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From David Smith <d...@cornell.edu>
Subject Re: Simultaneous Requests to servlet
Date Thu, 27 Sep 2007 15:25:23 GMT
Christopher Schultz wrote:

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>David,
>
>David Smith wrote:
>  
>
>>As I understand it one instance of the servlet per webapp is accessed
>>from all threads in a reentrant manner.  This is why you normally can't
>>use any class instance variables in a servlet.
>>    
>>
>
>While this is the most straightforward implementation of a servlet
>container, the servlet specification makes no guarantees whatsoever
>about the lifecycle of a specific servlet. The container is free to
>create a new instance of the servlet to handle every request, or to keep
>a single copy around for the life of the webapp. Or anything in between.
>  
>

Yup.... and all the more reason to store this synchronized data object 
in the servlet context, implementing logic to make it thread-safe.

>The only guarantee made along these lines is for servlets that implement
>SingleThreadModel, which will either require serialized access or
>multiple instances to handle requests. Since this has been deprecated
>but not removed from the spec, I'll bet it will continue to be supported
>  
>
>forever, but it's not a very good idea IMO.
>
>- -chris
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>  
>


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