* do_gc */
1566 false, /* clear_all_soft_refs */
1567 true, /* expect_null_mutator_alloc_region */
1568 succeeded);
1569
1570 if (result != NULL) {
1571 assert(*succeeded, "sanity");
1572 return result;
1573 }
1574
1575 assert(!collector_policy()->should_clear_all_soft_refs(),
1576 "Flag should have been handled and cleared prior to this point");
1577
1578 // What else? We might try synchronous finalization later. If the total
1579 // space available is large enough for the allocation, then a more
1580 // complete compaction phase than we've tried so far might be
1581 // appropriate.
1582 assert(*succeeded, "sanity");
1583 return NULL;
1584 }
1585
1586 // Attempting to expand the heap sufficiently
1587 // to support an allocation of the given "word_size". If
1588 // successful, perform the allocation and return the address of the
1589 // allocated block, or else "NULL".
1590
1591 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1592 assert_at_safepoint(true /* should_be_vm_thread */);
1593
1594 _verifier->verify_region_sets_optional();
1595
1596 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1597 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1598 word_size * HeapWordSize);
1599
1600
1601 if (expand(expand_bytes)) {
1602 _hrm.verify_optional();
1603 _verifier->verify_region_sets_optional();
1604 return attempt_allocation_at_safepoint(word_size,
1605 context,
1606 false /* expect_null_mutator_alloc_region */);
1607 }
1608 return NULL;
1609 }
1610
1611 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1612 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1613 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1614 HeapRegion::GrainBytes);
1615
1616 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1617 expand_bytes, aligned_expand_bytes);
1618
1619 if (is_maximal_no_gc()) {
1620 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1621 return false;
1622 }
1623
1624 double expand_heap_start_time_sec = os::elapsedTime();
1625 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1626 assert(regions_to_expand > 0, "Must expand by at least one region");
1627
1628 uint expanded_by = _hrm.expand_by(regions_to_expand);
1629 if (expand_time_ms != NULL) {
1630 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1631 }
1632
1633 if (expanded_by > 0) {
1634 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1635 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1636 g1_policy()->record_new_heap_size(num_regions());
1637 } else {
1638 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1639
1640 // The expansion of the virtual storage space was unsuccessful.
1641 // Let's see if it was because we ran out of swap.
1642 if (G1ExitOnExpansionFailure &&
1643 _hrm.available() >= regions_to_expand) {
1644 // We had head room...
1645 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1646 }
1647 }
1648 return regions_to_expand > 0;
1649 }
1650
1651 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1652 size_t aligned_shrink_bytes =
1653 ReservedSpace::page_align_size_down(shrink_bytes);
1654 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1655 HeapRegion::GrainBytes);
1656 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1657
1658 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1659 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1660
1661
1662 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",
1663 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1664 if (num_regions_removed > 0) {
1665 g1_policy()->record_new_heap_size(num_regions());
1666 } else {
1667 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1668 }
1669 }
1670
1671 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1672 _verifier->verify_region_sets_optional();
1673
1674 // We should only reach here at the end of a Full GC which means we
1675 // should not not be holding to any GC alloc regions. The method
1676 // below will make sure of that and do any remaining clean up.
1677 _allocator->abandon_gc_alloc_regions();
1678
1679 // Instead of tearing down / rebuilding the free lists here, we
1680 // could instead use the remove_all_pending() method on free_list to
1681 // remove only the ones that we need to remove.
1682 tear_down_region_sets(true /* free_list_only */);
1683 shrink_helper(shrink_bytes);
1684 rebuild_region_sets(true /* free_list_only */);
1685
1686 _hrm.verify_optional();
1687 _verifier->verify_region_sets_optional();
1688 }
1689
1690 // Public methods.
1691
1692 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1693 CollectedHeap(),
1694 _collector_policy(collector_policy),
1695 _g1_policy(create_g1_policy()),
1696 _collection_set(this, _g1_policy),
1697 _dirty_card_queue_set(false),
1698 _is_alive_closure_cm(this),
1699 _is_alive_closure_stw(this),
1700 _ref_processor_cm(NULL),
1701 _ref_processor_stw(NULL),
1702 _bot(NULL),
1703 _hot_card_cache(NULL),
1704 _g1_rem_set(NULL),
1705 _cg1r(NULL),
1706 _g1mm(NULL),
1707 _refine_cte_cl(NULL),
1708 _preserved_marks_set(true /* in_c_heap */),
1709 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1710 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1711 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1712 _humongous_reclaim_candidates(),
1713 _has_humongous_reclaim_candidates(false),
1714 _archive_allocator(NULL),
1715 _free_regions_coming(false),
1716 _gc_time_stamp(0),
1717 _summary_bytes_used(0),
1718 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1719 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1720 _expand_heap_after_alloc_failure(true),
1721 _old_marking_cycles_started(0),
1722 _old_marking_cycles_completed(0),
1723 _in_cset_fast_test(),
1724 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1725 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1726
1727 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1728 /* are_GC_task_threads */true,
1729 /* are_ConcurrentGC_threads */false);
1730 _workers->initialize_workers();
1731 _verifier = new G1HeapVerifier(this);
1732
1733 _allocator = G1Allocator::create_allocator(this);
1734
1735 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1736
1737 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1738
1739 // Override the default _filler_array_max_size so that no humongous filler
1740 // objects are created.
1741 _filler_array_max_size = _humongous_object_threshold_in_words;
1742
1743 uint n_queues = ParallelGCThreads;
1744 _task_queues = new RefToScanQueueSet(n_queues);
1745
1746 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1747
1748 for (uint i = 0; i < n_queues; i++) {
1749 RefToScanQueue* q = new RefToScanQueue();
1750 q->initialize();
1751 _task_queues->register_queue(i, q);
1752 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1753 }
1754
1755 // Initialize the G1EvacuationFailureALot counters and flags.
1756 NOT_PRODUCT(reset_evacuation_should_fail();)
1757
1758 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1759 }
1760
1761 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1762 size_t size,
1763 size_t translation_factor) {
1764 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1765 // Allocate a new reserved space, preferring to use large pages.
1766 ReservedSpace rs(size, preferred_page_size);
1767 G1RegionToSpaceMapper* result =
1768 G1RegionToSpaceMapper::create_mapper(rs,
1769 size,
1770 rs.alignment(),
1771 HeapRegion::GrainBytes,
1772 translation_factor,
1773 mtGC);
1774
1775 os::trace_page_sizes_for_requested_size(description,
1776 size,
1777 preferred_page_size,
1778 rs.alignment(),
1779 rs.base(),
1780 rs.size());
1781
1782 return result;
1783 }
1784
1785 jint G1CollectedHeap::initialize() {
1786 CollectedHeap::pre_initialize();
1787 os::enable_vtime();
1788
1789 // Necessary to satisfy locking discipline assertions.
1790
1791 MutexLocker x(Heap_lock);
1792
1793 // While there are no constraints in the GC code that HeapWordSize
1794 // be any particular value, there are multiple other areas in the
1795 // system which believe this to be true (e.g. oop->object_size in some
1796 // cases incorrectly returns the size in wordSize units rather than
1797 // HeapWordSize).
1798 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1799
1800 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1801 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1802 size_t heap_alignment = collector_policy()->heap_alignment();
1803
1804 // Ensure that the sizes are properly aligned.
1805 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1806 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1807 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1808
1809 _refine_cte_cl = new RefineCardTableEntryClosure();
1810
1811 jint ecode = JNI_OK;
1812 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1813 if (_cg1r == NULL) {
1814 return ecode;
1815 }
1816
1817 // Reserve the maximum.
1818
1819 // When compressed oops are enabled, the preferred heap base
1820 // is calculated by subtracting the requested size from the
1821 // 32Gb boundary and using the result as the base address for
1822 // heap reservation. If the requested size is not aligned to
1823 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1824 // into the ReservedHeapSpace constructor) then the actual
1825 // base of the reserved heap may end up differing from the
1826 // address that was requested (i.e. the preferred heap base).
1827 // If this happens then we could end up using a non-optimal
1828 // compressed oops mode.
1829
1830 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1831 heap_alignment);
1832
1833 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1834
1835 // Create the barrier set for the entire reserved region.
1836 G1SATBCardTableLoggingModRefBS* bs
1837 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1838 bs->initialize();
1839 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1840 set_barrier_set(bs);
1841
1842 // Create the hot card cache.
1843 _hot_card_cache = new G1HotCardCache(this);
1844
1845 // Also create a G1 rem set.
1846 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1847
1848 // Carve out the G1 part of the heap.
1849 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1850 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1851 G1RegionToSpaceMapper* heap_storage =
1852 G1RegionToSpaceMapper::create_mapper(g1_rs,
1853 g1_rs.size(),
1854 page_size,
1855 HeapRegion::GrainBytes,
1856 1,
1857 mtJavaHeap);
1858 os::trace_page_sizes("Heap",
1859 collector_policy()->min_heap_byte_size(),
1860 max_byte_size,
1861 page_size,
1862 heap_rs.base(),
1863 heap_rs.size());
1864 heap_storage->set_mapping_changed_listener(&_listener);
1865
1866 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1867 G1RegionToSpaceMapper* bot_storage =
1868 create_aux_memory_mapper("Block Offset Table",
1869 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1870 G1BlockOffsetTable::heap_map_factor());
1871
1872 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1873 G1RegionToSpaceMapper* cardtable_storage =
1874 create_aux_memory_mapper("Card Table",
1875 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1876 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1877
1878 G1RegionToSpaceMapper* card_counts_storage =
1879 create_aux_memory_mapper("Card Counts Table",
1880 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1881 G1CardCounts::heap_map_factor());
1882
1883 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1884 G1RegionToSpaceMapper* prev_bitmap_storage =
1885 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1886 G1RegionToSpaceMapper* next_bitmap_storage =
1887 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1888
1889 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1890 g1_barrier_set()->initialize(cardtable_storage);
1891 // Do later initialization work for concurrent refinement.
1892 _hot_card_cache->initialize(card_counts_storage);
1893
1894 // 6843694 - ensure that the maximum region index can fit
1895 // in the remembered set structures.
1896 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1897 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1898
1899 g1_rem_set()->initialize(max_capacity(), max_regions());
1900
1901 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1902 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1903 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1904 "too many cards per region");
1905
1906 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1907
1908 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1909
1910 {
1911 HeapWord* start = _hrm.reserved().start();
1912 HeapWord* end = _hrm.reserved().end();
1913 size_t granularity = HeapRegion::GrainBytes;
1914
1915 _in_cset_fast_test.initialize(start, end, granularity);
1916 _humongous_reclaim_candidates.initialize(start, end, granularity);
1917 }
1918
1919 // Create the G1ConcurrentMark data structure and thread.
1920 // (Must do this late, so that "max_regions" is defined.)
1921 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1922 if (_cm == NULL || !_cm->completed_initialization()) {
1923 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1924 return JNI_ENOMEM;
1925 }
1926 _cmThread = _cm->cmThread();
1927
1928 // Now expand into the initial heap size.
1929 if (!expand(init_byte_size)) {
1930 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1931 return JNI_ENOMEM;
1932 }
1933
1934 // Perform any initialization actions delegated to the policy.
1935 g1_policy()->init(this, &_collection_set);
1936
1937 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1938 SATB_Q_FL_lock,
1939 G1SATBProcessCompletedThreshold,
1940 Shared_SATB_Q_lock);
1941
1942 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1943 DirtyCardQ_CBL_mon,
1944 DirtyCardQ_FL_lock,
1945 (int)concurrent_g1_refine()->yellow_zone(),
1946 (int)concurrent_g1_refine()->red_zone(),
1947 Shared_DirtyCardQ_lock,
1948 NULL, // fl_owner
1949 true); // init_free_ids
1950
1951 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1952 DirtyCardQ_CBL_mon,
1953 DirtyCardQ_FL_lock,
1954 -1, // never trigger processing
1955 -1, // no limit on length
1956 Shared_DirtyCardQ_lock,
1957 &JavaThread::dirty_card_queue_set());
1958
1959 // Here we allocate the dummy HeapRegion that is required by the
1960 // G1AllocRegion class.
1961 HeapRegion* dummy_region = _hrm.get_dummy_region();
1962
1963 // We'll re-use the same region whether the alloc region will
1964 // require BOT updates or not and, if it doesn't, then a non-young
1965 // region will complain that it cannot support allocations without
1966 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1967 dummy_region->set_eden();
1968 // Make sure it's full.
1969 dummy_region->set_top(dummy_region->end());
1970 G1AllocRegion::setup(this, dummy_region);
1971
1972 _allocator->init_mutator_alloc_region();
1973
1974 // Do create of the monitoring and management support so that
1975 // values in the heap have been properly initialized.
1976 _g1mm = new G1MonitoringSupport(this);
1977
1978 G1StringDedup::initialize();
1979
1980 _preserved_marks_set.init(ParallelGCThreads);
1981
1982 _collection_set.set_max_length(max_regions());
1983
1984 return JNI_OK;
1985 }
1986
1987 void G1CollectedHeap::stop() {
1988 // Stop all concurrent threads. We do this to make sure these threads
1989 // do not continue to execute and access resources (e.g. logging)
1990 // that are destroyed during shutdown.
1991 _cg1r->stop();
1992 _cmThread->stop();
1993 if (G1StringDedup::is_enabled()) {
1994 G1StringDedup::stop();
1995 }
1996 }
1997
1998 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1999 return HeapRegion::max_region_size();
2000 }
2001
2002 void G1CollectedHeap::post_initialize() {
2003 ref_processing_init();
2004 }
2005
2006 void G1CollectedHeap::ref_processing_init() {
2007 // Reference processing in G1 currently works as follows:
2008 //
2009 // * There are two reference processor instances. One is
2010 // used to record and process discovered references
2011 // during concurrent marking; the other is used to
2012 // record and process references during STW pauses
2013 // (both full and incremental).
2014 // * Both ref processors need to 'span' the entire heap as
2015 // the regions in the collection set may be dotted around.
2016 //
2017 // * For the concurrent marking ref processor:
2018 // * Reference discovery is enabled at initial marking.
2019 // * Reference discovery is disabled and the discovered
2020 // references processed etc during remarking.
2021 // * Reference discovery is MT (see below).
2022 // * Reference discovery requires a barrier (see below).
2023 // * Reference processing may or may not be MT
2024 // (depending on the value of ParallelRefProcEnabled
2025 // and ParallelGCThreads).
