c3p0连接管理问题

Question

我使用Spring 3.0.2，Hibernate 3.5.0和c3p0 0.9.1.2，并且在检索连接和提交事务时出现大量错误。这里是我的C3P0的配置：

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> 
    <property name="driverClass" value="${jdbc.driverClassName}"/> 
    <property name="jdbcUrl" value="${jdbc.url}"/> 
    <property name="properties"> 
     <props> 
      <prop key="c3p0.acquireIncrement">5</prop> 
      <prop key="c3p0.maxIdleTime">30</prop> 
      <prop key="c3p0.idleConnectionTestPeriod">20</prop> 
      <prop key="c3p0.maxPoolSize">100</prop> 
      <prop key="c3p0.maxStatements">0</prop> 
      <prop key="c3p0.minPoolSize">1</prop> 
      <prop key="user">${jdbc.username}</prop> 
      <prop key="password">${jdbc.password}</prop> 
     </props> 
    </property> 
</bean> 

直到最近，我得到这个错误非常频繁：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
Last packet sent to the server was 0 ms ago. 

最近我也得到这些：

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Connection.close() has already been called. Invalid operation in this state. 
java.sql.SQLException: Connections could not be acquired from the underlying database! 

有什么建议？

Answer 1

这可能是因为连接超时。检出idle_test_period设置或使用bonecp http://jolbox.com，它具有合理的默认值。