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From "Catalin Grigoroscuta (JIRA)" <axis-...@ws.apache.org>
Subject [jira] Commented: (AXIS-935) Using ThreadLocal Call objects in a servlet memory leak both on client and server side
Date Wed, 16 Mar 2005 13:17:22 GMT
     [ http://issues.apache.org/jira/browse/AXIS-935?page=comments#action_60971 ]
     
Catalin Grigoroscuta commented on AXIS-935:
-------------------------------------------

I confirm this bug in axis 1.1.
It appears when you have axis in a web app, in WEB-INF/lib. 
Axis puts some some of its classes on thread locals (Tomcat's threads), which prevents the
entire web app from being garbage collected when you stop it, because Tomcat's threads will
keep strong reference to web app class loader through these thread locals. 
I will identify shortly these thread locals, and will try to correct them. 
Could anyone tell me how can I reopen this bug? Or do I have to create a new one?


> Using ThreadLocal Call objects in a servlet memory leak both on client and server side
> --------------------------------------------------------------------------------------
>
>          Key: AXIS-935
>          URL: http://issues.apache.org/jira/browse/AXIS-935
>      Project: Axis
>         Type: Bug
>   Components: Basic Architecture
>     Versions: 1.1rc2
>  Environment: Operating System: All
> Platform: All
>     Reporter: Jennifer Jackson

>
> I discovered using Axis in tomcat causes a memory leak.
> It seems using threadlocal in the classes causes a memory leak for each Call 
> that is created.  Threadlocal sticks around until the calling thread dies, and 
> since tomcat keeps threads alive to answer new calls, the threadlocal data 
> never goes away.  The Call object gets stuck in the threadlocal data, which 
> contains the entire soap response and all objects.  This is a BIG memory leak.  
> I initially cleared it by forcing all Call objects to clean their member vars 
> after I was done with a call, then I realized the source was from the thread 
> local class.  Here is some info I found about threadlocal:
> This is stated in the Sun Javadocs for ThreadLocal:
> 	Each thread holds an implicit reference to its copy of a
> 	ThreadLocal as long as the thread is alive and the
> 	ThreadLocal object is accessible; after a thread goes
> 	away, all of its copies of ThreadLocal variables are
> 	subject to garbage collection (unless other references
> 	to these copies exist).
> So, this means that ANY APPLICATION that uses PreparedStatements in a thread
> that 1) either does a lot of PreparedStatements or 2) never dies (i.e., a
> main thread) will ALWAYS eventually have an out of memory error. Simply put,
> this is a MEMORY LEAK. I imagine that the leak is very small, the
> ThreadLocal object only contains one member variable, maybe 64 bytes or less
> (depending on the VM implementation). So, our 60,000 PreparedStatements of 2
> ThreadLocals each times 64 bytes (my wild guess) is 7.5MB.
> Ideas?  I've never used threadlocal myself so this is new to me.

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