mysql - 如何使用 c3p0 进行节点故障转移测试

标签 mysql c3p0 mysql-connector mysql-cluster connector-j

我们已经设置了具有三个节点的 MySQL NDB Cluster，以下是设置的详细信息。
Node1 - 多线程DataNode1、SQLNode1
Node2 - 多线程DataNode2、SQLNode2
Node3 - 管理节点

我们正在测试一些故障转移场景，以确保设置有效。在客户端，我们使用 MySQLConnector v5.1.30 以及 c3p0 连接池。客户端配置了多主控参数。因此，如果其中一个节点或应用程序出现故障，则应在另一个节点上执行 JDBC 查询并继续响应。

但是当 SQLNode(端口:3306)出现故障时，我们观察到异常行为。连接不会故障转移到另一个节点。

配置如下:

<bean id="myDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
                destroy-method="close">
        <property name="driverClass" value="com.mysql.jdbc.ReplicationDriver" />                            <!-- useConfigs=clusterBase -->
        <property name="jdbcUrl" value="jdbc:mysql:replication://192.168.102.22,192.168.102.23/hhmefep?autoReconnect=true&amp;failOverReadOnly=false&amp;roundRobinLoadBalance=true" /> 
        <property name="user" value="root"/>
        <property name="password" value="changeit"/>
        <property name="acquireIncrement" value="2" />
        <property name="minPoolSize" value="50" />
        <property name="maxPoolSize" value="100" />
        <property name="maxStatements" value="2000" />
        <property name="maxIdleTime" value="3600" />
        <property name="connectionTesterClassName" value="com.mysql.jdbc.integration.c3p0.MysqlConnectionTester" />
        <property name="testConnectionOnCheckin" value="true" />
        <property name="testConnectionOnCheckout" value="false" />
        <property name="idleConnectionTestPeriod" value="30" />
    </bean>

