APPARENT DEADLOCK为未分配的待处理任务创建紧急线程

问题描述 投票：20回答：3

我在mybatis上使用mysql，我在我们的实时服务器上遇到这个错误

com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@6538f8f2 
-- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!

我不明白为什么这个错误会因为我的C3P0设置而来？我的C3P0设置是这样的

----开始更新-----

下面是我的spring-servlet.xml配置

我将datasource bean更新为

<bean id="datasource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close" p:driverClass="com.mysql.jdbc.Driver"
p:jdbcUrl="jdbc:mysql://localhost/jdb" p:user="root" p:password="root" 
p:acquireIncrement="10" 
p:idleConnectionTestPeriod="60"
p:maxPoolSize="100" 
    p:maxStatements="0" 
    p:minPoolSize="10" 
    p:initialPoolSize="10"
    p:statementCacheNumDeferredCloseThreads="1" />
   <!-- Declare a transaction manager -->

<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager"
p:dataSource-ref="datasource" />


<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="datasource" />
</bean>

<!-- scan for mappers and will automatically scan the whole classpath for xmls -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="sqlSessionFactory" ref="sqlSessionFactory" />
    <property name="basePackage" value="com.mycom.myproject.db.mybatis.dao" />
</bean>

从我的Dao类中我称之为mapper方法

 myDao.updateRecords()

这是我的服务类方法

@Override
public List<UserDetailedBean> selectAllUsersDetail(long groupId, List<Long> ids) {

    List<UserDetailedBean> usersDetailList = null;

    try {
        usersDetailList = userDao.selectAllUsersDetail(groupId, ids);
    } catch (Exception e) {
        e.printStackTrace();
    }

    return usersDetailList;
}

在Dao类我只是注入映射器。

@Resource
private UserMapper userMapper;

@Override
public List<UserDetailedBean> selectAllUsersDetail(long groupId, List<Long> ids) {
    return userMapper.selectAllUsersDetail(groupId,ids);
}

---结束更新------

如果需要任何其他信息，请告诉我。

这是完整的堆栈跟踪

[ WARN] 2013-01-08 20:13:39       com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@70497e11 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
[ WARN] 2013-01-08 20:13:39 com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@70497e11 -- APPARENT DEADLOCK!!! Complete Status: 
 Managed Threads: 3
 Active Threads: 3
 Active Tasks: 
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@2e81b8c5 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@4689a55d (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@76c7a0d8 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
 Pending Tasks: 
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@2c1101d4
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@108f1be6
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@2370a188
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@377cf9e5
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@6dfa45d8
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@49ffa050
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@2d760a24
    Pool thread stack traces:
 Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
     java.net.SocketInputStream.socketRead0(Native Method)
     java.net.SocketInputStream.read(SocketInputStream.java:150)
     java.net.SocketInputStream.read(SocketInputStream.java:121)
     com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
     com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
     com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
     com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2549)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3002)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2991)
     com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3532)
     com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
     com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2618)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
     com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1557)
     com.mysql.jdbc.DatabaseMetaData$9.forEach(DatabaseMetaData.java:4984)
     com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:51)
     com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:4962)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
     com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:310)
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
     com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
 Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
     java.net.SocketInputStream.socketRead0(Native Method)
     java.net.SocketInputStream.read(SocketInputStream.java:150)
     java.net.SocketInputStream.read(SocketInputStream.java:121)
     com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
     com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
     com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
     com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2549)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3002)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2991)
     com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3532)
     com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
     com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2618)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
     com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1557)
     com.mysql.jdbc.DatabaseMetaData$9.forEach(DatabaseMetaData.java:4984)
     com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:51)
     com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:4962)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
     com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:310)
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
     com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
 Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
     java.net.SocketInputStream.socketRead0(Native Method)
     java.net.SocketInputStream.read(SocketInputStream.java:150)
     java.net.SocketInputStream.read(SocketInputStream.java:121)
     com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
     com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
     com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
     com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2549)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3002)
     com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2991)
     com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3532)
     com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
     com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2618)
     com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
     com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1557)
     com.mysql.jdbc.DatabaseMetaData$9.forEach(DatabaseMetaData.java:4984)
     com.mysql.jdbc.IterateBlock.doForAll(IterateBlock.java:51)
     com.mysql.jdbc.DatabaseMetaData.getTables(DatabaseMetaData.java:4962)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnectionNoQuery(DefaultConnectionTester.java:185)
     com.mchange.v2.c3p0.impl.DefaultConnectionTester.activeCheckConnection(DefaultConnectionTester.java:62)
     com.mchange.v2.c3p0.AbstractConnectionTester.activeCheckConnection(AbstractConnectionTester.java:67)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
     com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishIdleResource(C3P0PooledConnectionPool.java:310)
     com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.run(BasicResourcePool.java:1999)
     com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