2026 // * A full GC disables reference discovery by the CM
2027 // ref processor and abandons any entries on it's
2028 // discovered lists.
2029 //
2030 // * For the STW processor:
2031 // * Non MT discovery is enabled at the start of a full GC.
2032 // * Processing and enqueueing during a full GC is non-MT.
2033 // * During a full GC, references are processed after marking.
2034 //
2035 // * Discovery (may or may not be MT) is enabled at the start
2036 // of an incremental evacuation pause.
2037 // * References are processed near the end of a STW evacuation pause.
2038 // * For both types of GC:
2039 // * Discovery is atomic - i.e. not concurrent.
2040 // * Reference discovery will not need a barrier.
2041
2042 MemRegion mr = reserved_region();
2043
2044 // Concurrent Mark ref processor
2045 _ref_processor_cm =
2046 new ReferenceProcessor(mr, // span
2047 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2048 // mt processing
2049 ParallelGCThreads,
2050 // degree of mt processing
2051 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2052 // mt discovery
2053 MAX2(ParallelGCThreads, ConcGCThreads),
2054 // degree of mt discovery
2055 false,
2056 // Reference discovery is not atomic
2057 &_is_alive_closure_cm);
2058 // is alive closure
2059 // (for efficiency/performance)
2060
2061 // STW ref processor
2062 _ref_processor_stw =
2063 new ReferenceProcessor(mr, // span
2064 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2065 // mt processing
2066 ParallelGCThreads,
2067 // degree of mt processing
2068 (ParallelGCThreads > 1),
2069 // mt discovery
2070 ParallelGCThreads,
2071 // degree of mt discovery
2072 true,
2073 // Reference discovery is atomic
2074 &_is_alive_closure_stw);
2075 // is alive closure
2076 // (for efficiency/performance)
2077 }
2078
2079 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2080 return _collector_policy;
2081 }
2082
2083 size_t G1CollectedHeap::capacity() const {
2084 return _hrm.length() * HeapRegion::GrainBytes;
2085 }
2086
2087 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2088 hr->reset_gc_time_stamp();
2089 }
2090
2091 #ifndef PRODUCT
2092
2093 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2094 private:
2095 unsigned _gc_time_stamp;
2096 bool _failures;
2097
2098 public:
2099 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2100 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2101
2102 virtual bool doHeapRegion(HeapRegion* hr) {
2103 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2104 if (_gc_time_stamp != region_gc_time_stamp) {
2105 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2106 region_gc_time_stamp, _gc_time_stamp);
2107 _failures = true;
2108 }
2109 return false;
2110 }
2111
2112 bool failures() { return _failures; }
2113 };
2114
2115 void G1CollectedHeap::check_gc_time_stamps() {
2116 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2117 heap_region_iterate(&cl);
2118 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2119 }
2120 #endif // PRODUCT
2121
2122 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2123 _hot_card_cache->drain(cl, worker_i);
2124 }
2125
2126 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2127 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2128 size_t n_completed_buffers = 0;
2129 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2130 n_completed_buffers++;
2131 }
2132 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2133 dcqs.clear_n_completed_buffers();
2134 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2135 }
2136
2137 // Computes the sum of the storage used by the various regions.
2138 size_t G1CollectedHeap::used() const {
2139 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2140 if (_archive_allocator != NULL) {
2141 result += _archive_allocator->used();
2142 }
2143 return result;
2144 }
2145
2146 size_t G1CollectedHeap::used_unlocked() const {
2147 return _summary_bytes_used;
2148 }
2149
2150 class SumUsedClosure: public HeapRegionClosure {
2151 size_t _used;
2152 public:
2153 SumUsedClosure() : _used(0) {}
2154 bool doHeapRegion(HeapRegion* r) {
2155 _used += r->used();
2156 return false;
2157 }
2158 size_t result() { return _used; }
2159 };
2160
2161 size_t G1CollectedHeap::recalculate_used() const {
2162 double recalculate_used_start = os::elapsedTime();
2163
2164 SumUsedClosure blk;
2165 heap_region_iterate(&blk);
2166
2167 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2168 return blk.result();
2169 }
2170
2171 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2172 switch (cause) {
2173 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2174 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2175 case GCCause::_update_allocation_context_stats_inc: return true;
2176 case GCCause::_wb_conc_mark: return true;
2177 default : return false;
2178 }
2179 }
2180
2181 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2182 switch (cause) {
2183 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2184 case GCCause::_g1_humongous_allocation: return true;
2185 default: return is_user_requested_concurrent_full_gc(cause);
2186 }
2187 }
2188
2189 #ifndef PRODUCT
2190 void G1CollectedHeap::allocate_dummy_regions() {
2191 // Let's fill up most of the region
2192 size_t word_size = HeapRegion::GrainWords - 1024;
2193 // And as a result the region we'll allocate will be humongous.
2194 guarantee(is_humongous(word_size), "sanity");
2195
2196 // _filler_array_max_size is set to humongous object threshold
2197 // but temporarily change it to use CollectedHeap::fill_with_object().
2198 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2199
2200 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2201 // Let's use the existing mechanism for the allocation
2202 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2203 AllocationContext::system());
2204 if (dummy_obj != NULL) {
2205 MemRegion mr(dummy_obj, word_size);
2206 CollectedHeap::fill_with_object(mr);
2207 } else {
2208 // If we can't allocate once, we probably cannot allocate
2209 // again. Let's get out of the loop.
2210 break;
2211 }
2212 }
2213 }
2214 #endif // !PRODUCT
2215
2216 void G1CollectedHeap::increment_old_marking_cycles_started() {
2217 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2218 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2219 "Wrong marking cycle count (started: %d, completed: %d)",
2220 _old_marking_cycles_started, _old_marking_cycles_completed);
2221
2222 _old_marking_cycles_started++;
2223 }
2224
2225 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2226 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2227
2228 // We assume that if concurrent == true, then the caller is a
2229 // concurrent thread that was joined the Suspendible Thread
2230 // Set. If there's ever a cheap way to check this, we should add an
2231 // assert here.
2232
2233 // Given that this method is called at the end of a Full GC or of a
2234 // concurrent cycle, and those can be nested (i.e., a Full GC can
2235 // interrupt a concurrent cycle), the number of full collections
2236 // completed should be either one (in the case where there was no
2237 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2238 // behind the number of full collections started.
2239
2240 // This is the case for the inner caller, i.e. a Full GC.
2241 assert(concurrent ||
2242 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2243 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2244 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2245 "is inconsistent with _old_marking_cycles_completed = %u",
2246 _old_marking_cycles_started, _old_marking_cycles_completed);
2247
2248 // This is the case for the outer caller, i.e. the concurrent cycle.
2249 assert(!concurrent ||
2250 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2251 "for outer caller (concurrent cycle): "
2252 "_old_marking_cycles_started = %u "
2253 "is inconsistent with _old_marking_cycles_completed = %u",
2254 _old_marking_cycles_started, _old_marking_cycles_completed);
2255
2256 _old_marking_cycles_completed += 1;
2257
2258 // We need to clear the "in_progress" flag in the CM thread before
2259 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2260 // is set) so that if a waiter requests another System.gc() it doesn't
2261 // incorrectly see that a marking cycle is still in progress.
2262 if (concurrent) {
2263 _cmThread->set_idle();
2264 }
2265
2266 // This notify_all() will ensure that a thread that called
2267 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2268 // and it's waiting for a full GC to finish will be woken up. It is
2269 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2270 FullGCCount_lock->notify_all();
2271 }
2272
2273 void G1CollectedHeap::collect(GCCause::Cause cause) {
2274 assert_heap_not_locked();
2275
2276 uint gc_count_before;
2277 uint old_marking_count_before;
2278 uint full_gc_count_before;
2279 bool retry_gc;
2280
2281 do {
2282 retry_gc = false;
2283
2284 {
2285 MutexLocker ml(Heap_lock);
2286
2287 // Read the GC count while holding the Heap_lock
2288 gc_count_before = total_collections();
2289 full_gc_count_before = total_full_collections();
2290 old_marking_count_before = _old_marking_cycles_started;
2291 }
2292
2293 if (should_do_concurrent_full_gc(cause)) {
2294 // Schedule an initial-mark evacuation pause that will start a
2295 // concurrent cycle. We're setting word_size to 0 which means that
2296 // we are not requesting a post-GC allocation.
2297 VM_G1IncCollectionPause op(gc_count_before,
2298 0, /* word_size */
2299 true, /* should_initiate_conc_mark */
2300 g1_policy()->max_pause_time_ms(),
2301 cause);
2302 op.set_allocation_context(AllocationContext::current());
2303
2304 VMThread::execute(&op);
2305 if (!op.pause_succeeded()) {
2306 if (old_marking_count_before == _old_marking_cycles_started) {
2307 retry_gc = op.should_retry_gc();
2308 } else {
2309 // A Full GC happened while we were trying to schedule the
2310 // initial-mark GC. No point in starting a new cycle given
2311 // that the whole heap was collected anyway.
2312 }
2313
2314 if (retry_gc) {
2315 if (GCLocker::is_active_and_needs_gc()) {
2316 GCLocker::stall_until_clear();
2317 }
2318 }
2319 }
2320 } else {
2321 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2322 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2323
2324 // Schedule a standard evacuation pause. We're setting word_size
2325 // to 0 which means that we are not requesting a post-GC allocation.
2326 VM_G1IncCollectionPause op(gc_count_before,
2327 0, /* word_size */
2328 false, /* should_initiate_conc_mark */
2329 g1_policy()->max_pause_time_ms(),
2330 cause);
2331 VMThread::execute(&op);
2332 } else {
2333 // Schedule a Full GC.
2334 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2335 VMThread::execute(&op);
2336 }
2337 }
2338 } while (retry_gc);
2339 }
2340
2341 bool G1CollectedHeap::is_in(const void* p) const {
2342 if (_hrm.reserved().contains(p)) {
2343 // Given that we know that p is in the reserved space,
2344 // heap_region_containing() should successfully
2345 // return the containing region.
2346 HeapRegion* hr = heap_region_containing(p);
2347 return hr->is_in(p);
2348 } else {
2349 return false;
2350 }
2351 }
2352
2353 #ifdef ASSERT
2354 bool G1CollectedHeap::is_in_exact(const void* p) const {
2355 bool contains = reserved_region().contains(p);
2356 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2357 if (contains && available) {
2358 return true;
2359 } else {
2360 return false;
2361 }
2362 }
2363 #endif
2364
2365 bool G1CollectedHeap::obj_in_cs(oop obj) {
2366 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2367 return r != NULL && r->in_collection_set();
2368 }
2369
2370 // Iteration functions.
2371
2372 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2373
2374 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2375 ExtendedOopClosure* _cl;
2376 public:
2377 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2378 bool doHeapRegion(HeapRegion* r) {
2379 if (!r->is_continues_humongous()) {
2380 r->oop_iterate(_cl);
2381 }
2382 return false;
2383 }
2384 };
2385
2386 // Iterates an ObjectClosure over all objects within a HeapRegion.
2387
2388 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2389 ObjectClosure* _cl;
2390 public:
2391 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2392 bool doHeapRegion(HeapRegion* r) {
2393 if (!r->is_continues_humongous()) {
2394 r->object_iterate(_cl);
2395 }
2396 return false;
2397 }
2398 };
2399
2400 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2401 IterateObjectClosureRegionClosure blk(cl);
2402 heap_region_iterate(&blk);
2403 }
2404
2405 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2406 _hrm.iterate(cl);
2407 }
2408
2409 void
2410 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2411 uint worker_id,
2412 HeapRegionClaimer *hrclaimer,
2413 bool concurrent) const {
2414 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2415 }
2416
2417 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2418 _collection_set.iterate(cl);
2419 }
2420
2421 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2422 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2423 }
2424
2425 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2426 HeapRegion* result = _hrm.next_region_in_heap(from);
2427 while (result != NULL && result->is_pinned()) {
2428 result = _hrm.next_region_in_heap(result);
2429 }
2430 return result;
2431 }
2432
2433 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2434 HeapRegion* hr = heap_region_containing(addr);
2435 return hr->block_start(addr);
2436 }
2437
2438 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2439 HeapRegion* hr = heap_region_containing(addr);
2440 return hr->block_size(addr);
2441 }
2442
2443 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2444 HeapRegion* hr = heap_region_containing(addr);
2445 return hr->block_is_obj(addr);
2446 }
2447
2448 bool G1CollectedHeap::supports_tlab_allocation() const {
2449 return true;
2450 }
2451
2452 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2453 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2454 }
2455
2456 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2457 return _eden.length() * HeapRegion::GrainBytes;
2458 }
2459
2460 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2461 // must be equal to the humongous object limit.
2462 size_t G1CollectedHeap::max_tlab_size() const {
2463 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2464 }
2465
2466 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2467 AllocationContext_t context = AllocationContext::current();
2468 return _allocator->unsafe_max_tlab_alloc(context);
2469 }
2470
2471 size_t G1CollectedHeap::max_capacity() const {
2472 return _hrm.reserved().byte_size();
2473 }
2474
2475 jlong G1CollectedHeap::millis_since_last_gc() {
2476 // assert(false, "NYI");
2477 return 0;
2478 }
2479
2480 void G1CollectedHeap::prepare_for_verify() {
2481 _verifier->prepare_for_verify();
2482 }
2483
2484 void G1CollectedHeap::verify(VerifyOption vo) {
2485 _verifier->verify(vo);
2486 }
2487
2488 class PrintRegionClosure: public HeapRegionClosure {
2489 outputStream* _st;
2490 public:
2491 PrintRegionClosure(outputStream* st) : _st(st) {}
2492 bool doHeapRegion(HeapRegion* r) {
2493 r->print_on(_st);
2494 return false;
2495 }
2496 };
2497
2498 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2499 const HeapRegion* hr,
2500 const VerifyOption vo) const {
2501 switch (vo) {
2502 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2503 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2504 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2505 default: ShouldNotReachHere();
2506 }
2507 return false; // keep some compilers happy
2508 }
2509
2510 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2511 const VerifyOption vo) const {
2512 switch (vo) {
2513 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2514 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2515 case VerifyOption_G1UseMarkWord: {
2516 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2517 return !obj->is_gc_marked() && !hr->is_archive();
2518 }
2519 default: ShouldNotReachHere();
2520 }
2521 return false; // keep some compilers happy
2522 }
2523
2524 void G1CollectedHeap::print_heap_regions() const {
2525 Log(gc, heap, region) log;
2526 if (log.is_trace()) {
2527 ResourceMark rm;
2528 print_regions_on(log.trace_stream());
2529 }
2530 }
2531
2532 void G1CollectedHeap::print_on(outputStream* st) const {
2533 st->print(" %-20s", "garbage-first heap");
2534 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2535 capacity()/K, used_unlocked()/K);
2536 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2537 p2i(_hrm.reserved().start()),
2538 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2539 p2i(_hrm.reserved().end()));
2540 st->cr();
2541 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2542 uint young_regions = young_regions_count();
2543 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2544 (size_t) young_regions * HeapRegion::GrainBytes / K);
2545 uint survivor_regions = survivor_regions_count();
2546 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2547 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2548 st->cr();
2549 MetaspaceAux::print_on(st);
2550 }
2551
2552 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2553 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2554 "HS=humongous(starts), HC=humongous(continues), "
2555 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2556 "AC=allocation context, "
2557 "TAMS=top-at-mark-start (previous, next)");
2558 PrintRegionClosure blk(st);
2559 heap_region_iterate(&blk);
2560 }
2561
2562 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2563 print_on(st);
2564
2565 // Print the per-region information.
