[Mongrel] Determining ideal number of Mongrels for an app?

Philip Hallstrom mongrel at philip.pjkh.com
Tue Nov 28 12:03:06 EST 2006


> What's a rule of thumb for guesstimating how many
> Mongrels to use in a cluster for an app? I have an app
> that gets about 5000 unique visitors per day. I
> figured I'd give it plenty of Mongrels -- twenty to be
> specific. After running out of memory and hitting the
> swap periodically, I scaled it back to five and it
> still seems to serve up visitors fine. So, is there
> some super-secret math fomula I can use to determine
> the ideal number of Mongrels I should start in a
> cluster for an app?

http://mongrel.rubyforge.org/docs/how_many_mongrels.html

Just for reference, we get about 500,000 pages a day and run 4 mongrel 
processes... we've got about 20 servers[1], but 4 gives us the best 
performance.

[1] We don't need 20 except for about one month a year when we do about 8 
million pages a day... then they come in handy, but even then they don't 
sweat that much.

-philip


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