Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/g1StringDedupQueue.hpp @ 20504:6948da6d7c13
8052172: Evacuation failure handling in G1 does not evacuate all objects if -XX:-G1DeferredRSUpdate is set
Summary: Remove -XX:-G1DeferredRSUpdate functionality as it is racy. During evacuation failure handling, threads where evacuation failure handling occurred may try to add remembered sets to regions which remembered sets are currently being scanned. The iterator to handle the remembered set scan does not support addition of entries during scan and so may skip valid references.
Reviewed-by: iveresov, brutisso, mgerdin
| author | tschatzl |
|---|---|
| date | Tue, 30 Sep 2014 09:44:36 +0200 |
| parents | 1772223a25a2 |
| children |
| rev | line source |
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| 17764 | 1 /* |
| 2 * Copyright (c) 2014, 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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP | |
| 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP | |
| 27 | |
| 28 #include "memory/allocation.hpp" | |
| 29 #include "oops/oop.hpp" | |
| 30 #include "utilities/stack.hpp" | |
| 31 | |
| 32 class G1StringDedupUnlinkOrOopsDoClosure; | |
| 33 | |
| 34 // | |
| 35 // The deduplication queue acts as the communication channel between the stop-the-world | |
| 36 // mark/evacuation phase and the concurrent deduplication phase. Deduplication candidates | |
| 37 // found during mark/evacuation are placed on this queue for later processing in the | |
| 38 // deduplication thread. A queue entry is an oop pointing to a String object (as opposed | |
| 39 // to entries in the deduplication hashtable which points to character arrays). | |
| 40 // | |
| 41 // While users of the queue treat it as a single queue, it is implemented as a set of | |
| 42 // queues, one queue per GC worker thread, to allow lock-free and cache-friendly enqueue | |
| 43 // operations by the GC workers. | |
| 44 // | |
| 45 // The oops in the queue are treated as weak pointers, meaning the objects they point to | |
| 46 // can become unreachable and pruned (cleared) before being popped by the deduplication | |
| 47 // thread. | |
| 48 // | |
| 49 // Pushing to the queue is thread safe (this relies on each thread using a unique worker | |
| 50 // id), but only allowed during a safepoint. Popping from the queue is NOT thread safe | |
| 51 // and can only be done by the deduplication thread outside a safepoint. | |
| 52 // | |
| 53 // The StringDedupQueue_lock is only used for blocking and waking up the deduplication | |
| 54 // thread in case the queue is empty or becomes non-empty, respectively. This lock does | |
| 55 // not otherwise protect the queue content. | |
| 56 // | |
| 57 class G1StringDedupQueue : public CHeapObj<mtGC> { | |
| 58 private: | |
| 59 typedef Stack<oop, mtGC> G1StringDedupWorkerQueue; | |
| 60 | |
| 61 static G1StringDedupQueue* _queue; | |
| 62 static const size_t _max_size; | |
| 63 static const size_t _max_cache_size; | |
| 64 | |
| 65 G1StringDedupWorkerQueue* _queues; | |
| 66 size_t _nqueues; | |
| 67 size_t _cursor; | |
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68 bool _cancel; |
| 17764 | 69 volatile bool _empty; |
| 70 | |
| 71 // Statistics counter, only used for logging. | |
| 72 uintx _dropped; | |
| 73 | |
| 74 G1StringDedupQueue(); | |
| 75 ~G1StringDedupQueue(); | |
| 76 | |
| 77 static void unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl, size_t queue); | |
| 78 | |
| 79 public: | |
| 80 static void create(); | |
| 81 | |
| 82 // Blocks and waits for the queue to become non-empty. | |
| 83 static void wait(); | |
| 84 | |
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85 // Wakes up any thread blocked waiting for the queue to become non-empty. |
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8037112: gc/g1/TestHumongousAllocInitialMark.java caused SIGSEGV
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86 static void cancel_wait(); |
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8037112: gc/g1/TestHumongousAllocInitialMark.java caused SIGSEGV
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87 |
| 17764 | 88 // Pushes a deduplication candidate onto a specific GC worker queue. |
| 89 static void push(uint worker_id, oop java_string); | |
| 90 | |
| 91 // Pops a deduplication candidate from any queue, returns NULL if | |
| 92 // all queues are empty. | |
| 93 static oop pop(); | |
| 94 | |
| 95 static void unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl); | |
| 96 | |
| 97 static void print_statistics(outputStream* st); | |
| 98 static void verify(); | |
| 99 }; | |
| 100 | |
| 101 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1STRINGDEDUPQUEUE_HPP |