2566 print_regions_on(st);
2567 }
2568
2569 void G1CollectedHeap::print_on_error(outputStream* st) const {
2570 this->CollectedHeap::print_on_error(st);
2571
2572 if (_cm != NULL) {
2573 st->cr();
2574 _cm->print_on_error(st);
2575 }
2576 }
2577
2578 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2579 workers()->print_worker_threads_on(st);
2580 _cmThread->print_on(st);
2581 st->cr();
2582 _cm->print_worker_threads_on(st);
2583 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2584 if (G1StringDedup::is_enabled()) {
2585 G1StringDedup::print_worker_threads_on(st);
2586 }
2587 }
2588
2589 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2590 workers()->threads_do(tc);
2591 tc->do_thread(_cmThread);
2592 _cm->threads_do(tc);
2593 _cg1r->threads_do(tc); // also iterates over the sample thread
2594 if (G1StringDedup::is_enabled()) {
2595 G1StringDedup::threads_do(tc);
2596 }
2597 }
2598
2599 void G1CollectedHeap::print_tracing_info() const {
2600 g1_rem_set()->print_summary_info();
2601 concurrent_mark()->print_summary_info();
2602 }
2603
2604 #ifndef PRODUCT
2605 // Helpful for debugging RSet issues.
2606
2607 class PrintRSetsClosure : public HeapRegionClosure {
2608 private:
2609 const char* _msg;
2610 size_t _occupied_sum;
2611
2612 public:
2613 bool doHeapRegion(HeapRegion* r) {
2614 HeapRegionRemSet* hrrs = r->rem_set();
2615 size_t occupied = hrrs->occupied();
2616 _occupied_sum += occupied;
2617
2618 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2619 if (occupied == 0) {
2620 tty->print_cr(" RSet is empty");
2621 } else {
2622 hrrs->print();
2623 }
2624 tty->print_cr("----------");
2625 return false;
2626 }
2627
2628 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2629 tty->cr();
2630 tty->print_cr("========================================");
2631 tty->print_cr("%s", msg);
2632 tty->cr();
2633 }
2634
2635 ~PrintRSetsClosure() {
2636 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2637 tty->print_cr("========================================");
2638 tty->cr();
2639 }
2640 };
2641
2642 void G1CollectedHeap::print_cset_rsets() {
2643 PrintRSetsClosure cl("Printing CSet RSets");
2644 collection_set_iterate(&cl);
2645 }
2646
2647 void G1CollectedHeap::print_all_rsets() {
2648 PrintRSetsClosure cl("Printing All RSets");;
2649 heap_region_iterate(&cl);
2650 }
2651 #endif // PRODUCT
2652
2653 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2654
2655 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2656 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2657 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2658
2659 size_t eden_capacity_bytes =
2660 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2661
2662 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2663 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2664 eden_capacity_bytes, survivor_used_bytes, num_regions());
2665 }
2666
2667 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2668 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2669 stats->unused(), stats->used(), stats->region_end_waste(),
2670 stats->regions_filled(), stats->direct_allocated(),
2671 stats->failure_used(), stats->failure_waste());
2672 }
2673
2674 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2675 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2676 gc_tracer->report_gc_heap_summary(when, heap_summary);
2677
2678 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2679 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2680 }
2681
2682 G1CollectedHeap* G1CollectedHeap::heap() {
2683 CollectedHeap* heap = Universe::heap();
2684 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2685 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2686 return (G1CollectedHeap*)heap;
2687 }
2688
2689 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2690 // always_do_update_barrier = false;
2691 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2692 // Fill TLAB's and such
2693 accumulate_statistics_all_tlabs();
2694 ensure_parsability(true);
2695
2696 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2697 }
2698
2699 void G1CollectedHeap::gc_epilogue(bool full) {
2700 // we are at the end of the GC. Total collections has already been increased.
2701 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2702
2703 // FIXME: what is this about?
2704 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2705 // is set.
2706 #if defined(COMPILER2) || INCLUDE_JVMCI
2707 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2708 #endif
2709 // always_do_update_barrier = true;
2710
2711 resize_all_tlabs();
2712 allocation_context_stats().update(full);
2713
2714 // We have just completed a GC. Update the soft reference
2715 // policy with the new heap occupancy
2716 Universe::update_heap_info_at_gc();
2717 }
2718
2719 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2720 uint gc_count_before,
2721 bool* succeeded,
2722 GCCause::Cause gc_cause) {
2723 assert_heap_not_locked_and_not_at_safepoint();
2724 VM_G1IncCollectionPause op(gc_count_before,
2725 word_size,
2726 false, /* should_initiate_conc_mark */
2727 g1_policy()->max_pause_time_ms(),
2728 gc_cause);
2729
2730 op.set_allocation_context(AllocationContext::current());
2731 VMThread::execute(&op);
2732
2733 HeapWord* result = op.result();
2734 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2735 assert(result == NULL || ret_succeeded,
2736 "the result should be NULL if the VM did not succeed");
2737 *succeeded = ret_succeeded;
2738
2739 assert_heap_not_locked();
2740 return result;
2741 }
2742
2743 void
2744 G1CollectedHeap::doConcurrentMark() {
2745 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2746 if (!_cmThread->in_progress()) {
2747 _cmThread->set_started();
2748 CGC_lock->notify();
2749 }
2750 }
2751
2752 size_t G1CollectedHeap::pending_card_num() {
2753 size_t extra_cards = 0;
2754 JavaThread *curr = Threads::first();
2755 while (curr != NULL) {
2756 DirtyCardQueue& dcq = curr->dirty_card_queue();
2757 extra_cards += dcq.size();
2758 curr = curr->next();
2759 }
2760 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2761 size_t buffer_size = dcqs.buffer_size();
2762 size_t buffer_num = dcqs.completed_buffers_num();
2763
2764 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2765 // in bytes - not the number of 'entries'. We need to convert
2766 // into a number of cards.
2767 return (buffer_size * buffer_num + extra_cards) / oopSize;
2768 }
2769
2770 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2771 private:
2772 size_t _total_humongous;
2773 size_t _candidate_humongous;
2774
2775 DirtyCardQueue _dcq;
2776
2777 // We don't nominate objects with many remembered set entries, on
2778 // the assumption that such objects are likely still live.
2779 bool is_remset_small(HeapRegion* region) const {
2780 HeapRegionRemSet* const rset = region->rem_set();
2781 return G1EagerReclaimHumongousObjectsWithStaleRefs
2782 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2783 : rset->is_empty();
2784 }
2785
2786 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2787 assert(region->is_starts_humongous(), "Must start a humongous object");
2788
2789 oop obj = oop(region->bottom());
2790
2791 // Dead objects cannot be eager reclaim candidates. Due to class
2792 // unloading it is unsafe to query their classes so we return early.
2793 if (heap->is_obj_dead(obj, region)) {
2794 return false;
2795 }
2796
2797 // Candidate selection must satisfy the following constraints
2798 // while concurrent marking is in progress:
2799 //
2800 // * In order to maintain SATB invariants, an object must not be
2801 // reclaimed if it was allocated before the start of marking and
2802 // has not had its references scanned. Such an object must have
2803 // its references (including type metadata) scanned to ensure no
2804 // live objects are missed by the marking process. Objects
2805 // allocated after the start of concurrent marking don't need to
2806 // be scanned.
2807 //
2808 // * An object must not be reclaimed if it is on the concurrent
2809 // mark stack. Objects allocated after the start of concurrent
2810 // marking are never pushed on the mark stack.
2811 //
2812 // Nominating only objects allocated after the start of concurrent
2813 // marking is sufficient to meet both constraints. This may miss
2814 // some objects that satisfy the constraints, but the marking data
2815 // structures don't support efficiently performing the needed
2816 // additional tests or scrubbing of the mark stack.
2817 //
2818 // However, we presently only nominate is_typeArray() objects.
2819 // A humongous object containing references induces remembered
2820 // set entries on other regions. In order to reclaim such an
2821 // object, those remembered sets would need to be cleaned up.
2822 //
2823 // We also treat is_typeArray() objects specially, allowing them
2824 // to be reclaimed even if allocated before the start of
2825 // concurrent mark. For this we rely on mark stack insertion to
2826 // exclude is_typeArray() objects, preventing reclaiming an object
2827 // that is in the mark stack. We also rely on the metadata for
2828 // such objects to be built-in and so ensured to be kept live.
2829 // Frequent allocation and drop of large binary blobs is an
2830 // important use case for eager reclaim, and this special handling
2831 // may reduce needed headroom.
2832
2833 return obj->is_typeArray() && is_remset_small(region);
2834 }
2835
2836 public:
2837 RegisterHumongousWithInCSetFastTestClosure()
2838 : _total_humongous(0),
2839 _candidate_humongous(0),
2840 _dcq(&JavaThread::dirty_card_queue_set()) {
2841 }
2842
2843 virtual bool doHeapRegion(HeapRegion* r) {
2844 if (!r->is_starts_humongous()) {
2845 return false;
2846 }
2847 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2848
2849 bool is_candidate = humongous_region_is_candidate(g1h, r);
2850 uint rindex = r->hrm_index();
2851 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2852 if (is_candidate) {
2853 _candidate_humongous++;
2854 g1h->register_humongous_region_with_cset(rindex);
2855 // Is_candidate already filters out humongous object with large remembered sets.
2856 // If we have a humongous object with a few remembered sets, we simply flush these
2857 // remembered set entries into the DCQS. That will result in automatic
2858 // re-evaluation of their remembered set entries during the following evacuation
2859 // phase.
2860 if (!r->rem_set()->is_empty()) {
2861 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2862 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2863 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2864 HeapRegionRemSetIterator hrrs(r->rem_set());
2865 size_t card_index;
2866 while (hrrs.has_next(card_index)) {
2867 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2868 // The remembered set might contain references to already freed
2869 // regions. Filter out such entries to avoid failing card table
2870 // verification.
2871 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2872 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2873 *card_ptr = CardTableModRefBS::dirty_card_val();
2874 _dcq.enqueue(card_ptr);
2875 }
2876 }
2877 }
2878 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2879 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2880 hrrs.n_yielded(), r->rem_set()->occupied());
2881 r->rem_set()->clear_locked();
2882 }
2883 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2884 }
2885 _total_humongous++;
2886
2887 return false;
2888 }
2889
2890 size_t total_humongous() const { return _total_humongous; }
2891 size_t candidate_humongous() const { return _candidate_humongous; }
2892
2893 void flush_rem_set_entries() { _dcq.flush(); }
2894 };
2895
2896 void G1CollectedHeap::register_humongous_regions_with_cset() {
2897 if (!G1EagerReclaimHumongousObjects) {
2898 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2899 return;
2900 }
2901 double time = os::elapsed_counter();
2902
2903 // Collect reclaim candidate information and register candidates with cset.
2904 RegisterHumongousWithInCSetFastTestClosure cl;
2905 heap_region_iterate(&cl);
2906
2907 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2908 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2909 cl.total_humongous(),
2910 cl.candidate_humongous());
2911 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2912
2913 // Finally flush all remembered set entries to re-check into the global DCQS.
2914 cl.flush_rem_set_entries();
2915 }
2916
2917 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2918 public:
2919 bool doHeapRegion(HeapRegion* hr) {
2920 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2921 hr->verify_rem_set();
2922 }
2923 return false;
2924 }
2925 };
2926
2927 uint G1CollectedHeap::num_task_queues() const {
2928 return _task_queues->size();
2929 }
2930
2931 #if TASKQUEUE_STATS
2932 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2933 st->print_raw_cr("GC Task Stats");
2934 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2935 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2936 }
2937
2938 void G1CollectedHeap::print_taskqueue_stats() const {
2939 if (!log_is_enabled(Trace, gc, task, stats)) {
2940 return;
2941 }
2942 Log(gc, task, stats) log;
2943 ResourceMark rm;
2944 outputStream* st = log.trace_stream();
2945
2946 print_taskqueue_stats_hdr(st);
2947
2948 TaskQueueStats totals;
2949 const uint n = num_task_queues();
2950 for (uint i = 0; i < n; ++i) {
2951 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2952 totals += task_queue(i)->stats;
2953 }
2954 st->print_raw("tot "); totals.print(st); st->cr();
2955
2956 DEBUG_ONLY(totals.verify());
2957 }
2958
2959 void G1CollectedHeap::reset_taskqueue_stats() {
2960 const uint n = num_task_queues();
2961 for (uint i = 0; i < n; ++i) {
2962 task_queue(i)->stats.reset();
2963 }
2964 }
2965 #endif // TASKQUEUE_STATS
2966
2967 void G1CollectedHeap::wait_for_root_region_scanning() {
2968 double scan_wait_start = os::elapsedTime();
2969 // We have to wait until the CM threads finish scanning the
2970 // root regions as it's the only way to ensure that all the
2971 // objects on them have been correctly scanned before we start
2972 // moving them during the GC.
