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From Colm MacCarthaigh <c...@stdlib.net>
Subject Re: [PATCH] mod_disk_cache deterministic tempfiles
Date Thu, 18 Aug 2005 18:09:47 GMT
On Thu, Aug 18, 2005 at 02:00:52PM -0400, Brian Akins wrote:
> Colm MacCarthaigh wrote:
> 
> >So mtime not being recent is no-indication of death, it could easily be
> >a trickling download.
> 
> True. But, if the files mtime has not changed in 120 seconds (for 
> example) the download is probably hung?

120 second stalls arn't uncommon, and there are plenty of overloaded
servers and terrible CGI's that have those kind of response times. A
major use of mod_cache to solve just that problem, but any approach
- no matter what number of seconds you pick - will always introduce
inefficiency.

If you pick a value that is too low, you'll never cache slow-to-serve
content. If you pick a value that is too high, you'll end up sending a
lot of requests to the (already slow) backend.

There might be a solution in using the scoreboard.

-- 
Colm MacCárthaigh                        Public Key: colm+pgp@stdlib.net

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