[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-6891) Hibernate is not reusing connections from the pool

[Joseph Carneiro (JIRA)]

    [ https://hibernate.onjira.com/browse/HHH-6891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=45750#comment-45750 ] 

Joseph Carneiro commented on HHH-6891:
--------------------------------------

I'm experiencing a similar issue.

Environment:

Spring 3.1.1
Web Flow 2.3.0
Hibernate 4.1.0
c3p0 0.9.1.2

Problem:

When I make any calls to the EntityManager in a Spring Web Flow the connections are never closed. I've turned on c3p0 logging and it shows that the pool grows every time I start a flow. This is a real problem as the pool is exhausted and the application hangs. Reaching the end-state doesn't release the connections. I have service calls within the flow that use the EntityManager and c3p0's debug traces indicate these are the culprits. I've tried calling close on the EntityManager after completing the queries, but this has no effect. I have several standard Spring Controllers in my application as well; they make use of the EntityManager through the same service calls and the connections are closed. Only the flows are keeping the connections open. I'm using <persistence-context/> in the flows and my EntityManager is annotated with @PersistenceContext.

> Hibernate is not reusing connections from the pool
> --------------------------------------------------
>
>                 Key: HHH-6891
>                 URL: https://hibernate.onjira.com/browse/HHH-6891
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 4.0.0.CR7
>         Environment: Hibernate 4, MySQL 5.6
>            Reporter: Mat Banik
>              Labels: c3p0, dbcp, hibernate
>
> I have tried two connection pool providers C3P0 and Commons DBCP. Both are the most current versions. 
> Everything starts fine. And data is loading from database as expected.
> But with C3P0 when left to defaults everything stops when maximum of 15 connections are reached. Nothing is freed up and the application behaves like it has memory leak.
> Here is bottom of log output
> 2011-12-13/17:21:55.167/EST [http-bio-80-exec-2] DEBUG begin
> 2011-12-13/17:21:55.167/EST [http-bio-80-exec-2] DEBUG Obtaining JDBC connection
> 2011-12-13/17:21:55.167/EST [http-bio-80-exec-2] DEBUG acquire test -- pool is already maxed out. [managed: 15; max: 15]
> 2011-12-13/17:21:55.167/EST [http-bio-80-exec-2] DEBUG awaitAvailable(): com.mchange.v2.c3p0.impl.NewPooledConnection at 46f0decc
> 2011-12-13/17:21:55.167/EST [http-bio-80-exec-2] DEBUG trace com.mchange.v2.resourcepool.BasicResourcePool at 9671641 [managed: 15, unused: 0, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection at 46f0decc)
> With Commons DBCP everything work as well until when maximum connections are reached and than it throws exception:
> org.springframework.orm.hibernate4.HibernateJdbcException: JDBC exception on Hibernate data access: SQLException for SQL [n/a]; SQL state [null]; error code [0]; Could not open connection; nested exception is org.hibernate.exception.GenericJDBCException: Could not open connection org.springframework.orm.hibernate4.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:165) org.springframework.orm.hibernate4.HibernateExceptionTranslator.convertHibernateAccessException(HibernateExceptionTranslator.java:50) org.springframework.orm.hibernate4.HibernateExceptionTranslator.translateExceptionIfPossible(HibernateExceptionTranslator.java:37) org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:58) org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213) org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:163) org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) 

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