2973 bool waited = _cm->root_regions()->wait_until_scan_finished();
2974 double wait_time_ms = 0.0;
2975 if (waited) {
2976 double scan_wait_end = os::elapsedTime();
2977 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2978 }
2979 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2980 }
2981
2982 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2983 public:
2984 virtual bool doHeapRegion(HeapRegion* r) {
2985 G1CollectedHeap::heap()->hr_printer()->cset(r);
2986 return false;
2987 }
2988 };
2989
2990 bool
2991 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2992 assert_at_safepoint(true /* should_be_vm_thread */);
2993 guarantee(!is_gc_active(), "collection is not reentrant");
2994
2995 if (GCLocker::check_active_before_gc()) {
2996 return false;
2997 }
2998
2999 _gc_timer_stw->register_gc_start();
3000
3001 GCIdMark gc_id_mark;
3002 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3003
3004 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3005 ResourceMark rm;
3006
3007 g1_policy()->note_gc_start();
3008
3009 wait_for_root_region_scanning();
3010
3011 print_heap_before_gc();
3012 print_heap_regions();
3013 trace_heap_before_gc(_gc_tracer_stw);
3014
3015 _verifier->verify_region_sets_optional();
3016 _verifier->verify_dirty_young_regions();
3017
3018 // We should not be doing initial mark unless the conc mark thread is running
3019 if (!_cmThread->should_terminate()) {
3020 // This call will decide whether this pause is an initial-mark
3021 // pause. If it is, during_initial_mark_pause() will return true
3022 // for the duration of this pause.
3023 g1_policy()->decide_on_conc_mark_initiation();
3024 }
3025
3026 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3027 assert(!collector_state()->during_initial_mark_pause() ||
3028 collector_state()->gcs_are_young(), "sanity");
3029
3030 // We also do not allow mixed GCs during marking.
3031 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3032
3033 // Record whether this pause is an initial mark. When the current
3034 // thread has completed its logging output and it's safe to signal
3035 // the CM thread, the flag's value in the policy has been reset.
3036 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3037
3038 // Inner scope for scope based logging, timers, and stats collection
3039 {
3040 EvacuationInfo evacuation_info;
3041
3042 if (collector_state()->during_initial_mark_pause()) {
3043 // We are about to start a marking cycle, so we increment the
3044 // full collection counter.
3045 increment_old_marking_cycles_started();
3046 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3047 }
3048
3049 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3050
3051 GCTraceCPUTime tcpu;
3052
3053 FormatBuffer<> gc_string("Pause ");
3054 if (collector_state()->during_initial_mark_pause()) {
3055 gc_string.append("Initial Mark");
3056 } else if (collector_state()->gcs_are_young()) {
3057 gc_string.append("Young");
3058 } else {
3059 gc_string.append("Mixed");
3060 }
3061 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3062
3063 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3064 workers()->active_workers(),
3065 Threads::number_of_non_daemon_threads());
3066 workers()->set_active_workers(active_workers);
3067
3068 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3069 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3070
3071 // If the secondary_free_list is not empty, append it to the
3072 // free_list. No need to wait for the cleanup operation to finish;
3073 // the region allocation code will check the secondary_free_list
3074 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3075 // set, skip this step so that the region allocation code has to
3076 // get entries from the secondary_free_list.
3077 if (!G1StressConcRegionFreeing) {
3078 append_secondary_free_list_if_not_empty_with_lock();
3079 }
3080
3081 G1HeapTransition heap_transition(this);
3082 size_t heap_used_bytes_before_gc = used();
3083
3084 // Don't dynamically change the number of GC threads this early. A value of
3085 // 0 is used to indicate serial work. When parallel work is done,
3086 // it will be set.
3087
3088 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3089 IsGCActiveMark x;
3090
3091 gc_prologue(false);
3092 increment_total_collections(false /* full gc */);
3093 increment_gc_time_stamp();
3094
3095 if (VerifyRememberedSets) {
3096 log_info(gc, verify)("[Verifying RemSets before GC]");
3097 VerifyRegionRemSetClosure v_cl;
3098 heap_region_iterate(&v_cl);
3099 }
3100
3101 _verifier->verify_before_gc();
3102
3103 _verifier->check_bitmaps("GC Start");
3104
3105 #if defined(COMPILER2) || INCLUDE_JVMCI
3106 DerivedPointerTable::clear();
3107 #endif
3108
3109 // Please see comment in g1CollectedHeap.hpp and
3110 // G1CollectedHeap::ref_processing_init() to see how
3111 // reference processing currently works in G1.
3112
3113 // Enable discovery in the STW reference processor
3114 if (g1_policy()->should_process_references()) {
3115 ref_processor_stw()->enable_discovery();
3116 } else {
3117 ref_processor_stw()->disable_discovery();
3118 }
3119
3120 {
3121 // We want to temporarily turn off discovery by the
3122 // CM ref processor, if necessary, and turn it back on
3123 // on again later if we do. Using a scoped
3124 // NoRefDiscovery object will do this.
3125 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3126
3127 // Forget the current alloc region (we might even choose it to be part
3128 // of the collection set!).
3129 _allocator->release_mutator_alloc_region();
3130
3131 // This timing is only used by the ergonomics to handle our pause target.
3132 // It is unclear why this should not include the full pause. We will
3133 // investigate this in CR 7178365.
3134 //
3135 // Preserving the old comment here if that helps the investigation:
3136 //
3137 // The elapsed time induced by the start time below deliberately elides
3138 // the possible verification above.
3139 double sample_start_time_sec = os::elapsedTime();
3140
3141 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3142
3143 if (collector_state()->during_initial_mark_pause()) {
3144 concurrent_mark()->checkpointRootsInitialPre();
3145 }
3146
3147 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3148
3149 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3150
3151 // Make sure the remembered sets are up to date. This needs to be
3152 // done before register_humongous_regions_with_cset(), because the
3153 // remembered sets are used there to choose eager reclaim candidates.
3154 // If the remembered sets are not up to date we might miss some
3155 // entries that need to be handled.
3156 g1_rem_set()->cleanupHRRS();
3157
3158 register_humongous_regions_with_cset();
3159
3160 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3161
3162 _cm->note_start_of_gc();
3163 // We call this after finalize_cset() to
3164 // ensure that the CSet has been finalized.
3165 _cm->verify_no_cset_oops();
3166
3167 if (_hr_printer.is_active()) {
3168 G1PrintCollectionSetClosure cl;
3169 _collection_set.iterate(&cl);
3170 }
3171
3172 // Initialize the GC alloc regions.
3173 _allocator->init_gc_alloc_regions(evacuation_info);
3174
3175 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3176 pre_evacuate_collection_set();
3177
3178 // Actually do the work...
3179 evacuate_collection_set(evacuation_info, &per_thread_states);
3180
3181 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3182
3183 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3184 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3185
3186 eagerly_reclaim_humongous_regions();
3187
3188 record_obj_copy_mem_stats();
3189 _survivor_evac_stats.adjust_desired_plab_sz();
3190 _old_evac_stats.adjust_desired_plab_sz();
3191
3192 // Start a new incremental collection set for the next pause.
3193 collection_set()->start_incremental_building();
3194
3195 clear_cset_fast_test();
3196
3197 guarantee(_eden.length() == 0, "eden should have been cleared");
3198 g1_policy()->transfer_survivors_to_cset(survivor());
3199
3200 if (evacuation_failed()) {
3201 set_used(recalculate_used());
3202 if (_archive_allocator != NULL) {
3203 _archive_allocator->clear_used();
3204 }
3205 for (uint i = 0; i < ParallelGCThreads; i++) {
3206 if (_evacuation_failed_info_array[i].has_failed()) {
3207 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3208 }
3209 }
3210 } else {
3211 // The "used" of the the collection set have already been subtracted
3212 // when they were freed. Add in the bytes evacuated.
3213 increase_used(g1_policy()->bytes_copied_during_gc());
3214 }
3215
3216 if (collector_state()->during_initial_mark_pause()) {
3217 // We have to do this before we notify the CM threads that
3218 // they can start working to make sure that all the
3219 // appropriate initialization is done on the CM object.
3220 concurrent_mark()->checkpointRootsInitialPost();
3221 collector_state()->set_mark_in_progress(true);
3222 // Note that we don't actually trigger the CM thread at
3223 // this point. We do that later when we're sure that
3224 // the current thread has completed its logging output.
3225 }
3226
3227 allocate_dummy_regions();
3228
3229 _allocator->init_mutator_alloc_region();
3230
3231 {
3232 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3233 if (expand_bytes > 0) {
3234 size_t bytes_before = capacity();
3235 // No need for an ergo logging here,
3236 // expansion_amount() does this when it returns a value > 0.
3237 double expand_ms;
3238 if (!expand(expand_bytes, &expand_ms)) {
3239 // We failed to expand the heap. Cannot do anything about it.
3240 }
3241 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3242 }
3243 }
3244
3245 // We redo the verification but now wrt to the new CSet which
3246 // has just got initialized after the previous CSet was freed.
3247 _cm->verify_no_cset_oops();
3248 _cm->note_end_of_gc();
3249
3250 // This timing is only used by the ergonomics to handle our pause target.
3251 // It is unclear why this should not include the full pause. We will
3252 // investigate this in CR 7178365.
3253 double sample_end_time_sec = os::elapsedTime();
3254 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3255 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3256 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3257
3258 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3259 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3260
3261 MemoryService::track_memory_usage();
3262
3263 // In prepare_for_verify() below we'll need to scan the deferred
3264 // update buffers to bring the RSets up-to-date if
3265 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3266 // the update buffers we'll probably need to scan cards on the
3267 // regions we just allocated to (i.e., the GC alloc
3268 // regions). However, during the last GC we called
3269 // set_saved_mark() on all the GC alloc regions, so card
3270 // scanning might skip the [saved_mark_word()...top()] area of
3271 // those regions (i.e., the area we allocated objects into
3272 // during the last GC). But it shouldn't. Given that
3273 // saved_mark_word() is conditional on whether the GC time stamp
3274 // on the region is current or not, by incrementing the GC time
3275 // stamp here we invalidate all the GC time stamps on all the
3276 // regions and saved_mark_word() will simply return top() for
3277 // all the regions. This is a nicer way of ensuring this rather
3278 // than iterating over the regions and fixing them. In fact, the
3279 // GC time stamp increment here also ensures that
3280 // saved_mark_word() will return top() between pauses, i.e.,
3281 // during concurrent refinement. So we don't need the
3282 // is_gc_active() check to decided which top to use when
3283 // scanning cards (see CR 7039627).
3284 increment_gc_time_stamp();
3285
3286 if (VerifyRememberedSets) {
3287 log_info(gc, verify)("[Verifying RemSets after GC]");
3288 VerifyRegionRemSetClosure v_cl;
3289 heap_region_iterate(&v_cl);
3290 }
3291
3292 _verifier->verify_after_gc();
3293 _verifier->check_bitmaps("GC End");
3294
3295 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3296 ref_processor_stw()->verify_no_references_recorded();
3297
3298 // CM reference discovery will be re-enabled if necessary.
3299 }
3300
3301 #ifdef TRACESPINNING
3302 ParallelTaskTerminator::print_termination_counts();
3303 #endif
3304
3305 gc_epilogue(false);
3306 }
3307
3308 // Print the remainder of the GC log output.
3309 if (evacuation_failed()) {
3310 log_info(gc)("To-space exhausted");
3311 }
3312
3313 g1_policy()->print_phases();
3314 heap_transition.print();
3315
3316 // It is not yet to safe to tell the concurrent mark to
3317 // start as we have some optional output below. We don't want the
3318 // output from the concurrent mark thread interfering with this
3319 // logging output either.
3320
3321 _hrm.verify_optional();
3322 _verifier->verify_region_sets_optional();
3323
3324 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3325 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3326
3327 print_heap_after_gc();
3328 print_heap_regions();
3329 trace_heap_after_gc(_gc_tracer_stw);
3330
3331 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3332 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3333 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3334 // before any GC notifications are raised.
3335 g1mm()->update_sizes();
3336
3337 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3338 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3339 _gc_timer_stw->register_gc_end();
3340 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3341 }
3342 // It should now be safe to tell the concurrent mark thread to start
3343 // without its logging output interfering with the logging output
3344 // that came from the pause.
3345
3346 if (should_start_conc_mark) {
3347 // CAUTION: after the doConcurrentMark() call below,
3348 // the concurrent marking thread(s) could be running
3349 // concurrently with us. Make sure that anything after
3350 // this point does not assume that we are the only GC thread
3351 // running. Note: of course, the actual marking work will
3352 // not start until the safepoint itself is released in
3353 // SuspendibleThreadSet::desynchronize().
3354 doConcurrentMark();
3355 }
3356
3357 return true;
3358 }
3359
3360 void G1CollectedHeap::remove_self_forwarding_pointers() {
3361 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3362 workers()->run_task(&rsfp_task);
3363 }
3364
3365 void G1CollectedHeap::restore_after_evac_failure() {
3366 double remove_self_forwards_start = os::elapsedTime();
3367
3368 remove_self_forwarding_pointers();
3369 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3370 _preserved_marks_set.restore(&task_executor);
3371
3372 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3373 }
3374
3375 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3376 if (!_evacuation_failed) {
3377 _evacuation_failed = true;
3378 }
3379
3380 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3381 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3382 }
3383
3384 bool G1ParEvacuateFollowersClosure::offer_termination() {
3385 G1ParScanThreadState* const pss = par_scan_state();
3386 start_term_time();
3387 const bool res = terminator()->offer_termination();
3388 end_term_time();
3389 return res;
3390 }
3391
3392 void G1ParEvacuateFollowersClosure::do_void() {
3393 G1ParScanThreadState* const pss = par_scan_state();
3394 pss->trim_queue();
3395 do {
3396 pss->steal_and_trim_queue(queues());
3397 } while (!offer_termination());
3398 }
3399
3400 class G1ParTask : public AbstractGangTask {
3401 protected:
3402 G1CollectedHeap* _g1h;
3403 G1ParScanThreadStateSet* _pss;
3404 RefToScanQueueSet* _queues;
3405 G1RootProcessor* _root_processor;
3406 ParallelTaskTerminator _terminator;
3407 uint _n_workers;
3408
3409 public:
3410 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3411 : AbstractGangTask("G1 collection"),
3412 _g1h(g1h),
3413 _pss(per_thread_states),
3414 _queues(task_queues),
3415 _root_processor(root_processor),
3416 _terminator(n_workers, _queues),
3417 _n_workers(n_workers)
3418 {}
3419
3420 void work(uint worker_id) {
3421 if (worker_id >= _n_workers) return; // no work needed this round
3422
3423 double start_sec = os::elapsedTime();
3424 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3425
3426 {
3427 ResourceMark rm;
3428 HandleMark hm;
3429
3430 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3431
3432 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3433 pss->set_ref_processor(rp);
3434
3435 double start_strong_roots_sec = os::elapsedTime();
3436
3437 _root_processor->evacuate_roots(pss->closures(), worker_id);
3438
3439 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3440
3441 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3442 // treating the nmethods visited to act as roots for concurrent marking.