当我启动客户端时，这两个节点已启动并正在运行。 之后，我从第一个节点(192.168.102.22)终止 mysqld 进程，我得到以下 stackTrace，

org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.loader.Loader.doList(Loader.java:2536)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
at org.hibernate.loader.Loader.list(Loader.java:2271)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1716)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
at com.mi.persistence.dao.cdr.BganActiveCallsDaoImpl.findBganActiveCallsBy_Imsi_Nsapi_Apn(BganActiveCallsDaoImpl.java:53)
at sun.reflect.GeneratedMethodAccessor283.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at $Proxy23.findBganActiveCallsBy_Imsi_Nsapi_Apn(Unknown Source)
at com.mi.persistence.service.cdr.BganActiveCallsServiceImpl.findBganActiveCallsBy_Imsi_Nsapi_Apn(BganActiveCallsServiceImpl.java:22)
at sun.reflect.GeneratedMethodAccessor282.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at $Proxy24.findBganActiveCallsBy_Imsi_Nsapi_Apn(Unknown Source)
at com.mi.persistence.service.callhandler.BganAccessRequestServiceImpl.getPreeptedCalls(BganAccessRequestServiceImpl.java:384)
at com.mi.taskobjects.externalsigobj.radiusobj.BGANAccessRequest.process(BGANAccessRequest.java:175)
at com.mi.entities.scheduler.SchWorkerThread.run(SchWorkerThread.java:165)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 19,578 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.
at sun.reflect.GeneratedConstructorAccessor66.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1127)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3715)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3604)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4155)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2615)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2776)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2838)
at com.mysql.jdbc.LoadBalancedMySQLConnection.execSQL(LoadBalancedMySQLConnection.java:159)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2082)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2212)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1953)
at org.hibernate.loader.Loader.doQuery(Loader.java:802)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
at org.hibernate.loader.Loader.doList(Loader.java:2533)
... 42 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3161)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3615)
... 56 more
Apr 24, 2014 2:13:13 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@18138d9 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
Apr 24, 2014 2:13:13 PM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@18138d9 -- APPARENT DEADLOCK!!! Complete Status: 
Managed Threads: 3
Active Threads: 3
Active Tasks: 
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@2dbdcf (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1088a28 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1a67efd (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
Pending Tasks: 
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@1db547d
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask@87fa45
    com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StatementCloseTask@13fcd69
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1c6dc6d
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@b198d1
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1a7ce01
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@1c5be25
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1469706
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@1654503
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@195f1b4
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@12f893d
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1db4400
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@4d7ab3
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@b29aa5
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@1c6fb4f
    com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@9d2c8e
    com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@d843e0
    com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask@504b76
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@18a408c
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@193e4a4
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@87d60d
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1f6002a
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@184e113
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@d4bbb0
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@6e4a4c
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@cfc9f4
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1d3c0f3
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@120989c
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1034f45
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@497a1b
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1ef8e0b
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@568dc9
    com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@76bb9c
Pool thread stack traces:
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
    java.lang.Thread.sleep(Native Method)
    com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2396)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2326)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    sun.reflect.GeneratedConstructorAccessor27.newInstance(Unknown Source)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    com.mysql.jdbc.LoadBalancingConnectionProxy.createConnectionForHost(LoadBalancingConnectionProxy.java:383)
    com.mysql.jdbc.RandomBalanceStrategy.pickConnection(RandomBalanceStrategy.java:75)
    com.mysql.jdbc.LoadBalancingConnectionProxy.pickNewConnection(LoadBalancingConnectionProxy.java:711)
    com.mysql.jdbc.LoadBalancingConnectionProxy.dealWithInvocationException(LoadBalancingConnectionProxy.java:415)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:654)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:549)
    $Proxy22.ping(Unknown Source)
    com.mysql.jdbc.ReplicationConnection.ping(ReplicationConnection.java:986)
    sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    com.mchange.v2.c3p0.impl.NewProxyConnection.rawConnectionOperation(NewProxyConnection.java:1315)
    com.mysql.jdbc.integration.c3p0.MysqlConnectionTester.activeCheckConnection(MysqlConnectionTester.java:78)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishResourceOnCheckin(C3P0PooledConnectionPool.java:301)
    com.mchange.v2.resourcepool.BasicResourcePool.attemptRefurbishResourceOnCheckin(BasicResourcePool.java:1606)
    com.mchange.v2.resourcepool.BasicResourcePool.access$200(BasicResourcePool.java:32)
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1228)
    com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
    java.lang.Thread.sleep(Native Method)
    com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2396)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2326)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    sun.reflect.GeneratedConstructorAccessor27.newInstance(Unknown Source)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    com.mysql.jdbc.LoadBalancingConnectionProxy.createConnectionForHost(LoadBalancingConnectionProxy.java:383)
    com.mysql.jdbc.RandomBalanceStrategy.pickConnection(RandomBalanceStrategy.java:75)
    com.mysql.jdbc.LoadBalancingConnectionProxy.pickNewConnection(LoadBalancingConnectionProxy.java:711)
    com.mysql.jdbc.LoadBalancingConnectionProxy.dealWithInvocationException(LoadBalancingConnectionProxy.java:415)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:654)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:549)
    $Proxy22.ping(Unknown Source)
    com.mysql.jdbc.ReplicationConnection.ping(ReplicationConnection.java:986)
    sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    com.mchange.v2.c3p0.impl.NewProxyConnection.rawConnectionOperation(NewProxyConnection.java:1315)
    com.mysql.jdbc.integration.c3p0.MysqlConnectionTester.activeCheckConnection(MysqlConnectionTester.java:78)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishResourceOnCheckin(C3P0PooledConnectionPool.java:301)
    com.mchange.v2.resourcepool.BasicResourcePool.attemptRefurbishResourceOnCheckin(BasicResourcePool.java:1606)
    com.mchange.v2.resourcepool.BasicResourcePool.access$200(BasicResourcePool.java:32)
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1228)
    com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
    java.lang.Thread.sleep(Native Method)
    com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2396)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2326)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    sun.reflect.GeneratedConstructorAccessor27.newInstance(Unknown Source)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    com.mysql.jdbc.LoadBalancingConnectionProxy.createConnectionForHost(LoadBalancingConnectionProxy.java:383)
    com.mysql.jdbc.RandomBalanceStrategy.pickConnection(RandomBalanceStrategy.java:75)
    com.mysql.jdbc.LoadBalancingConnectionProxy.pickNewConnection(LoadBalancingConnectionProxy.java:711)
    com.mysql.jdbc.LoadBalancingConnectionProxy.dealWithInvocationException(LoadBalancingConnectionProxy.java:415)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:654)
    com.mysql.jdbc.LoadBalancingConnectionProxy.invoke(LoadBalancingConnectionProxy.java:549)
    $Proxy22.ping(Unknown Source)
    com.mysql.jdbc.ReplicationConnection.ping(ReplicationConnection.java:986)
    sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    com.mchange.v2.c3p0.impl.NewProxyConnection.rawConnectionOperation(NewProxyConnection.java:1315)
    com.mysql.jdbc.integration.c3p0.MysqlConnectionTester.activeCheckConnection(MysqlConnectionTester.java:78)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.testPooledConnection(C3P0PooledConnectionPool.java:368)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.refurbishResourceOnCheckin(C3P0PooledConnectionPool.java:301)
    com.mchange.v2.resourcepool.BasicResourcePool.attemptRefurbishResourceOnCheckin(BasicResourcePool.java:1606)
    com.mchange.v2.resourcepool.BasicResourcePool.access$200(BasicResourcePool.java:32)
    com.mchange.v2.resourcepool.BasicResourcePool$1RefurbishCheckinResourceTask.run(BasicResourcePool.java:1228)
    com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

