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https://issues.apache.org/jira/browse/OPENJPA-2454?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Cedric Tabin updated OPENJPA-2454:
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Comment: was deleted
(was: Simple project showing how to trigger a memory leak.
Further explanations in the README.)
> Memory leak when using multiple classloaders
> --------------------------------------------
>
> Key: OPENJPA-2454
> URL: https://issues.apache.org/jira/browse/OPENJPA-2454
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 2.2.2
> Environment: Java EE6 with Glassfish 3.1.2.2, MySQL 5.1, VisualVM
> 1.3.6, Linux Gentoo
> Reporter: Cedric Tabin
> Priority: Minor
> Attachments: classloader-leak-ee.zip
>
>
> Hello,
> When entities are retrieved from a class loaded dynamically (ie by a [new]
> ClassLoader), OpenJPA will trigger a memory leak that will prevent the JVM to
> GC the loaded classes.
> An simple example can be easily reproduced and is attached to the ticket.
> Further explanations are provided in the README.
> The main steps are the following:
> 1) When a query comes, create a new ClassLoader (see
> ch.astorm.ejb.facade.EntryPointBean and
> ch.astorm.ejb.system.ClassLoaderManager)
> 2) Load dynamically a new instance of a class in the ClassLoader of step (1).
> This class should not be included in the EJB (see
> ch.astorm.apis.SimpleProcessor).
> 3) Invoke a method on it that will retrieve some data, using JPA (a
> getResultList) injecting the arguments directly in the query string (not
> using the Query.setParameter method).
> In the sample project provided, there are 8 queries asking for one instance
> of Person each. The class asked to do this job is
> ch.astorm.apis.SimpleProcessor which extends
> ch.astorm.ejb.system.AbstractProcessor (actually doing the job).
> One over two of thoses requests asks to reset the classloader (ie to drop all
> the current loaded classes and create a new one).
> After thoses requests, if one looks in a heap dump, he will see 4 instances
> of MyClassLoader (which is an internal class of
> ch.astorm.ejb.system.ClassLoaderManager). Of course there should be only one
> instance of the latter...
> What is surprisingly weird is that 3 of those instances have no GC root,
> meaning they *should* be collected but actually never will, even if the
> PermGen space is full.
> It looks like a bug in the JVM, but if the JPA implementation is changed to
> EclipseLink in the persistence.xml, then there is no more leak. That drives
> me to say that OpenJPA could make something the JVM doesn't like...
> The problem arises on Linux/Windows, Glassfish-3.1.2.2/Weblogic-12c,
> MySQL/Oracle.
> Thansk for your help !
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