Re: [Springframework-developer] CGLIB memory usage within class loader

[Guillaume P. <gpo...@gl...>]

> I only wish A) there was a way to explicitly blow away the classloader
> or B) have hibernate be redeployable.  One option is to place all the
> Hibernate related classes inside Tomcat's shared Classloader.  This
> might reduce the amount of times I need to restart.

Well, if you care enough, I'm pretty sure you could create a ContextListener
that would cleanup when the context is destroyed.  It would invole 
reflection
to hack in private fields of the Threads though, so the solution might fail
in different JVM, and wouldn't work well with SecurityManagers. Basically,
what you would have to do is to get the list of all the system's thread 
(through
ThreadGroup), and for each of them, iterate the "threadLocals" map, and
the "inheritableThreadLocals", to cleanup any instance for which the
ClassLoader is the current webapp or of child of it.

You might also have to cleanup a few other things though, such as if you 
have
any JDBC drivers in your webapp's ClassLoader, they need to be explicitly
unregistered, otherwise they will not be garbage collected.

I create a prototype of a ContextListener that does that if you want.

Guillaume

----- Original Message ----- 
From: "Seth Ladd" <set...@gm...>
To: <spr...@li...>
Sent: Wednesday, October 20, 2004 2:26 PM
Subject: Re: [Springframework-developer] CGLIB memory usage within class 
loader


> On Tue, 19 Oct 2004 22:10:20 -0400, Guillaume Poirier
> <gpo...@gl...> wrote:
>> > How does it not create a leak if the classloader is not going away?
>> > The real cause of the OOM exceptions is that the WebappClassLoader
>> > instances never go away.
>>
>> I meant if the container (e.g. Tomcat) doesn't throw the ClassLoader 
>> away,
>> i.e. if it's still in use...
>> Of course, if the webapp is reloaded and the old ClassLoader isn't
>> collected, that's a leak.
>>
>> What I was saying is the problem with Dom4j cause a leak when you reload 
>> the
>> webapp,
>> but cause no leak if you never use hot-reload.  (While the CGLIB leak
>> apparently does the opposite)
>
> Ahh... that's what I thought.  Thanks for the clarification!
>
> I only wish A) there was a way to explicitly blow away the classloader
> or B) have hibernate be redeployable.  One option is to place all the
> Hibernate related classes inside Tomcat's shared Classloader.  This
> might reduce the amount of times I need to restart.
>
> Seth
>
>
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