如果我遗漏了什么请纠正我..
谢谢，
帕里玛

最佳答案

所以，发生的事情很清楚:c3p0 正在测试 checkin 时的连接。这些测试挂起，既不成功也不因异常而失败，最终使线程池饱和并陷入死锁。

我无法确定回答的问题是为什么连接测试挂起。从堆栈跟踪中可以清楚地看出，他们试图做的是重新连接，这正是您希望发生的情况，但连接到您的复制(从属)服务器。相反，重新连接失败，并且线程正在休眠。查看mysql的ConnectionImpl类的源代码，connectWithRetry会休眠initialTimout秒(默认2)并重试直到maxReconnects时间(默认3)。默认情况下，这意味着事情最多只能挂起 6 秒。不过，看起来您遇到的挂起时间可能比这更长。

一种解决方法是设置 autoReconnect=false。然后连接测试可能会失败，c3p0 将尝试获取新的连接，这有望从故障转移服务器成功。

其他可以尝试的事情是减少initialTimeout和maxConnects以使失败更快。同样，如果内部重新连接失败，c3p0 将重新获取失效连接，该连接现在应该指向故障转移服务器。

最终，这里有一些未知数:(1) 您的连接应该重新连接的复制服务器是否处于事件状态并已启动并正在运行？因为明显的问题是 mysql 驱动程序在失败时无法建立新的连接，真正的问题是为什么 com.mysql.jdbc.ReplicationDriver 的行为不符合广告，并连接到备用服务器。一种可能性是替代服务器存在问题。请验证您是否可以直接连接到该 [ jdbc:mysql://192.168.102.23/hhmefep ]。如果没有，那是你的问题! (2) 如果可以连接到替代服务器，我们仍然不知道 connectWithRetries(...) 之前的故障转移逻辑是否真正起作用，即是否正在尝试连接到复制服务器？ (可能值得做的一件事是有意关闭复制的服务器，这样就没有什么可以进行故障转移。应用程序是否会更干净地失败？)

我想，作为一个实际问题，我会验证复制服务器是否正常工作，减少 initialTimout and maxReconnects (也许是 1 和 1)，然后重试。如果这不起作用，我会将 autoReconnect 设置为 false。如果您确实将 autoReconnect 设置为 false，则可以使用 c3p0 参数 maxConnectionAge 来确保当主服务器恢复时，连接(相当)立即被返回到主服务器的连接替换。将 maxCoonnectionAge 设置为几分钟(而不是几秒，否则您将搅动连接并降低性能)。

祝你好运!

关于mysql - 如何使用 c3p0 进行节点故障转移测试，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23264122/

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