我有一个通过 Hibernate 使用 MySQL 和 c3p0 的网络应用程序。通常一切都运行良好，但是当 MySQL 达到它的 interactive_timeout 并且我尝试另一个查询时，出现了:
WARN [SqlExceptionHelper] - SQL Error: 0, SQLState: 08S01
ERROR [SqlExceptionHelper] - Communications link failure
Last packet sent to the server was 1 ms ago.
[ERROR] c.l.w.p.resources.AdminResource - Cannot pull data from remote server
javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: could not extract ResultSet
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387) ~[hibernate-entitymanager-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1310) ~[hibernate-entitymanager-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:277) ~[hibernate-entitymanager-4.2.7.Final.jar:4.2.7.Final]
at com.logicdrop.wam.services.ClassroomService.findSessions(ClassroomService.java:159) ~[com.logicdrop.wam.shared-1.1.6-SNAPSHOT.jar:1.1.6-SNAPSHOT]
at com.logicdrop.wam.portal.resources.AdminResource.getSessions(AdminResource.java:51) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_40]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_40]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_40]
at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_40]
at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1511) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1442) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1391) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1381) [jersey-server-1.17.1.jar:1.17.1]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416) [jersey-servlet-1.17.1.jar:1.17.1]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:538) [jersey-servlet-1.17.1.jar:1.17.1]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:716) [jersey-servlet-1.17.1.jar:1.17.1]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) [javax.servlet-3.0.0.v201112011016.jar:na]
at com.google.inject.servlet.ServletDefinition.doService(ServletDefinition.java:263) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.ServletDefinition.service(ServletDefinition.java:178) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.ManagedServletPipeline.service(ManagedServletPipeline.java:91) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:62) [guice-servlet-3.0.jar:na]
at com.logicdrop.wam.web.CorsFilter.doFilter(CorsFilter.java:59) [com.logicdrop.wam.shared-1.1.6-SNAPSHOT.jar:1.1.6-SNAPSHOT]
at com.google.inject.servlet.FilterDefinition.doFilter(FilterDefinition.java:163) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:58) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:118) [guice-servlet-3.0.jar:na]
at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:113) [guice-servlet-3.0.jar:na]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1419) [jetty-servlet-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:455) [jetty-servlet-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557) [jetty-security-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1075) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:384) [jetty-servlet-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1009) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.Server.handle(Server.java:370) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:949) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1011) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644) [jetty-http-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235) [jetty-http-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82) [jetty-server-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668) [jetty-io-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52) [jetty-io-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608) [jetty-util-8.1.11.v20130520.jar:8.1.11.v20130520]
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543) [jetty-util-8.1.11.v20130520.jar:8.1.11.v20130520]
at java.lang.Thread.run(Thread.java:724) [na:1.7.0_40]
Caused by: org.hibernate.exception.JDBCConnectionException: could not extract ResultSet
at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:132) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:61) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.getResultSet(Loader.java:2040) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1837) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1816) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.doQuery(Loader.java:900) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:342) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2526) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2512) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2342) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.Loader.list(Loader.java:2337) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:495) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:357) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1275) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:268) ~[hibernate-entitymanager-4.2.7.Final.jar:4.2.7.Final]
... 56 common frames omitted
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 3 ms ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.7.0_40]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[na:1.7.0_40]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.7.0_40]
at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[na:1.7.0_40]
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2985) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1885) ~[mysql-connector-java-5.1.6.jar:na]
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:116) ~[c3p0-0.9.2.1.jar:0.9.2.1]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:56) ~[hibernate-core-4.2.7.Final.jar:4.2.7.Final]
... 71 common frames omitted
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:2431) ~[mysql-connector-java-5.1.6.jar:na]
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2882) ~[mysql-connector-java-5.1.6.jar:na]
... 80 common frames omitted
这是我目前拥有的 c3p0 设置:
<property name="hibernate.connection.provider_class" value="org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider" />
<property name="hibernate.c3p0.acquire_increment" value="2" />
<property name="hibernate.c3p0.max_statements" value="0" />
<property name="hibernate.c3p0.min_size" value="5" />
<property name="hibernate.c3p0.max_size" value="25" />
<property name="hibernate.c3p0.timeout" value="0" />
<property name="hibernate.c3p0.validate" value="true" />
<property name="hibernate.c3p0.idle_test_period" value="5" />
<property name="hibernate.c3p0.preferred_test_query" value="SELECT 1;" />
我很确定我需要更改这些设置中的某些内容，但我不太确定。任何人都可以阐明这里发生的事情吗？
谢谢， 泰勒
最佳答案
我知道发生了什么事。 MySQL 超时，但 c3p0 无法识别它何时发生，因此我们必须在 MySQL 超时之前重新启动池连接。
- 首先，我在我的类路径中创建了一个名为
c3p0-config.xml的新文件，我可以在其中放置我所有的 c3p0 设置。我不知道这是否真的有帮助，但我还是想将 c3p0 与 hibernate 分离。 然后，我将其放入新的配置文件中:
<c3p0-config> <default-config> <property name="acquireIncrement">3</property> <property name="idleConnectionTestPeriod">5</property> <property name="maxConnectionAge">30</property> <property name="maxIdleTime">10</property> <property name="maxPoolSize">25</property> <property name="maxStatements">0</property> <property name="minPoolSize">5</property> <property name="preferredTestQuery">SELECT 1</property> <property name="testConnectionOnCheckin">true</property> <property name="testConnectionOnCheckout">true</property> </default-config> </c3p0-config>
最重要的是 maxConnectionAge 和 maxIdleTime，它们丢弃了这么多秒的连接。可以找到所有变量的描述 here .
这并不能解决我项目中的所有问题，但至少修复了这个错误。
关于java - hibernate/C3P0 : Server crashes after MySQL timeout，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20075577/