- -更新 - -

当我将p：statementCacheNumDeferredCloseThreads =“1”添加到datasouce bean时，我收到以下错误

     Error creating bean with name 'sqlSessionFactory' defined in ServletContext resource [/WEB-INF/spring-servlet.xml]: 
     Cannot resolve reference to bean 'datasource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'datasource' defined in ServletContext resource [/WEB-INF/spring-servlet.xml]: 
   Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'statementCacheNumDeferredCloseThreads' of bean class [com.mchange.v2.c3p0.ComboPooledDataSource]: 
   Bean property 'statementCacheNumDeferredCloseThreads' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
java mysql jdbc mybatis
3个回答
17
投票

来自http://www.mchange.com/projects/c3p0/#other_ds_configuration

numHelperThreads和maxAdministrativeTaskTime有助于配置DataSource线程池的行为。默认情况下，每个DataSource只有三个关联的帮助程序线程。如果性能似乎在重负载下拖拽，或者如果您通过JMX观察或直接检查PooledDataSource，那么“待处理任务”的数量通常大于零，请尝试增加numHelperThreads。对于遇到无限期挂起的任务和“APPARENT DEADLOCK”消息的用户，maxAdministrativeTaskTime可能很有用。 （有关更多信息，请参阅附录A.）

maxAdministrativeTaskTime默认值：0在c3p0的线程池之前的秒数将尝试中断一个明显挂起的任务。很少有用。许多c3p0的函数不是由客户端线程执行的，而是由内部线程池异步执行的。 c3p0的异步直接增强了客户端性能，并通过确保在非锁定保持线程中执行慢速jdbc操作，最大限度地缩短了关键锁定所需的时间。但是，如果这些任务中的某些任务“挂起”，那就是它们既没有成功也没有因为Exception长时间失败，c3p0的线程池可能会耗尽并且备份管理任务。如果任务很慢，解决问题的最佳方法是通过numHelperThreads增加线程数。但是，如果任务有时无限期挂起，则可以使用此参数强制调用任务线程的interrupt（）方法（如果任务超出设定的时间限制）。 [c3p0最终将通过发出“APPARENT DEADLOCK”信号来恢复挂起的任务（您将在日志中看到它作为警告），替换线程池任务线程，并中断（）原始线程。但让游泳池进入APPARENT DEADLOCK然后恢复意味着在某些时期，c3p0的性能将受损。因此，如果您看到这些消息，增加numHelperThreads和设置maxAdministrativeTaskTime可能会有所帮助。 maxAdministrativeTaskTime应该足够大，以至于任何合理的尝试从数据库获取连接，测试连接或两个销毁连接，都应该在设置的时间内成功或失败。零（默认值）表示任务永远不会中断，这是大多数情况下最好，最安全的策略。如果任务很慢，请分配更多线程。如果任务永远悬空，请尝试弄清楚原因，并且在此期间设置maxAdministrativeTaskTime可能会有所帮助。

The default is 3 for numHelperThreads , increase this to 8-10 

setting maxAdministrativeTaskTime will help
11
投票

请查看解决问题的后续步骤：

  1. 在ComboPooledDataSource中增加p:maxStatements。
  2. 将p:maxStatements设置为0.例如在Firebird中，这个hack可以使用ComboPooledDataSource。
  3. 请务必在申请表中关闭SqlSession。更加注意集中执行数据库操作。在我的mySql JDBC驱动程序版本中：当对象被垃圾收集时，mysql-connector-java 5.1.8连接会自动关闭。因此，在您的情况下，如果您不密集使用数据库，则连接不应泄漏。不过你必须确保你关闭了将jdbc连接包装到DB的myBatis SqlSession。
  4. 因此JDBC3 Connection and Statement Pooling也可以尝试在c3p0配置中将statementCacheNumDeferredCloseThreads设置为1。
0
投票

在我的情况下，应用程序的内存太少是原因。使用的数据库是H2或SQLite（这两个都在这个应用程序中使用）。

第一个症状是上面报告的这些WARN日志行：

12006925 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|33af2d37]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@6d3a9c65 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12016284 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|3d98d1b]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@44565f94 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12051847 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|5703a6aa]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@c9f37e2 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12085128 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|4e50d42b]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@6f1927b7 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12085128 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|78fa7f84]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@22c22b50 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
12172644 [C3P0PooledConnectionPoolManager[identityToken->2rvy8f9szmpczp1k2dm1g|e8e88fa]-AdminTaskTimer] WARN  com.mchange.v2.async.ThreadPoolAsynchronousRunner  - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@745a644f -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!

经过很长一段时间的例外，包括揭示：

Caused by: java.lang.OutOfMemoryError: GC overhead limit exceeded

这个问题是可以重现的。为应用程序提供更多内存（-Xmx8G）修复它。

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