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https://issues.apache.org/jira/browse/LOG4J2-819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14131939#comment-14131939
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Costa Theodosiou edited comment on LOG4J2-819 at 9/12/14 7:04 PM:
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Attached is a demo project that can cause the PermGen OutOfMemoryError.

It is a regular Servlet 2.5 + Spring + Hibernate webapp.

To replicate the issue, reload the webapp several times. Monitor the permgen 
memory with Java VisualVM. Once the memory leak manifests itself, the Tomcat 
and the application become unresponsive and permgen error is logged in the 
server logs.


was (Author: costat):
Attached is a demo project that can cause the PermGen OutOfMemoryError.

> PermGen OutOfMemoryError when reloading webapp on Tomcat 6
> ----------------------------------------------------------
>
>                 Key: LOG4J2-819
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-819
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 2.0.2
>         Environment: Tomcat 6
>            Reporter: Costa Theodosiou
>            Priority: Critical
>         Attachments: demo.zip, gg-log4j2-clocks-interrupts.patch, 
> gg-log4j2-clocks-v2.patch
>
>
> When reloading an application 3 or 4 times in Tomcat 6, the application 
> crashes with a "java.lang.OutOfMemoryError: PermGen space" exception.
> After some investigation using the "When all else fails" section of 
> https://wiki.apache.org/tomcat/OutOfMemory in conjunction with Java VisualVM, 
> I have narrowed down the problem to the Thread created within 
> org.apache.logging.log4j.core.util.CoarseCachedClock.
> When a Thread is created, it contains a reference to the classloader that it 
> was created with. In this case, the Thread's contextClassLoader field 
> contains a reference to the WebappClassLoader. When Tomcat attempts to unload 
> the webapp, the Thread still holds onto this reference which prevents 
> WebappClassLoader from being freed.
> Perhaps the Log4jServletContextListener (Log4jWebInitializerImpl) can be made 
> to stop the CoarseCachedClock thread.
> I believe this is not an obvious issue on Tomcat 7 due to 
> https://wiki.apache.org/tomcat/MemoryLeakProtection.



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