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From Plüm, Rüdiger, VF EITO <ruediger.pl...@vodafone.com>
Subject Re: mod_cache responsibilities vs mod_xxx_cache provider responsibilities
Date Thu, 21 Sep 2006 10:18:48 GMT


> -----Ursprüngliche Nachricht-----
> Von: Niklas Edmundsson 
> Gesendet: Donnerstag, 21. September 2006 11:38
> An: dev@httpd.apache.org
> Betreff: Re: mod_cache responsibilities vs mod_xxx_cache 
> provider responsibilities
> 
> 
> On Thu, 21 Sep 2006, Graham Leggett wrote:
> 
> >
> > This means the backend server will still see a spike of 
> traffic while the
> > object is being cached, but the cache will no try and cache multiple
> > entities until the first one wins, which happens now.
> 
> Our patch solves this by pausing read-threads while the object is 
> being cached until there is a known length of the body, with 
> a timeout 
> to detect if the caching thread has died. Drawback is that 

IMHO this waits for a DoS to happen if the requestor can trick the backend
to get stuck with the request. So one request of this type would be sufficient
to DoS the whole server if the timeout is not very short. BTW: What do you
do once the timeout is reached? Do you start a request to the backend of your
own (so timeout = 0 would be more or less the same as today) or do you sent an
error back to the client?

Regards

Rüdiger


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