[hibernate-issues] [Hibernate-JIRA] Issue Comment Edited: (HHH-5601) Memory leak when building session factory from xml, classloader does not get garbage-collected

[Juan Alvarez Gimenez (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-5601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=38541#action_38541 ] 

Juan Alvarez Gimenez edited comment on HHH-5601 at 9/28/10 10:00 PM:
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One more thing I forgot to tell. To build the webapp, maven2 is needed and any JDBC database connection (I use oracle-xe)

      was (Author: juan.alvarez):
    One more thing I forgot to tell. To run the webapp, maven2 is needed and any JDBC database connection (Here I use oracle-xe)
  
> Memory leak when building session factory from xml, classloader does not get garbage-collected
> ----------------------------------------------------------------------------------------------
>
>                 Key: HHH-5601
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5601
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.3.2, 3.5.1
>         Environment: linux, jdk 5 and 6, apache tomcat 5.5.x to 7.0
>            Reporter: Juan Alvarez Gimenez
>         Attachments: leakwebapp.zip
>
>
> Hello.
> I was able to create a minimum web-application which fails to be garbage collected if session factory uses xml configuration file. This does not happens when it is created programmatically.
> The big issue is that in production environment this problem leads to a OutOfMemoryException because of PermGen (because it is needed to restart the context from time to time)
> When building session factory from xml, and after starting and then stopping context, I can see all the classes from the webapp using any profiler (jvisualvm, eclipse's memory analyzer, etc). But I could not figure out if the problem is due to how hibernate uses Dom4J or if it is a Dom4J problem. I also switched to many different version of Dom4J but problem still remains.
> Here I provide a minimal web application which has only 1 (one) class that creates an empty session factory (this class is a ServletContextListener and is named  FDVContextListener) with only a database connection. No mappings at all. The experiment consists in start a Tomcat (maybe 6.0.25+ or 7.x which has the memory leak feature) and later stop the context. Finally, check for leak you'll find webapps classes still there.
> 2nd part of the experiment is to modify the listener to make it use the programmatic session factory (already provided) and then repeat the start-stop of the context and the memory leak test and confirm that webapp is completly gone.
> I repeat again. I'm not sure if it is a Dom4J problem or an Hibernate problem, but I think this is a great opportunity (because of the small test-application) to help find the real problem since hibernate get's affected.
> Hope we can find a solution to this problem.
> thank you all.
> Juan Manuel

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