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From Laurie Harper <>
Subject NullPointer on getParameter
Date Tue, 09 Sep 2003 22:16:58 GMT
Hi, I'm trying to figure out a problem we've encountered since upgrading 
to Tomcat 4.1. I've seen this both on 4.1.24 and 4.1.27. I haven't yet 
reduced it to a specific recipe for reproduction outside the context of 
my application but I do see this quite frequently so I thought I'd see 
if anyone else has come across it...

The problem is that a call to getParameter is getting a 
NullPointerException in the delegation method on CoyoteRequestFacade:

Caused by:
         at org.apache.coyote.tomcat4.CoyoteRequestFacade.
         at javax.servlet.ServletRequestWrapper.

I checked the code and line 178 just a call to the wrapped CoyoteRequest 
object, meaning that reference is null. Now, there's only two ways it 
could be null: a null reference was passed into CoyoteRequestFacade's 
constructor, or CoyoteRequestFacade.clear() was called.

As I understand it, a CoyoteRequestFacade should be associated with a 
request when it starts and not released until the request has completed 
so I'm leaning towards looking at the first possibility. Can anyone give 
me an overview of the 'life cycle' of CoyoteRequestFacade? Where is it 
created, managed, assigned/reclaimed from a particular request, etc?

Better yet, has anyone run into this and found a solution? The nearest 
thing I could find was Bug# 21611 which sounds like the same problem. 
 From the commentary, it doesn't look like there's a known cause yet; 
what would be the best way to track this down (as I say, I can reproduce 
the behaviour easily here)?



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