java - c3p0 getConnection() 抛出异常 : A ResourcePool could not acquire a resource from its primary factory or source

Question

我们的项目有一个 [Hibernate + c3p0 + MySQL] 配置。我们遇到了以下异常:

com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
    at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525) ~[c3p0-0.9.1.2.jar:0.9.1.2]
Wrapped by: java.sql.SQLException: Connections could not be acquired from the underlying database!
    at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128) ~[c3p0-0.9.1.2.jar:0.9.1.2]
    at org.hibernate.service.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:141) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:276) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:297) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
Wrapped by: org.hibernate.exception.GenericJDBCException: Could not open connection
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:52) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:304) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:169) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:67) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1263) ~[hibernate-core-4.0.1.Final.jar:4.0.1.Final]
    at org.springframework.orm.hibernate4.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:399) ~[spring-orm-3.1.2.RELEASE.jar:3.1.2.RELEASE]
Wrapped by: org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Could not open connection
    at org.springframework.orm.hibernate4.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:440) ~[spring-orm-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371) ~[spring-tx-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:336) ~[spring-tx-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105) ~[spring-tx-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) ~[spring-aop-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) ~[spring-aop-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at $Proxy28.messageExists(Unknown Source) ~[na:na]

我们的 c3p0 配置:

<bean id="provDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
…
        <property name="acquireIncrement" value="1" />
        <property name="idleConnectionTestPeriod" value="100"/>
        <property name="minPoolSize" value="5" />
        <property name="maxPoolSize" value="50" />
        <property name="maxIdleTime" value="1800" />
</bean>

请注意，我们还在这个 MySQL 实例之上配置了另一个类似的 c3p0 数据源。

谁能给我一些关于如何调试它的建议？

Answer 1

虽然没有严格回答你的问题，但我不想在评论中添加代码，因为评论中的代码不可读。

这是我项目中带有 C3P0 的 MySQL 配置示例。请注意所有额外参数以确保连接不会中断。 (最后我选择了 Postgres，因为它没有终止我的连接并且总体上更稳定，还必须重新测试与 select 1 的连接；不是很有效)

<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.minPoolSize">0</prop>
        <prop key="hc3p0.maxPoolSize">1000</prop>
        <prop key="hc3p0.timeout">3000</prop>
        <prop key="c3p0.acquire_increment">10</prop>
        <prop key="c3p0.max_statement">50</prop>

        <prop key="hibernate.c3p0.idle_test_period">60</prop>
        <prop key="c3p0.preferredTestQuery">SELECT 1;</prop>
        <prop key="hibernate.c3p0.testConnectionOnCheckout">false</prop>
        <prop key="user">${jdbc.username}</prop>
        <prop key="password">${jdbc.password}</prop>
    </props>
  </property>
</bean>