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Hibernate - org.hibernate.exception.GenericJDBCException: 无法打开连接。

javahibernateormconnectionc3p0
4

为了解决数据库连接过多和空闲连接问题，我们对配置文件进行了以下更改 -

c3p0.min_size=1
c3p0.max_size=20
c3p0.timeout=1800
c3p0.max_statements=50
connection.release_mode=on_close

在尝试运行应用程序时，我们遇到了以下异常。请说明为什么会发生这种情况以及如何纠正 -

HTTP Status 500 - org.hibernate.exception.GenericJDBCException: Cannot open connection

异常报告类型

message org.hibernate.exception.GenericJDBCException: Cannot open connection

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: org.hibernate.exception.GenericJDBCException: Cannot open connection
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    com.alci.filters.ParamFilter.doFilter(ParamFilter.java:27)
root cause

org.hibernate.exception.GenericJDBCException: Cannot open connection
    org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
    org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
    org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
    org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
    org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
    org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
    org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
    org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1577)
    org.hibernate.loader.Loader.doQuery(Loader.java:696)
    org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
    org.hibernate.loader.Loader.doList(Loader.java:2232)
    org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
    org.hibernate.loader.Loader.list(Loader.java:2124)
    org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401)
    org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
    org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1149)
    org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
    com.alci.common.LoginAction.login(LoginAction.java:127)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
    org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
    org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
    org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
    org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    com.alci.filters.ParamFilter.doFilter(ParamFilter.java:27)
root cause

java.sql.SQLException: Connections could not be acquired from the underlying database!
    com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
    com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
    org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:78)
    org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
    org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
    org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
    org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1577)
    org.hibernate.loader.Loader.doQuery(Loader.java:696)
    org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
    org.hibernate.loader.Loader.doList(Loader.java:2232)
    org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
    org.hibernate.loader.Loader.list(Loader.java:2124)
    org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401)
    org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
    org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1149)
    org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
    com.alci.common.LoginAction.login(LoginAction.java:127)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
    org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
    org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
    org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
    org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    com.alci.filters.ParamFilter.doFilter(ParamFilter.java:27)
root cause

com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
    com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
    com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
    com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
    com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
    com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
    org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:78)
    org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
    org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
    org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
    org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1577)
    org.hibernate.loader.Loader.doQuery(Loader.java:696)
    org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
    org.hibernate.loader.Loader.doList(Loader.java:2232)
    org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
    org.hibernate.loader.Loader.list(Loader.java:2124)
    org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401)
    org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
    org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1149)
    org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
    com.alci.common.LoginAction.login(LoginAction.java:127)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    java.lang.reflect.Method.invoke(Method.java:597)
    org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
    org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
    org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
    org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
    org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
    org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    com.alci.filters.ParamFilter.doFilter(ParamFilter.java:27)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.36 logs.
你能贴出根本原因的完整堆栈跟踪吗？ - A. Agarwal
这是一个共享的Tomcat，因此无法立即访问完整的堆栈跟踪。 - Suvo
2个回答
2

您的数据库连接已用尽。

这意味着两件事：

  1. 由于慢查询，您的事务所花费的时间太长，因此一个连接被保持了太长时间。
  2. 您有非常高的流量需求，无法适应20个连接池大小。

我建议您阅读以下阅读我的SO问题答案。

我不认为这个设置是推荐的：

connection.release_mode=on_close

ON_CLOSE - 本质上是上述遗留行为。Hibernate会话在首次需要执行某些JDBC访问时获取连接，并保留该连接直到会话关闭。

on_close - 表示使用ConnectionReleaseMode.ON_CLOSE。这个设置保留了向后兼容性，但不建议使用它。

尝试使用"auto"代替。

这是一个测试环境，因此流量非常少。另一方面，这个异常出现在登录时，所以我想登录时不会有慢查询的情况。 - Suvo
将C3P0日志级别设置为DEBUG，这样您就可以实际看到有多少连接被请求以及它们被释放的速度。 - Vlad Mihalcea
请检查我的更新回复，我认为你不应该使用connection.release_mode=on_close选项。 - Vlad Mihalcea
假设我有一个大型应用程序，在服务层中使用Spring事务管理器，在DAO层中使用Hibernate会话并且没有关闭。那么在hibernate.cfg.xml文件中加入connection.release_mode=on_close语句，是否会关闭这些未关闭的会话？ - Anish B.
@VladMihalcea 我可以在 Hibernate SessionFactory 中使用这个工具吗？如何使用它？ - Anish B.
如果您阅读了链接的文章，您将会找到您问题的答案。 - Vlad Mihalcea
0

这有时是由于超时引起的。增加超时时间，希望能解决问题。

c3p0.timeout=6000
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