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annotate src/share/vm/gc_implementation/shared/concurrentGCThread.hpp @ 1842:6e0aac35bfa9
6980838: G1: guarantee(false) failed: thread has an unexpected active value in its SATB queue
Summary: Under certain circumstances a safepoint could happen between a JavaThread object being created and that object being added to the Java threads list. This could cause the active field of that thread's SATB queue to get out-of-sync with respect to the other Java threads. The solution is to activate the SATB queue, when necessary, before adding the thread to the Java threads list, not when the JavaThread object is created. The changeset also includes a small fix to rename the surrogate locker thread from "Surrogate Locker Thread (CMS)" to "Surrogate Locker Thread (Concurrent GC)" since it's also used in G1.
Reviewed-by: iveresov, ysr, johnc, jcoomes
| author | tonyp |
|---|---|
| date | Fri, 01 Oct 2010 16:43:05 -0400 |
| parents | c18cbe5936b8 |
| children | f95d63e2154a |
| rev | line source |
|---|---|
| 342 | 1 /* |
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2 * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved. |
| 342 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 342 | 22 * |
| 23 */ | |
| 24 | |
| 25 class VoidClosure; | |
| 26 | |
| 27 // A SuspendibleThreadSet is (obviously) a set of threads that can be | |
| 28 // suspended. A thread can join and later leave the set, and periodically | |
| 29 // yield. If some thread (not in the set) requests, via suspend_all, that | |
| 30 // the threads be suspended, then the requesting thread is blocked until | |
| 31 // all the threads in the set have yielded or left the set. (Threads may | |
| 32 // not enter the set when an attempted suspension is in progress.) The | |
| 33 // suspending thread later calls resume_all, allowing the suspended threads | |
| 34 // to continue. | |
| 35 | |
| 36 class SuspendibleThreadSet { | |
| 37 Monitor* _m; | |
| 38 int _async; | |
| 39 bool _async_stop; | |
| 40 int _async_stopped; | |
| 41 bool _initialized; | |
| 42 double _suspend_all_start; | |
| 43 | |
| 44 void initialize_work(); | |
| 45 | |
| 46 public: | |
| 47 SuspendibleThreadSet() : _initialized(false) {} | |
| 48 | |
| 49 // Add the current thread to the set. May block if a suspension | |
| 50 // is in progress. | |
| 51 void join(); | |
| 52 // Removes the current thread from the set. | |
| 53 void leave(); | |
| 54 // Returns "true" iff an suspension is in progress. | |
| 55 bool should_yield() { return _async_stop; } | |
| 56 // Suspends the current thread if a suspension is in progress (for | |
| 57 // the duration of the suspension.) | |
| 58 void yield(const char* id); | |
| 59 // Return when all threads in the set are suspended. | |
| 60 void suspend_all(); | |
| 61 // Allow suspended threads to resume. | |
| 62 void resume_all(); | |
| 63 // Redundant initializations okay. | |
| 64 void initialize() { | |
| 65 // Double-check dirty read idiom. | |
| 66 if (!_initialized) initialize_work(); | |
| 67 } | |
| 68 }; | |
| 69 | |
| 70 | |
| 71 class ConcurrentGCThread: public NamedThread { | |
| 72 friend class VMStructs; | |
| 73 | |
| 74 protected: | |
| 794 | 75 bool _should_terminate; |
| 76 bool _has_terminated; | |
| 342 | 77 |
| 78 enum CGC_flag_type { | |
| 79 CGC_nil = 0x0, | |
| 80 CGC_dont_suspend = 0x1, | |
| 81 CGC_CGC_safepoint = 0x2, | |
| 82 CGC_VM_safepoint = 0x4 | |
| 83 }; | |
| 84 | |
| 85 static int _CGC_flag; | |
| 86 | |
| 87 static bool CGC_flag_is_set(int b) { return (_CGC_flag & b) != 0; } | |
| 88 static int set_CGC_flag(int b) { return _CGC_flag |= b; } | |
| 89 static int reset_CGC_flag(int b) { return _CGC_flag &= ~b; } | |
| 90 | |
| 91 void stopWorldAndDo(VoidClosure* op); | |
| 92 | |
| 93 // All instances share this one set. | |
| 94 static SuspendibleThreadSet _sts; | |
| 95 | |
| 96 // Create and start the thread (setting it's priority high.) | |
| 97 void create_and_start(); | |
| 98 | |
| 99 // Do initialization steps in the thread: record stack base and size, | |
| 100 // init thread local storage, set JNI handle block. | |
| 101 void initialize_in_thread(); | |
| 102 | |
| 103 // Wait until Universe::is_fully_initialized(); | |
| 104 void wait_for_universe_init(); | |
| 105 | |
| 106 // Record that the current thread is terminating, and will do more | |
| 107 // concurrent work. | |
| 108 void terminate(); | |
| 109 | |
| 110 public: | |
| 111 // Constructor | |
| 112 | |
| 113 ConcurrentGCThread(); | |
| 114 ~ConcurrentGCThread() {} // Exists to call NamedThread destructor. | |
| 115 | |
| 116 // Tester | |
| 117 bool is_ConcurrentGC_thread() const { return true; } | |
| 118 | |
| 119 static void safepoint_synchronize(); | |
| 120 static void safepoint_desynchronize(); | |
| 121 | |
| 122 // All overridings should probably do _sts::yield, but we allow | |
| 123 // overriding for distinguished debugging messages. Default is to do | |
| 124 // nothing. | |
| 125 virtual void yield() {} | |
| 126 | |
| 127 bool should_yield() { return _sts.should_yield(); } | |
| 128 | |
| 129 // they are prefixed by sts since there are already yield() and | |
| 130 // should_yield() (non-static) methods in this class and it was an | |
| 131 // easy way to differentiate them. | |
| 132 static void stsYield(const char* id); | |
| 133 static bool stsShouldYield(); | |
| 134 static void stsJoin(); | |
| 135 static void stsLeave(); | |
| 136 | |
| 137 }; | |
| 138 | |
| 139 // The SurrogateLockerThread is used by concurrent GC threads for | |
| 140 // manipulating Java monitors, in particular, currently for | |
| 141 // manipulating the pending_list_lock. XXX | |
| 142 class SurrogateLockerThread: public JavaThread { | |
| 143 friend class VMStructs; | |
| 144 public: | |
| 145 enum SLT_msg_type { | |
| 146 empty = 0, // no message | |
| 147 acquirePLL, // acquire pending list lock | |
| 148 releaseAndNotifyPLL // notify and release pending list lock | |
| 149 }; | |
| 150 private: | |
| 151 // the following are shared with the CMSThread | |
| 152 SLT_msg_type _buffer; // communication buffer | |
| 153 Monitor _monitor; // monitor controlling buffer | |
| 154 BasicLock _basicLock; // used for PLL locking | |
| 155 | |
| 156 public: | |
| 157 static SurrogateLockerThread* make(TRAPS); | |
| 158 | |
| 159 SurrogateLockerThread(); | |
| 160 | |
| 161 bool is_hidden_from_external_view() const { return true; } | |
| 162 | |
| 163 void loop(); // main method | |
| 164 | |
| 165 void manipulatePLL(SLT_msg_type msg); | |
| 166 | |
| 167 }; |