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From "Geoff Millikan" <>
Subject RE: [users@httpd] Apache 2.2 optimization -> Three tips
Date Mon, 22 Mar 2010 10:08:51 GMT
> if your server averages 300 simulatious connections, you need
> to start with 300 servers, and you never want it to drop
> below that number.

Your experience might show otherwise however based on our experience - if we
averaged 300 new customers/min at once (not 300 requests/sec) a
MinSpareServers of 300 wouldn't be enough.

> Yes, a browser can make multiple connections, but this is 
> typically only two
> parallel pipelines, perhaps even four.  

The "average" browser now makes 6 parallel connections per hostname per:

> But 30 workers are not handling the 30 requests comprising
> one user connecting to your site!!!  You just happened
> to hit a magic correlation in your testing :)

I agree, the way I understand the prefork model to work, the 30 processes
aren't each serving one of the 30+ requests this Customer's browser made (is
keepalive tracked across processes?).  However, the way the testing worked
out for us, it seems that way.  We did a lot of testing to come up with our
numbers and just "ball parking" it, the number of servers seemed to work out
best when matched to the number of requests per page.  

Don't take my word for it, use Firebug and test it - if you're seeing big
"waiting" bar times and you know you have the bandwidth on both ends (ask
you web host how much burst or max bandwidth you get), then up the
MinSpareServers and see what happens (comment out the MaxSpareServers).  For
the record, our site averages ~3 requests per second 24-hours a day and
averages about 35 (ugh, I know) requests per page.  Really should be using
CSS sprites to cut down on the number of requests but instead I'm typing
this and pretending I shouldn't be going to bed.  ;-)


"The nine most terrifying words in the English language are: I'm from the
government and I'm here to help." - Ronald Reagan, August 21, 1986

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