Re: [cobalt-users] httpd configuration on RaQ/RaQ2/RaQ3

[Duncan Laurie <duncan@xxxxxxxxxx>]

"Drew T. Nichols #333" wrote:
> 
> Question for everyone...
> I've been running Apache for 5 years now but never really "thought" about it
> and performance issues...  A friend of mine was looking at httpd.conf and saw
> the StartServers and Max/Min SpareServers values on the RaQ2 and laughed.
> 
> Seems that Netscape connects to 4 "servers" at one time.  So my friend
> recommends 60 start servers, or 15 simulataneous users.  Any comments on
> this?  The Cobalt out of the box value is 5.
> 
> Regards,
> Drew


The StartServers directive determines only how many server child processes are
started when the web server is initially brought up.  It has no bearing on how
many simultaneous connections can be handled; for that see the MaxClients
directive (default is 150).

If you set the StartServers at 60, and restart your web server you will run out
of memory fast...  on raq2 figure 6MB virtual memory usage (~1MB resident) per
httpd process * 60 is 360MB total usage (or 60MB resident).  Those numbers are
higher for raq3 or any SSL enabled web server, and even higher if you add in
things like mod_php or mod_perl.

The {Min,Max}SpareServers directives define a pool of server child processes to
handle requests.  The desired effect is to reduce the initial cost of creating
child processes when a new connection is established--and hopefully reduce the
startup time for web sites.

This is where you should focus performance tweaking.  You might set
MaxSpareServers higher so that in high-traffic time periods there will be
plenty of extra child processes sitting around (not currently serving any
requests), but they will eventually be killed off by the parent if the traffic
dies down.  Tweaking the MinSpareServers value will define a minimum number of
spare child processes at any one time--apache will never let the number of idle
child processes slip below this value.


-duncan