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From Christopher Schultz <ch...@christopherschultz.net>
Subject Re: Tomcat 7 - No modifications are allowed to a locked ParameterMap
Date Thu, 03 May 2012 01:07:42 GMT
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David,

On 5/2/12 8:01 PM, David Wall wrote:
> 
> 
> On 5/2/2012 2:17 PM, Caldarale, Charles R wrote:
>> Both this symptom and your earlier one about creating a session
>> after a response has been committed are representative of the
>> kinds of errors seen when a webapp stores references in an
>> inappropriate scope.  For example, keeping a reference to a
>> request or response object in a static field, a session, or a
>> thread-local, will often result in the wrong object being used
>> later on.  This is especially evident under high-load
>> situations...
>> 
>> - Chuck
> 
> Okay, it looks like you put me on the right track. Just discovered
> that one of the servlets uses an instance variable to hold the 
> request/response/session objects. Oy, and it was like that since
> 2008! Not positive this will resolve all the issues, but it's a
> clear bug. Thanks for your tip.

Here's another tip: run "findbugs" against your code. It will complain
about "class members in a Servlet" along with a zillion other things
that you might find will improve your code significantly.

- -chris
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