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

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