[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-7020) Connection leak with nested sessions

[Zoltán Holub (JIRA)]

     [ https://hibernate.onjira.com/browse/HHH-7020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zoltán Holub updated HHH-7020:
------------------------------

    Attachment: HHH-7020.diff

I've made a patch for this issue.
The org/hibernate/engine/jdbc/internal/JdbcResourceRegistryImpl.java class contains some old commented out code, where exceptions are handled correctly.
I introduced the same exception handling in the new code, and it seems it fixed the problem.


> Connection leak with nested sessions
> ------------------------------------
>
>                 Key: HHH-7020
>                 URL: https://hibernate.onjira.com/browse/HHH-7020
>             Project: Hibernate ORM
>          Issue Type: Bug
>          Components: core, entity-manager
>    Affects Versions: 4.0.0.Final, 4.0.1, 4.1.0
>         Environment: Windows 7.
> Java 1.6.0_25, Java 1.7.0
>            Reporter: Zoltán Holub
>         Attachments: HHH-7020.diff, testcase-connectionleak.zip
>
>
> I'am using a Hibernate interceptor to track data modifications. In the interceptor's onFlushDirty() method, i open a new session without interceptors using the same JDBC connection. 
> After closing this nested session and the original entitymanager, the JDBC connection doesn't released.
> I could reproduce this problem outside any interceptor. I have made a junit test without interceptors which shows the same problem.
> I have found that Hibernate throws and catches a HibernateException with message "proxy handle is no longer valid". This exception is logged on debug level.
> I investigated that the problem is in the following code:
> LogicalConnectionImpl.java
> 	public Connection close() {
> 		LOG.trace( "Closing logical connection" );
> 		Connection c = isUserSuppliedConnection ? physicalConnection : null;
> 		try {
> 			releaseProxies();
> 			jdbcResourceRegistry.close();
> 			if ( !isUserSuppliedConnection && physicalConnection != null ) {
> 				releaseConnection();
> 			}
> 			return c;
> 		}
> 		finally {
> 			// no matter what
> 			physicalConnection = null;
> 			isClosed = true;
> 			LOG.trace( "Logical connection closed" );
> 			for ( ConnectionObserver observer : observers ) {
> 				observer.logicalConnectionClosed();
> 			}
> 			observers.clear();
> 		}
> 	}
> The invocation of jdbcResourceRegistry.close() throws this exception, and this is why it skips the following releaseConnection(). The condition of IF statement is true.
> This code is new to Hibernate 4. I have tried 4.0.0, 4.0.1 and 4.1.0-SNAPSHOT and all of them has the problem. Hibernate 3.6.0 is not affected.
> My JUnit test could run with Hibernate 3.x with minor changes. (3.x code also in the JUnit test)
> I have tried different ways to work around the problem. The only way it worked is to use a simple doWork() and native JDBC operations. This test case also in the unit test.

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