3443 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3444 // objects copied by the current evacuation.
3445 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3446 pss->closures()->weak_codeblobs(),
3447 worker_id);
3448
3449 _pss->add_cards_scanned(worker_id, cards_scanned);
3450
3451 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3452
3453 double term_sec = 0.0;
3454 size_t evac_term_attempts = 0;
3455 {
3456 double start = os::elapsedTime();
3457 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3458 evac.do_void();
3459
3460 evac_term_attempts = evac.term_attempts();
3461 term_sec = evac.term_time();
3462 double elapsed_sec = os::elapsedTime() - start;
3463 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3464 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3465 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3466 }
3467
3468 assert(pss->queue_is_empty(), "should be empty");
3469
3470 if (log_is_enabled(Debug, gc, task, stats)) {
3471 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3472 size_t lab_waste;
3473 size_t lab_undo_waste;
3474 pss->waste(lab_waste, lab_undo_waste);
3475 _g1h->print_termination_stats(worker_id,
3476 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3477 strong_roots_sec * 1000.0, /* strong roots time */
3478 term_sec * 1000.0, /* evac term time */
3479 evac_term_attempts, /* evac term attempts */
3480 lab_waste, /* alloc buffer waste */
3481 lab_undo_waste /* undo waste */
3482 );
3483 }
3484
3485 // Close the inner scope so that the ResourceMark and HandleMark
3486 // destructors are executed here and are included as part of the
3487 // "GC Worker Time".
3488 }
3489 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3490 }
3491 };
3492
3493 void G1CollectedHeap::print_termination_stats_hdr() {
3494 log_debug(gc, task, stats)("GC Termination Stats");
3495 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3496 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3497 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3498 }
3499
3500 void G1CollectedHeap::print_termination_stats(uint worker_id,
3501 double elapsed_ms,
3502 double strong_roots_ms,
3503 double term_ms,
3504 size_t term_attempts,
3505 size_t alloc_buffer_waste,
3506 size_t undo_waste) const {
3507 log_debug(gc, task, stats)
3508 ("%3d %9.2f %9.2f %6.2f "
3509 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3510 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3511 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3512 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3513 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3514 alloc_buffer_waste * HeapWordSize / K,
3515 undo_waste * HeapWordSize / K);
3516 }
3517
3518 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3519 private:
3520 BoolObjectClosure* _is_alive;
3521 int _initial_string_table_size;
3522 int _initial_symbol_table_size;
3523
3524 bool _process_strings;
3525 int _strings_processed;
3526 int _strings_removed;
3527
3528 bool _process_symbols;
3529 int _symbols_processed;
3530 int _symbols_removed;
3531
3532 public:
3533 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3534 AbstractGangTask("String/Symbol Unlinking"),
3535 _is_alive(is_alive),
3536 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3537 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3538
3539 _initial_string_table_size = StringTable::the_table()->table_size();
3540 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3541 if (process_strings) {
3542 StringTable::clear_parallel_claimed_index();
3543 }
3544 if (process_symbols) {
3545 SymbolTable::clear_parallel_claimed_index();
3546 }
3547 }
3548
3549 ~G1StringSymbolTableUnlinkTask() {
3550 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3551 "claim value %d after unlink less than initial string table size %d",
3552 StringTable::parallel_claimed_index(), _initial_string_table_size);
3553 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3554 "claim value %d after unlink less than initial symbol table size %d",
3555 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3556
3557 log_info(gc, stringtable)(
3558 "Cleaned string and symbol table, "
3559 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3560 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3561 strings_processed(), strings_removed(),
3562 symbols_processed(), symbols_removed());
3563 }
3564
3565 void work(uint worker_id) {
3566 int strings_processed = 0;
3567 int strings_removed = 0;
3568 int symbols_processed = 0;
3569 int symbols_removed = 0;
3570 if (_process_strings) {
3571 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3572 Atomic::add(strings_processed, &_strings_processed);
3573 Atomic::add(strings_removed, &_strings_removed);
3574 }
3575 if (_process_symbols) {
3576 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3577 Atomic::add(symbols_processed, &_symbols_processed);
3578 Atomic::add(symbols_removed, &_symbols_removed);
3579 }
3580 }
3581
3582 size_t strings_processed() const { return (size_t)_strings_processed; }
3583 size_t strings_removed() const { return (size_t)_strings_removed; }
3584
3585 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3586 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3587 };
3588
3589 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3590 private:
3591 static Monitor* _lock;
3592
3593 BoolObjectClosure* const _is_alive;
3594 const bool _unloading_occurred;
3595 const uint _num_workers;
3596
3597 // Variables used to claim nmethods.
3598 CompiledMethod* _first_nmethod;
3599 volatile CompiledMethod* _claimed_nmethod;
3600
3601 // The list of nmethods that need to be processed by the second pass.
3602 volatile CompiledMethod* _postponed_list;
3603 volatile uint _num_entered_barrier;
3604
3605 public:
3606 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3607 _is_alive(is_alive),
3608 _unloading_occurred(unloading_occurred),
3609 _num_workers(num_workers),
3610 _first_nmethod(NULL),
3611 _claimed_nmethod(NULL),
3612 _postponed_list(NULL),
3613 _num_entered_barrier(0)
3614 {
3615 CompiledMethod::increase_unloading_clock();
3616 // Get first alive nmethod
3617 CompiledMethodIterator iter = CompiledMethodIterator();
3618 if(iter.next_alive()) {
3619 _first_nmethod = iter.method();
3620 }
3621 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3622 }
3623
3624 ~G1CodeCacheUnloadingTask() {
3625 CodeCache::verify_clean_inline_caches();
3626
3627 CodeCache::set_needs_cache_clean(false);
3628 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3629
3630 CodeCache::verify_icholder_relocations();
3631 }
3632
3633 private:
3634 void add_to_postponed_list(CompiledMethod* nm) {
3635 CompiledMethod* old;
3636 do {
3637 old = (CompiledMethod*)_postponed_list;
3638 nm->set_unloading_next(old);
3639 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3640 }
3641
3642 void clean_nmethod(CompiledMethod* nm) {
3643 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3644
3645 if (postponed) {
3646 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3647 add_to_postponed_list(nm);
3648 }
3649
3650 // Mark that this thread has been cleaned/unloaded.
3651 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3652 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3653 }
3654
3655 void clean_nmethod_postponed(CompiledMethod* nm) {
3656 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3657 }
3658
3659 static const int MaxClaimNmethods = 16;
3660
3661 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3662 CompiledMethod* first;
3663 CompiledMethodIterator last;
3664
3665 do {
3666 *num_claimed_nmethods = 0;
3667
3668 first = (CompiledMethod*)_claimed_nmethod;
3669 last = CompiledMethodIterator(first);
3670
3671 if (first != NULL) {
3672
3673 for (int i = 0; i < MaxClaimNmethods; i++) {
3674 if (!last.next_alive()) {
3675 break;
3676 }
3677 claimed_nmethods[i] = last.method();
3678 (*num_claimed_nmethods)++;
3679 }
3680 }
3681
3682 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3683 }
3684
3685 CompiledMethod* claim_postponed_nmethod() {
3686 CompiledMethod* claim;
3687 CompiledMethod* next;
3688
3689 do {
3690 claim = (CompiledMethod*)_postponed_list;
3691 if (claim == NULL) {
3692 return NULL;
3693 }
3694
3695 next = claim->unloading_next();
3696
3697 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3698
3699 return claim;
3700 }
3701
3702 public:
3703 // Mark that we're done with the first pass of nmethod cleaning.
3704 void barrier_mark(uint worker_id) {
3705 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3706 _num_entered_barrier++;
3707 if (_num_entered_barrier == _num_workers) {
3708 ml.notify_all();
3709 }
3710 }
3711
3712 // See if we have to wait for the other workers to
3713 // finish their first-pass nmethod cleaning work.
3714 void barrier_wait(uint worker_id) {
3715 if (_num_entered_barrier < _num_workers) {
3716 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3717 while (_num_entered_barrier < _num_workers) {
3718 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3719 }
3720 }
3721 }
3722
3723 // Cleaning and unloading of nmethods. Some work has to be postponed
3724 // to the second pass, when we know which nmethods survive.
3725 void work_first_pass(uint worker_id) {
3726 // The first nmethods is claimed by the first worker.
3727 if (worker_id == 0 && _first_nmethod != NULL) {
3728 clean_nmethod(_first_nmethod);
3729 _first_nmethod = NULL;
3730 }
3731
3732 int num_claimed_nmethods;
3733 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3734
3735 while (true) {
3736 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3737
3738 if (num_claimed_nmethods == 0) {
3739 break;
3740 }
3741
3742 for (int i = 0; i < num_claimed_nmethods; i++) {
3743 clean_nmethod(claimed_nmethods[i]);
3744 }
3745 }
3746 }
3747
3748 void work_second_pass(uint worker_id) {
3749 CompiledMethod* nm;
3750 // Take care of postponed nmethods.
3751 while ((nm = claim_postponed_nmethod()) != NULL) {
3752 clean_nmethod_postponed(nm);
3753 }
3754 }
3755 };
3756
3757 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3758
3759 class G1KlassCleaningTask : public StackObj {
3760 BoolObjectClosure* _is_alive;
3761 volatile jint _clean_klass_tree_claimed;
3762 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3763
3764 public:
3765 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3766 _is_alive(is_alive),
3767 _clean_klass_tree_claimed(0),
3768 _klass_iterator() {
3769 }
3770
3771 private:
3772 bool claim_clean_klass_tree_task() {
3773 if (_clean_klass_tree_claimed) {
3774 return false;
3775 }
3776
3777 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3778 }
3779
3780 InstanceKlass* claim_next_klass() {
3781 Klass* klass;
3782 do {
3783 klass =_klass_iterator.next_klass();
3784 } while (klass != NULL && !klass->is_instance_klass());
3785
3786 // this can be null so don't call InstanceKlass::cast
3787 return static_cast<InstanceKlass*>(klass);
3788 }
3789
3790 public:
3791
3792 void clean_klass(InstanceKlass* ik) {
3793 ik->clean_weak_instanceklass_links(_is_alive);
3794 }
3795
3796 void work() {
3797 ResourceMark rm;
3798
3799 // One worker will clean the subklass/sibling klass tree.
3800 if (claim_clean_klass_tree_task()) {
3801 Klass::clean_subklass_tree(_is_alive);
3802 }
3803
3804 // All workers will help cleaning the classes,
3805 InstanceKlass* klass;
3806 while ((klass = claim_next_klass()) != NULL) {
3807 clean_klass(klass);
3808 }
3809 }
3810 };
3811
3812 // To minimize the remark pause times, the tasks below are done in parallel.
3813 class G1ParallelCleaningTask : public AbstractGangTask {
3814 private:
3815 G1StringSymbolTableUnlinkTask _string_symbol_task;
3816 G1CodeCacheUnloadingTask _code_cache_task;
3817 G1KlassCleaningTask _klass_cleaning_task;
3818
3819 public:
3820 // The constructor is run in the VMThread.
3821 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
3822 AbstractGangTask("Parallel Cleaning"),
3823 _string_symbol_task(is_alive, process_strings, process_symbols),
3824 _code_cache_task(num_workers, is_alive, unloading_occurred),
3825 _klass_cleaning_task(is_alive) {
3826 }
3827
3828 // The parallel work done by all worker threads.
3829 void work(uint worker_id) {
3830 // Do first pass of code cache cleaning.
3831 _code_cache_task.work_first_pass(worker_id);
3832
3833 // Let the threads mark that the first pass is done.
3834 _code_cache_task.barrier_mark(worker_id);
3835
3836 // Clean the Strings and Symbols.
3837 _string_symbol_task.work(worker_id);
3838
3839 // Wait for all workers to finish the first code cache cleaning pass.
3840 _code_cache_task.barrier_wait(worker_id);
3841
3842 // Do the second code cache cleaning work, which realize on
3843 // the liveness information gathered during the first pass.
3844 _code_cache_task.work_second_pass(worker_id);
3845
3846 // Clean all klasses that were not unloaded.
3847 _klass_cleaning_task.work();
3848 }
3849 };
3850
3851
3852 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
3853 bool process_strings,
3854 bool process_symbols,
3855 bool class_unloading_occurred) {
3856 uint n_workers = workers()->active_workers();
3857
3858 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
3859 n_workers, class_unloading_occurred);
3860 workers()->run_task(&g1_unlink_task);
3861 }
3862
3863 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
3864 bool process_strings, bool process_symbols) {
3865 { // Timing scope
3866 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
3867 workers()->run_task(&g1_unlink_task);
3868 }
3869 }
3870
3871 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3872 private:
3873 DirtyCardQueueSet* _queue;
3874 G1CollectedHeap* _g1h;
3875 public:
3876 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3877 _queue(queue), _g1h(g1h) { }
3878
3879 virtual void work(uint worker_id) {
3880 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3881 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3882
3883 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3884 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3885
3886 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3887 }
3888 };
3889
3890 void G1CollectedHeap::redirty_logged_cards() {
3891 double redirty_logged_cards_start = os::elapsedTime();
3892
3893 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3894 dirty_card_queue_set().reset_for_par_iteration();
3895 workers()->run_task(&redirty_task);
3896
3897 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3898 dcq.merge_bufferlists(&dirty_card_queue_set());
3899 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3900
3901 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3902 }
3903
3904 // Weak Reference Processing support
3905
3906 // An always "is_alive" closure that is used to preserve referents.
3907 // If the object is non-null then it's alive. Used in the preservation
3908 // of referent objects that are pointed to by reference objects
3909 // discovered by the CM ref processor.
3910 class G1AlwaysAliveClosure: public BoolObjectClosure {
3911 G1CollectedHeap* _g1;
3912 public:
3913 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3914 bool do_object_b(oop p) {
3915 if (p != NULL) {
3916 return true;
3917 }
3918 return false;
3919 }
3920 };
3921
3922 bool G1STWIsAliveClosure::do_object_b(oop p) {
3923 // An object is reachable if it is outside the collection set,
3924 // or is inside and copied.
