我一直在努力让我的Web应用程序停止抛出破坏的管道/超时异常。我读过很多帖子（here，here，here，here和其他人）和blogs，但无济于事。
我的c3p0-0.9.1.2.jar, hibernate-c3p0-4.1.1.Final.jar, hibernate-core-4.1.1.Final.jar文件夹中有WEB-INF/lib和所有必需的jar文件。我不认为版本是问题，但我想，我应该列出细节。 Apache Tomcat/6.0.24，MySQL Ver 14.14 Distrib 5.1.70。所有这些都在Ubuntu 10.04.4 LTS，lucid上运行。
在（db）不活动8小时后，我的catalina日志中出现以下异常：
10:18:45,657 WARN SqlExceptionHelper:143 - SQL Error: 0, SQLState: 08S01
10:18:45,660 ERROR SqlExceptionHelper:144 - The last packet successfully received from the server was 69,956,254 milliseconds ago. The last packet sent successfully to the server was 69,956,255 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
org.hibernate.exception.JDBCConnectionException: The last packet successfully received from the server was 69,956,254 milliseconds ago. The last packet sent successfully to the server was 69,956,255 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:131)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:129)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at sun.proxy.$Proxy24.executeQuery(Unknown Source)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1962)
at org.hibernate.loader.Loader.doQuery(Loader.java:829)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:289)
at org.hibernate.loader.Loader.doList(Loader.java:2447)
at org.hibernate.loader.Loader.doList(Loader.java:2433)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2263)
at org.hibernate.loader.Loader.list(Loader.java:2258)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:470)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1161)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at gr.adds.myapp.server.db.DB.getBFromUser(DB.java:49)
at gr.adds.myapp.server.BSImpl.getBusesInfo(BSImpl.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:891)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:679)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 69,956,254 milliseconds ago. The last packet sent successfully to the server was 69,956,255 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3364)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1983)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2293)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at sun.reflect.GeneratedMethodAccessor37.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:122)
... 41 more
Caused by: java.net.SocketException: Broken pipe
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3345)
... 51 more
这是我的hibernate.cfg.xml：
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/mydb?autoReconnect=true</property>
<property name="connection.username">dbuser</property>
<property name="connection.password">dbpass</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">false</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hibernate.hbm2ddl.auto">update</property>
<property name="hibernate.connection.useUnicode">true</property>
<property name="hibernate.connection.characterEncoding">UTF-8</property>
<!-- hibernate.cfg.xml -->
<property name="connection.autoReconnect">true</property>
<property name="connection.autoReconnectForPools">true</property>
<property name="connection.is-connection-validation-required">true</property>
<property name="current_session_context_class">thread</property>
<!-- <property name="max_fetch_depth">1</property> -->
<property name="hibernate.connection.provider_class">org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider</property>
<!-- <property name="hibernate.c3p0.initial_size">5</property> -->
<!-- <property name="hibernate.c3p0.min_size">5</property> -->
<!-- <property name="hibernate.c3p0.max_size">50</property> -->
<!-- <property name="hibernate.c3p0.timeout">1800</property> -->
<!-- <property name="hibernate.c3p0.max_statements">250</property> -->
<!-- <property name="hibernate.c3p0.idle_test_period">60</property> -->
<!-- <property name="hibernate.c3p0.acquire_increment">5</property> -->
<property name="hibernate.c3p0.numHelperThreads">3</property>
<!-- no "connection.pool_size" entry! -->
<!-- JDBC connection pool (use the built-in) -->
<!-- <property name="connection.pool_size">1</property> -->
<!-- <property name="hibernate.transaction.auto_close_session">false</property> -->
<property name="hibernate.c3p0.acquire_increment">3</property>
<property name="hibernate.c3p0.idle_test_period">25200</property>
<property name="hibernate.c3p0.timeout">1800</property>
<property name="hibernate.c3p0.max_size">15</property>
<property name="hibernate.c3p0.min_size">3</property>
<property name="hibernate.c3p0.max_statements">250</property>
<property name="hibernate.c3p0.preferredTestQuery">SELECT 1;</property>
<property name="hibernate.c3p0.testConnectionOnCheckout">true</property>
<!-- Mapping files -->
...
</session-factory>
另外，我在与c3p0.properties相同的文件夹中有hibernate.cfg.xml个文件：
c3p0.testConnectionOnCheckout=true
c3p0.preferredTestQuery=SELECT 1;
com.mchange.v2.c3p0.management.ManagementCoordinator=com.mchange.v2.c3p0.management.NullManagementCoordinator
我的tomcat tomcat6/conf/server.xml文件有：
<Connector port="8080" protocol="AJP/1.3" connectionTimeout="20000" URIEncoding="UTF-8" redirectPort="8443" />
我的/etc/mysql/my.conf文件是默认文件。
我应该告诉你我尝试了很多种组合。
首先，在wait_timeout中添加/etc/mysql/my.conf似乎没有任何效果（UPDATED-＆gt; READ UPDATE BELOW）。我把它改为60（60秒），等了几分钟，没有得到我期待的例外。我把这个值放在那里已经等了8个小时，但我相信结果会是一样的。没有wait_timeout属性，8小时后我每次都会得到类似的例外情况（只有时差）。
我读过hibernate.c3p0.idle_test_period应该小于mys wait_timeout，这就是为什么我第一次有7小时（25200秒），而后者默认为8小时。我也玩过其他的值，但它们似乎并不重要。您在我上面的hibernate.cfg.xml文件中看到了几个注释掉的值，因为我尝试了很多种组合。我已经读到testConnectionOnCheckout价格昂贵，但我添加了它以确定我是否可以完成这项工作。
当然，重启tomcat（sudo service tomcat6 restart）有效，但这不是解决方案。
有没有人知道我可以尝试/改变什么让这个停止给我这个例外？任何“神奇”的价值观会使它发挥作用吗？
更新
好的，我没有把wait_timout放在[mysqld]里面。 所以我放入了my.conf
wait_timeout=120
并在hibernate.cfg.xml中：
<property name="hibernate.c3p0.idle_test_period">80</property>
<property name="hibernate.c3p0.timeout">60</property>
现在我得到的错误是：
14:15:41,746 WARN NewPooledConnection:486 - [c3p0] A PooledConnection that has already signalled a Connection error is still in use!
