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https://issues.apache.org/jira/browse/WICKET-625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12505787
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Alastair Maw commented on WICKET-625:
-------------------------------------

I've now put in a bunch of fixes for this, such that we're probably 80% of the 
way there. This is the easy 80%, mind you. ;-)
The remaining things are harder to fix, as they mostly references Methods not 
classes.

> Wicket doesn't clean up properly when hot-deploying; hangs onto Class 
> references.
> ---------------------------------------------------------------------------------
>
>                 Key: WICKET-625
>                 URL: https://issues.apache.org/jira/browse/WICKET-625
>             Project: Wicket
>          Issue Type: Bug
>          Components: wicket, wicket-extensions, wicket-spring
>    Affects Versions: 1.3.0-beta1
>            Reporter: Alastair Maw
>            Assignee: Alastair Maw
>         Attachments: WICKET-625.patch
>
>
> When you undeploy a webapp, ideally it should go away and its 
> WebAppClassLoader should be garbage collected. There are various reasons this 
> won't happen, but they essentially split into two problems:
> 1) The App Server has references to classes in the WebAppClassLoader in its 
> own objects (on Tomcat these are typically commons logging statics in 
> StandardContext in catalina, or some of the jakarta code). There's not much 
> you can do about this, short of getting a better app server.
> 2) You hold references to Class objects loaded by your WebAppClassLoader in 
> static fields in other Classes loaded by your WebAppClassLoader.
> Number 2 can be solved by the use of WeakReferences to the Class objects.
> Note that you also need to be careful about classes that have Class 
> references internally, such as java.lang.reflect.Method and Field. You can 
> also hold these items in a WeakReference, but they have the potential to be 
> garbage collected randomly, unlike the underlying Class objects.
> I have some patches that allow me to start up and shut down a Spring-backed 
> Wicket-based app and have the classloader cope properly. They could probably 
> do with some review.

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