3925 return !_g1->is_in_cset(p) || p->is_forwarded();
3926 }
3927
3928 // Non Copying Keep Alive closure
3929 class G1KeepAliveClosure: public OopClosure {
3930 G1CollectedHeap* _g1;
3931 public:
3932 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3933 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3934 void do_oop(oop* p) {
3935 oop obj = *p;
3936 assert(obj != NULL, "the caller should have filtered out NULL values");
3937
3938 const InCSetState cset_state = _g1->in_cset_state(obj);
3939 if (!cset_state.is_in_cset_or_humongous()) {
3940 return;
3941 }
3942 if (cset_state.is_in_cset()) {
3943 assert( obj->is_forwarded(), "invariant" );
3944 *p = obj->forwardee();
3945 } else {
3946 assert(!obj->is_forwarded(), "invariant" );
3947 assert(cset_state.is_humongous(),
3948 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3949 _g1->set_humongous_is_live(obj);
3950 }
3951 }
3952 };
3953
3954 // Copying Keep Alive closure - can be called from both
3955 // serial and parallel code as long as different worker
3956 // threads utilize different G1ParScanThreadState instances
3957 // and different queues.
3958
3959 class G1CopyingKeepAliveClosure: public OopClosure {
3960 G1CollectedHeap* _g1h;
3961 OopClosure* _copy_non_heap_obj_cl;
3962 G1ParScanThreadState* _par_scan_state;
3963
3964 public:
3965 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3966 OopClosure* non_heap_obj_cl,
3967 G1ParScanThreadState* pss):
3968 _g1h(g1h),
3969 _copy_non_heap_obj_cl(non_heap_obj_cl),
3970 _par_scan_state(pss)
3971 {}
3972
3973 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3974 virtual void do_oop( oop* p) { do_oop_work(p); }
3975
3976 template <class T> void do_oop_work(T* p) {
3977 oop obj = oopDesc::load_decode_heap_oop(p);
3978
3979 if (_g1h->is_in_cset_or_humongous(obj)) {
3980 // If the referent object has been forwarded (either copied
3981 // to a new location or to itself in the event of an
3982 // evacuation failure) then we need to update the reference
3983 // field and, if both reference and referent are in the G1
3984 // heap, update the RSet for the referent.
3985 //
3986 // If the referent has not been forwarded then we have to keep
3987 // it alive by policy. Therefore we have copy the referent.
3988 //
3989 // If the reference field is in the G1 heap then we can push
3990 // on the PSS queue. When the queue is drained (after each
3991 // phase of reference processing) the object and it's followers
3992 // will be copied, the reference field set to point to the
3993 // new location, and the RSet updated. Otherwise we need to
3994 // use the the non-heap or metadata closures directly to copy
3995 // the referent object and update the pointer, while avoiding
3996 // updating the RSet.
3997
3998 if (_g1h->is_in_g1_reserved(p)) {
3999 _par_scan_state->push_on_queue(p);
4000 } else {
4001 assert(!Metaspace::contains((const void*)p),
4002 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4003 _copy_non_heap_obj_cl->do_oop(p);
4004 }
4005 }
4006 }
4007 };
4008
4009 // Serial drain queue closure. Called as the 'complete_gc'
4010 // closure for each discovered list in some of the
4011 // reference processing phases.
4012
4013 class G1STWDrainQueueClosure: public VoidClosure {
4014 protected:
4015 G1CollectedHeap* _g1h;
4016 G1ParScanThreadState* _par_scan_state;
4017
4018 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4019
4020 public:
4021 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4022 _g1h(g1h),
4023 _par_scan_state(pss)
4024 { }
4025
4026 void do_void() {
4027 G1ParScanThreadState* const pss = par_scan_state();
4028 pss->trim_queue();
4029 }
4030 };
4031
4032 // Parallel Reference Processing closures
4033
4034 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4035 // processing during G1 evacuation pauses.
4036
4037 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4038 private:
4039 G1CollectedHeap* _g1h;
4040 G1ParScanThreadStateSet* _pss;
4041 RefToScanQueueSet* _queues;
4042 WorkGang* _workers;
4043 uint _active_workers;
4044
4045 public:
4046 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4047 G1ParScanThreadStateSet* per_thread_states,
4048 WorkGang* workers,
4049 RefToScanQueueSet *task_queues,
4050 uint n_workers) :
4051 _g1h(g1h),
4052 _pss(per_thread_states),
4053 _queues(task_queues),
4054 _workers(workers),
4055 _active_workers(n_workers)
4056 {
4057 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4058 }
4059
4060 // Executes the given task using concurrent marking worker threads.
4061 virtual void execute(ProcessTask& task);
4062 virtual void execute(EnqueueTask& task);
4063 };
4064
4065 // Gang task for possibly parallel reference processing
4066
4067 class G1STWRefProcTaskProxy: public AbstractGangTask {
4068 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4069 ProcessTask& _proc_task;
4070 G1CollectedHeap* _g1h;
4071 G1ParScanThreadStateSet* _pss;
4072 RefToScanQueueSet* _task_queues;
4073 ParallelTaskTerminator* _terminator;
4074
4075 public:
4076 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4077 G1CollectedHeap* g1h,
4078 G1ParScanThreadStateSet* per_thread_states,
4079 RefToScanQueueSet *task_queues,
4080 ParallelTaskTerminator* terminator) :
4081 AbstractGangTask("Process reference objects in parallel"),
4082 _proc_task(proc_task),
4083 _g1h(g1h),
4084 _pss(per_thread_states),
4085 _task_queues(task_queues),
4086 _terminator(terminator)
4087 {}
4088
4089 virtual void work(uint worker_id) {
4090 // The reference processing task executed by a single worker.
4091 ResourceMark rm;
4092 HandleMark hm;
4093
4094 G1STWIsAliveClosure is_alive(_g1h);
4095
4096 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4097 pss->set_ref_processor(NULL);
4098
4099 // Keep alive closure.
4100 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4101
4102 // Complete GC closure
4103 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4104
4105 // Call the reference processing task's work routine.
4106 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4107
4108 // Note we cannot assert that the refs array is empty here as not all
4109 // of the processing tasks (specifically phase2 - pp2_work) execute
4110 // the complete_gc closure (which ordinarily would drain the queue) so
4111 // the queue may not be empty.
4112 }
4113 };
4114
4115 // Driver routine for parallel reference processing.
4116 // Creates an instance of the ref processing gang
4117 // task and has the worker threads execute it.
4118 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4119 assert(_workers != NULL, "Need parallel worker threads.");
4120
4121 ParallelTaskTerminator terminator(_active_workers, _queues);
4122 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4123
4124 _workers->run_task(&proc_task_proxy);
4125 }
4126
4127 // Gang task for parallel reference enqueueing.
4128
4129 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4130 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4131 EnqueueTask& _enq_task;
4132
4133 public:
4134 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4135 AbstractGangTask("Enqueue reference objects in parallel"),
4136 _enq_task(enq_task)
4137 { }
4138
4139 virtual void work(uint worker_id) {
4140 _enq_task.work(worker_id);
4141 }
4142 };
4143
4144 // Driver routine for parallel reference enqueueing.
4145 // Creates an instance of the ref enqueueing gang
4146 // task and has the worker threads execute it.
4147
4148 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4149 assert(_workers != NULL, "Need parallel worker threads.");
4150
4151 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4152
4153 _workers->run_task(&enq_task_proxy);
4154 }
4155
4156 // End of weak reference support closures
4157
4158 // Abstract task used to preserve (i.e. copy) any referent objects
4159 // that are in the collection set and are pointed to by reference
4160 // objects discovered by the CM ref processor.
4161
4162 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4163 protected:
4164 G1CollectedHeap* _g1h;
4165 G1ParScanThreadStateSet* _pss;
4166 RefToScanQueueSet* _queues;
4167 ParallelTaskTerminator _terminator;
4168 uint _n_workers;
4169
4170 public:
4171 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4172 AbstractGangTask("ParPreserveCMReferents"),
4173 _g1h(g1h),
4174 _pss(per_thread_states),
4175 _queues(task_queues),
4176 _terminator(workers, _queues),
4177 _n_workers(workers)
4178 {
4179 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4180 }
4181
4182 void work(uint worker_id) {
4183 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4184
4185 ResourceMark rm;
4186 HandleMark hm;
4187
4188 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4189 pss->set_ref_processor(NULL);
4190 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4191
4192 // Is alive closure
4193 G1AlwaysAliveClosure always_alive(_g1h);
4194
4195 // Copying keep alive closure. Applied to referent objects that need
4196 // to be copied.
4197 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4198
4199 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4200
4201 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4202 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4203
4204 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4205 // So this must be true - but assert just in case someone decides to
4206 // change the worker ids.
4207 assert(worker_id < limit, "sanity");
4208 assert(!rp->discovery_is_atomic(), "check this code");
4209
4210 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4211 for (uint idx = worker_id; idx < limit; idx += stride) {
4212 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4213
4214 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4215 while (iter.has_next()) {
4216 // Since discovery is not atomic for the CM ref processor, we
4217 // can see some null referent objects.
4218 iter.load_ptrs(DEBUG_ONLY(true));
4219 oop ref = iter.obj();
4220
4221 // This will filter nulls.
4222 if (iter.is_referent_alive()) {
4223 iter.make_referent_alive();
4224 }
4225 iter.move_to_next();
4226 }
4227 }
4228
4229 // Drain the queue - which may cause stealing
4230 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4231 drain_queue.do_void();
4232 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4233 assert(pss->queue_is_empty(), "should be");
4234 }
4235 };
4236
4237 void G1CollectedHeap::process_weak_jni_handles() {
4238 double ref_proc_start = os::elapsedTime();
4239
4240 G1STWIsAliveClosure is_alive(this);
4241 G1KeepAliveClosure keep_alive(this);
4242 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4243
4244 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4245 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4246 }
4247
4248 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4249 // Any reference objects, in the collection set, that were 'discovered'
4250 // by the CM ref processor should have already been copied (either by
4251 // applying the external root copy closure to the discovered lists, or
4252 // by following an RSet entry).
4253 //
4254 // But some of the referents, that are in the collection set, that these
4255 // reference objects point to may not have been copied: the STW ref
4256 // processor would have seen that the reference object had already
4257 // been 'discovered' and would have skipped discovering the reference,
4258 // but would not have treated the reference object as a regular oop.
4259 // As a result the copy closure would not have been applied to the
4260 // referent object.
4261 //
4262 // We need to explicitly copy these referent objects - the references
4263 // will be processed at the end of remarking.
4264 //
4265 // We also need to do this copying before we process the reference
4266 // objects discovered by the STW ref processor in case one of these
4267 // referents points to another object which is also referenced by an
4268 // object discovered by the STW ref processor.
4269 double preserve_cm_referents_time = 0.0;
4270
4271 // To avoid spawning task when there is no work to do, check that
4272 // a concurrent cycle is active and that some references have been
4273 // discovered.
4274 if (concurrent_mark()->cmThread()->during_cycle() &&
4275 ref_processor_cm()->has_discovered_references()) {
4276 double preserve_cm_referents_start = os::elapsedTime();
4277 uint no_of_gc_workers = workers()->active_workers();
4278 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4279 per_thread_states,
4280 no_of_gc_workers,
4281 _task_queues);
4282 workers()->run_task(&keep_cm_referents);
4283 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4284 }
4285
4286 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4287 }
4288
4289 // Weak Reference processing during an evacuation pause (part 1).
4290 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4291 double ref_proc_start = os::elapsedTime();
4292
4293 ReferenceProcessor* rp = _ref_processor_stw;
4294 assert(rp->discovery_enabled(), "should have been enabled");
4295
4296 // Closure to test whether a referent is alive.
4297 G1STWIsAliveClosure is_alive(this);
4298
4299 // Even when parallel reference processing is enabled, the processing
4300 // of JNI refs is serial and performed serially by the current thread
4301 // rather than by a worker. The following PSS will be used for processing
4302 // JNI refs.
4303
4304 // Use only a single queue for this PSS.
4305 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4306 pss->set_ref_processor(NULL);
4307 assert(pss->queue_is_empty(), "pre-condition");
4308
4309 // Keep alive closure.
4310 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4311
4312 // Serial Complete GC closure
4313 G1STWDrainQueueClosure drain_queue(this, pss);
4314
4315 // Setup the soft refs policy...
4316 rp->setup_policy(false);
4317
4318 ReferenceProcessorStats stats;
4319 if (!rp->processing_is_mt()) {
4320 // Serial reference processing...
4321 stats = rp->process_discovered_references(&is_alive,
4322 &keep_alive,
4323 &drain_queue,
4324 NULL,
4325 _gc_timer_stw);
4326 } else {
4327 uint no_of_gc_workers = workers()->active_workers();
4328
4329 // Parallel reference processing
4330 assert(no_of_gc_workers <= rp->max_num_q(),
4331 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4332 no_of_gc_workers, rp->max_num_q());
4333
4334 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4335 stats = rp->process_discovered_references(&is_alive,
4336 &keep_alive,
4337 &drain_queue,
4338 &par_task_executor,
4339 _gc_timer_stw);
4340 }
4341
4342 _gc_tracer_stw->report_gc_reference_stats(stats);
4343
4344 // We have completed copying any necessary live referent objects.
4345 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4346
4347 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4348 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4349 }
4350
4351 // Weak Reference processing during an evacuation pause (part 2).
4352 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4353 double ref_enq_start = os::elapsedTime();
4354
4355 ReferenceProcessor* rp = _ref_processor_stw;
4356 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4357
4358 // Now enqueue any remaining on the discovered lists on to
4359 // the pending list.
4360 if (!rp->processing_is_mt()) {
4361 // Serial reference processing...
4362 rp->enqueue_discovered_references();
4363 } else {
4364 // Parallel reference enqueueing
4365
4366 uint n_workers = workers()->active_workers();
4367
4368 assert(n_workers <= rp->max_num_q(),
4369 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4370 n_workers, rp->max_num_q());
4371
4372 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4373 rp->enqueue_discovered_references(&par_task_executor);
4374 }
4375
4376 rp->verify_no_references_recorded();
4377 assert(!rp->discovery_enabled(), "should have been disabled");
4378
4379 // FIXME
4380 // CM's reference processing also cleans up the string and symbol tables.