14:15:41,747 WARN NewPooledConnection:487 - [c3p0] Another error has occurred [ com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed. ] which will not be reported to listeners!
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1205)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1197)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4186)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4152)
at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask.run(GooGooStatementCache.java:525)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 300,078 milliseconds ago. The last packet sent successfully to the server was 18 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3102)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2991)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3532)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2293)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at sun.reflect.GeneratedMethodAccessor37.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.hibernate.engine.jdbc.internal.proxy.AbstractStatementProxyHandler.continueInvocation(AbstractStatementProxyHandler.java:122)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at sun.proxy.$Proxy24.executeQuery(Unknown Source)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1962)
at org.hibernate.loader.Loader.doQuery(Loader.java:829)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:289)
at org.hibernate.loader.Loader.doList(Loader.java:2447)
at org.hibernate.loader.Loader.doList(Loader.java:2433)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2263)
at org.hibernate.loader.Loader.list(Loader.java:2258)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:470)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1161)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at gr.adds.myapp.server.db.DB.getBFromUser(DB.java:49)
at gr.adds.myapp.server.BSImpl.getBusesInfo(BSImpl.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:891)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2552)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3002)
... 53 more
14:15:41,751 WARN SqlExceptionHelper:143 - SQL Error: 0, SQLState: 08003
14:15:41,752 ERROR SqlExceptionHelper:144 - No operations allowed after connection closed.
org.hibernate.exception.JDBCConnectionException: No operations allowed after connection closed.
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:68)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.proxy.ConnectionProxyHandler.continueInvocation(ConnectionProxyHandler.java:146)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at sun.proxy.$Proxy23.prepareStatement(Unknown Source)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:147)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:166)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:145)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1720)
at org.hibernate.loader.Loader.doQuery(Loader.java:828)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:289)
at org.hibernate.loader.Loader.doList(Loader.java:2447)
at org.hibernate.loader.Loader.doList(Loader.java:2433)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2263)
at org.hibernate.loader.Loader.list(Loader.java:2258)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:470)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1161)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at gr.adds.myapp.server.db.DB.getBFromUser(DB.java:49)
at gr.adds.myapp.server.BSImpl.getBusesInfo(BSImpl.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:891)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Thread.java:679)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1205)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1197)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4186)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4152)
at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.mchange.v2.c3p0.stmt.GooGooStatementCache$1StmtAcquireTask.run(GooGooStatementCache.java:525)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
有什么想法吗？不应该是wait_timeout > c3p0.idle_test_period > c3p0.timeout？
10月7日更新：
仍然是相同的超时，但我在我的log4j.properties文件中添加了日志信息，以确保c3p0在我的hibernate.cfg.xml文件中运行了所需的值，并且我确实得到了：
11:13:09,393 INFO MLog:92 - MLog clients using log4j logging.
11:13:09,477 INFO C3P0Registry:216 - Initializing c3p0-0.9.2.1 [built 20-March-2013 11:16:28 +0000; debug? true; trace: 10]
11:13:09,627 INFO AbstractPoolBackedDataSource:522 - Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@3d0991ef [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@b336cd6b [ acquireIncrement -> 1, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> false, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> z8kflt8x14i4fy2kk9fga|7eac4d3b, idleConnectionTestPeriod -> 60, initialPoolSize -> 3, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 120, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 25, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 1, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource@ebdc296f [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> z8kflt8x14i4fy2kk9fga|1fbbc779, jdbcUrl -> jdbc:mysql://localhost:3306/mydb?autoReconnect=true, properties -> {autoReconnect=true, is-connection-validation-required=true, useUnicode=true, user=******, password=******, characterEncoding=UTF-8, autoReconnectForPools=true} ], preferredTestQuery -> select 1;, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> z8kflt8x14i4fy2kk9fga|27b104d7, numHelperThreads -> 3 ]
同样更新到最新的库以防万一，但仍然相同：c3p0-0.9.2.1.jar, hibernate-c3p0-4.2.6.Final.jar, hibernate-commons-annotations-4.0.2.Final.jar, hibernate-core-4.2.6.Final.jar, mysql-connector-java-5.1.26-bin.jar。
答案 0 :(得分：0)
这种事情几乎总是由防火墙或其他一些网络组件关闭空闲连接引起的。解决方案是使用连接测试语句，看起来就像你正在做的那样。我对C3P0一无所知（除了它还没有发布1.0），所以我无法判断你的配置是否正确以防止空闲超时。
我想知道你为什么不使用Tomcat的内置连接池。它似乎完美无缺，配置正常。