4381 // Should we do that here also? We could, but it is a serial operation
4382 // and could significantly increase the pause time.
4383
4384 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4385 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4386 }
4387
4388 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4389 double merge_pss_time_start = os::elapsedTime();
4390 per_thread_states->flush();
4391 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4392 }
4393
4394 void G1CollectedHeap::pre_evacuate_collection_set() {
4395 _expand_heap_after_alloc_failure = true;
4396 _evacuation_failed = false;
4397
4398 // Disable the hot card cache.
4399 _hot_card_cache->reset_hot_cache_claimed_index();
4400 _hot_card_cache->set_use_cache(false);
4401
4402 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4403 _preserved_marks_set.assert_empty();
4404 }
4405
4406 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4407 // Should G1EvacuationFailureALot be in effect for this GC?
4408 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4409
4410 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4411 double start_par_time_sec = os::elapsedTime();
4412 double end_par_time_sec;
4413
4414 {
4415 const uint n_workers = workers()->active_workers();
4416 G1RootProcessor root_processor(this, n_workers);
4417 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4418 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4419 if (collector_state()->during_initial_mark_pause()) {
4420 ClassLoaderDataGraph::clear_claimed_marks();
4421 }
4422
4423 print_termination_stats_hdr();
4424
4425 workers()->run_task(&g1_par_task);
4426 end_par_time_sec = os::elapsedTime();
4427
4428 // Closing the inner scope will execute the destructor
4429 // for the G1RootProcessor object. We record the current
4430 // elapsed time before closing the scope so that time
4431 // taken for the destructor is NOT included in the
4432 // reported parallel time.
4433 }
4434
4435 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4436
4437 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4438 phase_times->record_par_time(par_time_ms);
4439
4440 double code_root_fixup_time_ms =
4441 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4442 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4443 }
4444
4445 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4446 // Process any discovered reference objects - we have
4447 // to do this _before_ we retire the GC alloc regions
4448 // as we may have to copy some 'reachable' referent
4449 // objects (and their reachable sub-graphs) that were
4450 // not copied during the pause.
4451 if (g1_policy()->should_process_references()) {
4452 preserve_cm_referents(per_thread_states);
4453 process_discovered_references(per_thread_states);
4454 } else {
4455 ref_processor_stw()->verify_no_references_recorded();
4456 process_weak_jni_handles();
4457 }
4458
4459 if (G1StringDedup::is_enabled()) {
4460 double fixup_start = os::elapsedTime();
4461
4462 G1STWIsAliveClosure is_alive(this);
4463 G1KeepAliveClosure keep_alive(this);
4464 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4465
4466 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4467 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4468 }
4469
4470 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4471
4472 if (evacuation_failed()) {
4473 restore_after_evac_failure();
4474
4475 // Reset the G1EvacuationFailureALot counters and flags
4476 // Note: the values are reset only when an actual
4477 // evacuation failure occurs.
4478 NOT_PRODUCT(reset_evacuation_should_fail();)
4479 }
4480
4481 _preserved_marks_set.assert_empty();
4482
4483 // Enqueue any remaining references remaining on the STW
4484 // reference processor's discovered lists. We need to do
4485 // this after the card table is cleaned (and verified) as
4486 // the act of enqueueing entries on to the pending list
4487 // will log these updates (and dirty their associated
4488 // cards). We need these updates logged to update any
4489 // RSets.
4490 if (g1_policy()->should_process_references()) {
4491 enqueue_discovered_references(per_thread_states);
4492 } else {
4493 g1_policy()->phase_times()->record_ref_enq_time(0);
4494 }
4495
4496 _allocator->release_gc_alloc_regions(evacuation_info);
4497
4498 merge_per_thread_state_info(per_thread_states);
4499
4500 // Reset and re-enable the hot card cache.
4501 // Note the counts for the cards in the regions in the
4502 // collection set are reset when the collection set is freed.
4503 _hot_card_cache->reset_hot_cache();
4504 _hot_card_cache->set_use_cache(true);
4505
4506 purge_code_root_memory();
4507
4508 redirty_logged_cards();
4509 #if defined(COMPILER2) || INCLUDE_JVMCI
4510 DerivedPointerTable::update_pointers();
4511 #endif
4512 }
4513
4514 void G1CollectedHeap::record_obj_copy_mem_stats() {
4515 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4516
4517 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4518 create_g1_evac_summary(&_old_evac_stats));
4519 }
4520
4521 void G1CollectedHeap::free_region(HeapRegion* hr,
4522 FreeRegionList* free_list,
4523 bool par,
4524 bool locked) {
4525 assert(!hr->is_free(), "the region should not be free");
4526 assert(!hr->is_empty(), "the region should not be empty");
4527 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4528 assert(free_list != NULL, "pre-condition");
4529
4530 if (G1VerifyBitmaps) {
4531 MemRegion mr(hr->bottom(), hr->end());
4532 concurrent_mark()->clearRangePrevBitmap(mr);
4533 }
4534
4535 // Clear the card counts for this region.
4536 // Note: we only need to do this if the region is not young
4537 // (since we don't refine cards in young regions).
4538 if (!hr->is_young()) {
4539 _hot_card_cache->reset_card_counts(hr);
4540 }
4541 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4542 free_list->add_ordered(hr);
4543 }
4544
4545 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4546 FreeRegionList* free_list,
4547 bool par) {
4548 assert(hr->is_humongous(), "this is only for humongous regions");
4549 assert(free_list != NULL, "pre-condition");
4550 hr->clear_humongous();
4551 free_region(hr, free_list, par);
4552 }
4553
4554 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4555 const uint humongous_regions_removed) {
4556 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4557 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4558 _old_set.bulk_remove(old_regions_removed);
4559 _humongous_set.bulk_remove(humongous_regions_removed);
4560 }
4561
4562 }
4563
4564 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4565 assert(list != NULL, "list can't be null");
4566 if (!list->is_empty()) {
4567 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4568 _hrm.insert_list_into_free_list(list);
4569 }
4570 }
4571
4572 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4573 decrease_used(bytes);
4574 }
4575
4576 class G1ParScrubRemSetTask: public AbstractGangTask {
4577 protected:
4578 G1RemSet* _g1rs;
4579 HeapRegionClaimer _hrclaimer;
4580
4581 public:
4582 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4583 AbstractGangTask("G1 ScrubRS"),
4584 _g1rs(g1_rs),
4585 _hrclaimer(num_workers) {
4586 }
4587
4588 void work(uint worker_id) {
4589 _g1rs->scrub(worker_id, &_hrclaimer);
4590 }
4591 };
4592
4593 void G1CollectedHeap::scrub_rem_set() {
4594 uint num_workers = workers()->active_workers();
4595 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4596 workers()->run_task(&g1_par_scrub_rs_task);
4597 }
4598
4599 class G1FreeCollectionSetClosure : public HeapRegionClosure {
4600 private:
4601 const size_t* _surviving_young_words;
4602
4603 FreeRegionList _local_free_list;
4604 size_t _rs_lengths;
4605 // Bytes used in successfully evacuated regions before the evacuation.
4606 size_t _before_used_bytes;
4607 // Bytes used in unsucessfully evacuated regions before the evacuation
4608 size_t _after_used_bytes;
4609
4610 double _young_time;
4611 double _non_young_time;
4612 public:
4613 G1FreeCollectionSetClosure(const size_t* surviving_young_words) :
4614 HeapRegionClosure(),
4615 _surviving_young_words(surviving_young_words),
4616 _local_free_list("Local Region List for CSet Freeing"),
4617 _rs_lengths(0),
4618 _before_used_bytes(0),
4619 _after_used_bytes(0),
4620 _young_time(0.0),
4621 _non_young_time(0.0) {
4622 }
4623
4624 virtual bool doHeapRegion(HeapRegion* r) {
4625 double start_time = os::elapsedTime();
4626
4627 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4628 assert(!g1h->is_on_master_free_list(r), "sanity");
4629
4630 _rs_lengths += r->rem_set()->occupied_locked();
4631
4632 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4633 g1h->clear_in_cset(r);
4634
4635 if (r->is_young()) {
4636 int index = r->young_index_in_cset();
4637 assert(index != -1, "Young index in collection set must not be -1 for region %u", r->hrm_index());
4638 assert((uint) index < g1h->collection_set()->young_region_length(), "invariant");
4639 size_t words_survived = _surviving_young_words[index];
4640 r->record_surv_words_in_group(words_survived);
4641 } else {
4642 assert(r->young_index_in_cset() == -1, "Young index for old region %u in collection set must be -1", r->hrm_index());
4643 }
4644
4645 if (!r->evacuation_failed()) {
4646 MemRegion used_mr = r->used_region();
4647
4648 // And the region is empty.
4649 assert(!used_mr.is_empty(), "Should not have empty regions in a collection set.");
4650 _before_used_bytes += r->used();
4651 g1h->free_region(r, &_local_free_list, false /* par */, true /* locked */);
4652 } else {
4653 r->uninstall_surv_rate_group();
4654 r->set_young_index_in_cset(-1);
4655 r->set_evacuation_failed(false);
4656 // When moving a young gen region to old gen, we "allocate" that whole region
4657 // there. This is in addition to any already evacuated objects. Notify the
4658 // policy about that.
4659 // Old gen regions do not cause an additional allocation: both the objects
4660 // still in the region and the ones already moved are accounted for elsewhere.
4661 if (r->is_young()) {
4662 g1h->g1_policy()->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4663 }
4664 // The region is now considered to be old.
4665 r->set_old();
4666 // Do some allocation statistics accounting. Regions that failed evacuation
4667 // are always made old, so there is no need to update anything in the young
4668 // gen statistics, but we need to update old gen statistics.
4669 size_t used_words = r->marked_bytes() / HeapWordSize;
4670
4671 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4672 g1h->old_set_add(r);
4673 _after_used_bytes += r->used();
4674 }
4675
4676 if (r->is_young()) {
4677 _young_time += os::elapsedTime() - start_time;
4678 } else {
4679 _non_young_time += os::elapsedTime() - start_time;
4680 }
4681 return false;
4682 }
4683
4684 FreeRegionList* local_free_list() { return &_local_free_list; }
4685 size_t rs_lengths() const { return _rs_lengths; }
4686 size_t before_used_bytes() const { return _before_used_bytes; }
4687 size_t after_used_bytes() const { return _after_used_bytes; }
4688
4689 double young_time() const { return _young_time; }
4690 double non_young_time() const { return _non_young_time; }
4691 };
4692
4693 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4694 _eden.clear();
4695
4696 G1FreeCollectionSetClosure cl(surviving_young_words);
4697 collection_set_iterate(&cl);
4698
4699 evacuation_info.set_regions_freed(cl.local_free_list()->length());
4700 evacuation_info.increment_collectionset_used_after(cl.after_used_bytes());
4701
4702 G1Policy* policy = g1_policy();
4703
4704 policy->record_max_rs_lengths(cl.rs_lengths());
4705 policy->cset_regions_freed();
4706
4707 prepend_to_freelist(cl.local_free_list());
4708 decrement_summary_bytes(cl.before_used_bytes());
4709
4710 policy->phase_times()->record_young_free_cset_time_ms(cl.young_time() * 1000.0);
4711 policy->phase_times()->record_non_young_free_cset_time_ms(cl.non_young_time() * 1000.0);
4712
4713 collection_set->clear();
4714 }
4715
4716 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4717 private:
4718 FreeRegionList* _free_region_list;
4719 HeapRegionSet* _proxy_set;
4720 uint _humongous_regions_removed;
4721 size_t _freed_bytes;
4722 public:
4723
4724 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4725 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4726 }
4727
4728 virtual bool doHeapRegion(HeapRegion* r) {
4729 if (!r->is_starts_humongous()) {
4730 return false;
4731 }
4732
4733 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4734
4735 oop obj = (oop)r->bottom();
4736 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4737
4738 // The following checks whether the humongous object is live are sufficient.
4739 // The main additional check (in addition to having a reference from the roots
4740 // or the young gen) is whether the humongous object has a remembered set entry.
4741 //
4742 // A humongous object cannot be live if there is no remembered set for it
4743 // because:
4744 // - there can be no references from within humongous starts regions referencing
4745 // the object because we never allocate other objects into them.
4746 // (I.e. there are no intra-region references that may be missed by the
4747 // remembered set)
4748 // - as soon there is a remembered set entry to the humongous starts region
4749 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4750 // until the end of a concurrent mark.
4751 //
4752 // It is not required to check whether the object has been found dead by marking
4753 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4754 // all objects allocated during that time are considered live.
4755 // SATB marking is even more conservative than the remembered set.
4756 // So if at this point in the collection there is no remembered set entry,
4757 // nobody has a reference to it.
4758 // At the start of collection we flush all refinement logs, and remembered sets
4759 // are completely up-to-date wrt to references to the humongous object.
4760 //
4761 // Other implementation considerations:
4762 // - never consider object arrays at this time because they would pose
4763 // considerable effort for cleaning up the the remembered sets. This is
4764 // required because stale remembered sets might reference locations that
4765 // are currently allocated into.
4766 uint region_idx = r->hrm_index();
4767 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4768 !r->rem_set()->is_empty()) {
4769 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",
4770 region_idx,
4771 (size_t)obj->size() * HeapWordSize,
4772 p2i(r->bottom()),
4773 r->rem_set()->occupied(),
4774 r->rem_set()->strong_code_roots_list_length(),
4775 next_bitmap->isMarked(r->bottom()),
4776 g1h->is_humongous_reclaim_candidate(region_idx),
4777 obj->is_typeArray()
4778 );
4779 return false;
4780 }
4781
4782 guarantee(obj->is_typeArray(),
4783 "Only eagerly reclaiming type arrays is supported, but the object "
4784 PTR_FORMAT " is not.", p2i(r->bottom()));
4785
4786 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",
4787 region_idx,
4788 (size_t)obj->size() * HeapWordSize,
4789 p2i(r->bottom()),
4790 r->rem_set()->occupied(),
4791 r->rem_set()->strong_code_roots_list_length(),
4792 next_bitmap->isMarked(r->bottom()),
4793 g1h->is_humongous_reclaim_candidate(region_idx),
4794 obj->is_typeArray()
4795 );
4796
4797 // Need to clear mark bit of the humongous object if already set.
4798 if (next_bitmap->isMarked(r->bottom())) {
4799 next_bitmap->clear(r->bottom());
4800 }
4801 do {
4802 HeapRegion* next = g1h->next_region_in_humongous(r);
4803 _freed_bytes += r->used();
4804 r->set_containing_set(NULL);
4805 _humongous_regions_removed++;
4806 g1h->free_humongous_region(r, _free_region_list, false);
4807 r = next;
4808 } while (r != NULL);
4809
4810 return false;
4811 }
4812
4813 uint humongous_free_count() {
4814 return _humongous_regions_removed;
4815 }
4816
4817 size_t bytes_freed() const {
4818 return _freed_bytes;
4819 }
4820 };
4821
4822 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4823 assert_at_safepoint(true);
4824
4825 if (!G1EagerReclaimHumongousObjects ||
4826 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4827 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4828 return;
4829 }
4830
4831 double start_time = os::elapsedTime();
4832
4833 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4834
4835 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4836 heap_region_iterate(&cl);
4837
4838 remove_from_old_sets(0, cl.humongous_free_count());
4839
4840 G1HRPrinter* hrp = hr_printer();
4841 if (hrp->is_active()) {
4842 FreeRegionListIterator iter(&local_cleanup_list);
4843 while (iter.more_available()) {
4844 HeapRegion* hr = iter.get_next();
4845 hrp->cleanup(hr);
4846 }
4847 }
4848
4849 prepend_to_freelist(&local_cleanup_list);
4850 decrement_summary_bytes(cl.bytes_freed());
4851
4852 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4853 cl.humongous_free_count());
4854 }
4855
4856 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4857 public:
4858 virtual bool doHeapRegion(HeapRegion* r) {
4859 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4860 G1CollectedHeap::heap()->clear_in_cset(r);
4861 r->set_young_index_in_cset(-1);
4862 return false;
4863 }
4864 };
4865
4866 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4867 G1AbandonCollectionSetClosure cl;
4868 collection_set->iterate(&cl);
4869
4870 collection_set->clear();
4871 collection_set->stop_incremental_building();
4872 }
4873
4874 void G1CollectedHeap::set_free_regions_coming() {
4875 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4876
4877 assert(!free_regions_coming(), "pre-condition");
4878 _free_regions_coming = true;
4879 }
4880
4881 void G1CollectedHeap::reset_free_regions_coming() {
4882 assert(free_regions_coming(), "pre-condition");
4883
4884 {
4885 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4886 _free_regions_coming = false;
4887 SecondaryFreeList_lock->notify_all();
4888 }
4889
4890 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4891 }
4892
4893 void G1CollectedHeap::wait_while_free_regions_coming() {
4894 // Most of the time we won't have to wait, so let's do a quick test
4895 // first before we take the lock.
4896 if (!free_regions_coming()) {
4897 return;
4898 }
4899
4900 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4901
4902 {
4903 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4904 while (free_regions_coming()) {
4905 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4906 }
4907 }
4908
4909 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4910 }
4911
4912 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4913 return _allocator->is_retained_old_region(hr);
4914 }
4915
4916 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4917 _eden.add(hr);
4918 _g1_policy->set_region_eden(hr);
4919 }
4920
4921 #ifdef ASSERT
4922
4923 class NoYoungRegionsClosure: public HeapRegionClosure {
4924 private:
4925 bool _success;
4926 public:
4927 NoYoungRegionsClosure() : _success(true) { }
4928 bool doHeapRegion(HeapRegion* r) {
4929 if (r->is_young()) {
4930 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4931 p2i(r->bottom()), p2i(r->end()));
4932 _success = false;
4933 }
4934 return false;
4935 }
4936 bool success() { return _success; }
4937 };
4938
4939 bool G1CollectedHeap::check_young_list_empty() {
4940 bool ret = (young_regions_count() == 0);
4941
4942 NoYoungRegionsClosure closure;
4943 heap_region_iterate(&closure);
4944 ret = ret && closure.success();
4945
4946 return ret;
4947 }
4948
4949 #endif // ASSERT
4950
4951 class TearDownRegionSetsClosure : public HeapRegionClosure {
4952 private:
4953 HeapRegionSet *_old_set;
4954
4955 public:
4956 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4957
4958 bool doHeapRegion(HeapRegion* r) {
4959 if (r->is_old()) {
4960 _old_set->remove(r);
4961 } else if(r->is_young()) {
4962 r->uninstall_surv_rate_group();
4963 } else {
4964 // We ignore free regions, we'll empty the free list afterwards.
4965 // We ignore humongous regions, we're not tearing down the
4966 // humongous regions set.
4967 assert(r->is_free() || r->is_humongous(),
4968 "it cannot be another type");
4969 }
4970 return false;
4971 }
4972
4973 ~TearDownRegionSetsClosure() {
4974 assert(_old_set->is_empty(), "post-condition");
4975 }
4976 };
4977
4978 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4979 assert_at_safepoint(true /* should_be_vm_thread */);
4980
4981 if (!free_list_only) {
4982 TearDownRegionSetsClosure cl(&_old_set);
4983 heap_region_iterate(&cl);
4984
4985 // Note that emptying the _young_list is postponed and instead done as
4986 // the first step when rebuilding the regions sets again. The reason for
4987 // this is that during a full GC string deduplication needs to know if
4988 // a collected region was young or old when the full GC was initiated.
4989 }
4990 _hrm.remove_all_free_regions();
4991 }
4992
4993 void G1CollectedHeap::increase_used(size_t bytes) {
4994 _summary_bytes_used += bytes;
4995 }
4996
4997 void G1CollectedHeap::decrease_used(size_t bytes) {
4998 assert(_summary_bytes_used >= bytes,
4999 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5000 _summary_bytes_used, bytes);
5001 _summary_bytes_used -= bytes;
5002 }
5003
5004 void G1CollectedHeap::set_used(size_t bytes) {
5005 _summary_bytes_used = bytes;
5006 }
5007
5008 class RebuildRegionSetsClosure : public HeapRegionClosure {
5009 private:
5010 bool _free_list_only;
5011 HeapRegionSet* _old_set;
5012 HeapRegionManager* _hrm;
5013 size_t _total_used;
5014
5015 public:
5016 RebuildRegionSetsClosure(bool free_list_only,
5017 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5018 _free_list_only(free_list_only),
5019 _old_set(old_set), _hrm(hrm), _total_used(0) {
5020 assert(_hrm->num_free_regions() == 0, "pre-condition");
5021 if (!free_list_only) {
5022 assert(_old_set->is_empty(), "pre-condition");
5023 }
5024 }
5025
5026 bool doHeapRegion(HeapRegion* r) {
5027 if (r->is_empty()) {
5028 // Add free regions to the free list
5029 r->set_free();
5030 r->set_allocation_context(AllocationContext::system());
5031 _hrm->insert_into_free_list(r);
5032 } else if (!_free_list_only) {
5033
5034 if (r->is_humongous()) {
5035 // We ignore humongous regions. We left the humongous set unchanged.
5036 } else {
5037 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5038 // We now consider all regions old, so register as such. Leave
5039 // archive regions set that way, however, while still adding
5040 // them to the old set.
5041 if (!r->is_archive()) {
5042 r->set_old();
5043 }
5044 _old_set->add(r);
5045 }
5046 _total_used += r->used();
5047 }
5048
5049 return false;
5050 }
5051
5052 size_t total_used() {
5053 return _total_used;
5054 }
5055 };
5056
5057 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5058 assert_at_safepoint(true /* should_be_vm_thread */);
5059
5060 if (!free_list_only) {
5061 _eden.clear();
5062 _survivor.clear();
5063 }
5064
5065 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5066 heap_region_iterate(&cl);
5067
5068 if (!free_list_only) {
5069 set_used(cl.total_used());
5070 if (_archive_allocator != NULL) {
5071 _archive_allocator->clear_used();
5072 }
5073 }
5074 assert(used_unlocked() == recalculate_used(),
5075 "inconsistent used_unlocked(), "
5076 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5077 used_unlocked(), recalculate_used());
5078 }
5079
5080 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5081 _refine_cte_cl->set_concurrent(concurrent);
5082 }
5083
5084 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5085 HeapRegion* hr = heap_region_containing(p);
5086 return hr->is_in(p);
5087 }
5088
5089 // Methods for the mutator alloc region
5090
5091 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5092 bool force) {
5093 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5094 assert(!force || g1_policy()->can_expand_young_list(),
5095 "if force is true we should be able to expand the young list");
5096 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5097 if (force || should_allocate) {
5098 HeapRegion* new_alloc_region = new_region(word_size,
5099 false /* is_old */,
5100 false /* do_expand */);
5101 if (new_alloc_region != NULL) {
5102 set_region_short_lived_locked(new_alloc_region);
5103 _hr_printer.alloc(new_alloc_region, !should_allocate);
5104 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5105 return new_alloc_region;
5106 }
5107 }
5108 return NULL;
5109 }
5110
5111 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5112 size_t allocated_bytes) {
5113 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5114 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5115
5116 collection_set()->add_eden_region(alloc_region);
5117 increase_used(allocated_bytes);
5118 _hr_printer.retire(alloc_region);
5119 // We update the eden sizes here, when the region is retired,
5120 // instead of when it's allocated, since this is the point that its
5121 // used space has been recored in _summary_bytes_used.
5122 g1mm()->update_eden_size();
5123 }
5124
5125 // Methods for the GC alloc regions
5126
5127 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5128 if (dest.is_old()) {
5129 return true;
5130 } else {
5131 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5132 }
5133 }
5134
5135 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5136 assert(FreeList_lock->owned_by_self(), "pre-condition");
5137
5138 if (!has_more_regions(dest)) {
5139 return NULL;
5140 }
5141
5142 const bool is_survivor = dest.is_young();
5143
5144 HeapRegion* new_alloc_region = new_region(word_size,
5145 !is_survivor,
5146 true /* do_expand */);
5147 if (new_alloc_region != NULL) {
5148 // We really only need to do this for old regions given that we
5149 // should never scan survivors. But it doesn't hurt to do it
5150 // for survivors too.
5151 new_alloc_region->record_timestamp();
5152 if (is_survivor) {
5153 new_alloc_region->set_survivor();
5154 _survivor.add(new_alloc_region);
5155 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5156 } else {
5157 new_alloc_region->set_old();
5158 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5159 }
5160 _hr_printer.alloc(new_alloc_region);
5161 bool during_im = collector_state()->during_initial_mark_pause();
5162 new_alloc_region->note_start_of_copying(during_im);
5163 return new_alloc_region;
5164 }
5165 return NULL;
5166 }
5167
5168 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5169 size_t allocated_bytes,
5170 InCSetState dest) {
5171 bool during_im = collector_state()->during_initial_mark_pause();
5172 alloc_region->note_end_of_copying(during_im);
5173 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5174 if (dest.is_old()) {
5175 _old_set.add(alloc_region);
5176 }
5177 _hr_printer.retire(alloc_region);
5178 }
5179
5180 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5181 bool expanded = false;
5182 uint index = _hrm.find_highest_free(&expanded);
5183
5184 if (index != G1_NO_HRM_INDEX) {
5185 if (expanded) {
5186 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5187 HeapRegion::GrainWords * HeapWordSize);
5188 }
5189 _hrm.allocate_free_regions_starting_at(index, 1);
5190 return region_at(index);
5191 }
5192 return NULL;
5193 }
5194
5195 // Optimized nmethod scanning
5196
5197 class RegisterNMethodOopClosure: public OopClosure {
5198 G1CollectedHeap* _g1h;
5199 nmethod* _nm;
5200
5201 template <class T> void do_oop_work(T* p) {
5202 T heap_oop = oopDesc::load_heap_oop(p);
5203 if (!oopDesc::is_null(heap_oop)) {
5204 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5205 HeapRegion* hr = _g1h->heap_region_containing(obj);
5206 assert(!hr->is_continues_humongous(),
5207 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5208 " starting at " HR_FORMAT,
5209 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5210
5211 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5212 hr->add_strong_code_root_locked(_nm);
5213 }
5214 }
5215
5216 public:
5217 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5218 _g1h(g1h), _nm(nm) {}
5219
5220 void do_oop(oop* p) { do_oop_work(p); }
5221 void do_oop(narrowOop* p) { do_oop_work(p); }
5222 };
5223
5224 class UnregisterNMethodOopClosure: public OopClosure {
5225 G1CollectedHeap* _g1h;
5226 nmethod* _nm;
5227
5228 template <class T> void do_oop_work(T* p) {
5229 T heap_oop = oopDesc::load_heap_oop(p);
5230 if (!oopDesc::is_null(heap_oop)) {
5231 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5232 HeapRegion* hr = _g1h->heap_region_containing(obj);
5233 assert(!hr->is_continues_humongous(),
5234 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5235 " starting at " HR_FORMAT,
5236 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5237
5238 hr->remove_strong_code_root(_nm);
5239 }
5240 }
5241
5242 public:
5243 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5244 _g1h(g1h), _nm(nm) {}
5245
5246 void do_oop(oop* p) { do_oop_work(p); }
5247 void do_oop(narrowOop* p) { do_oop_work(p); }
5248 };
5249
5250 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5251 CollectedHeap::register_nmethod(nm);
5252
5253 guarantee(nm != NULL, "sanity");
5254 RegisterNMethodOopClosure reg_cl(this, nm);
5255 nm->oops_do(®_cl);
5256 }
5257
5258 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5259 CollectedHeap::unregister_nmethod(nm);
5260
5261 guarantee(nm != NULL, "sanity");
5262 UnregisterNMethodOopClosure reg_cl(this, nm);
5263 nm->oops_do(®_cl, true);
5264 }
5265
5266 void G1CollectedHeap::purge_code_root_memory() {
5267 double purge_start = os::elapsedTime();
5268 G1CodeRootSet::purge();
5269 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5270 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5271 }
5272
5273 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5274 G1CollectedHeap* _g1h;
5275
5276 public:
5277 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5278 _g1h(g1h) {}
5279
5280 void do_code_blob(CodeBlob* cb) {
5281 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5282 if (nm == NULL) {
5283 return;
5284 }
5285
5286 if (ScavengeRootsInCode) {
5287 _g1h->register_nmethod(nm);
5288 }
5289 }
5290 };
5291
5292 void G1CollectedHeap::rebuild_strong_code_roots() {
5293 RebuildStrongCodeRootClosure blob_cl(this);
5294 CodeCache::blobs_do(&blob_cl);
5295 }