Re: Preventing an apache mpm prefork from disk trashing

On 05/12/2011 05:45 PM, Emmanuel Kasper wrote:
> Hello
> 
> I have a wordpress blog running with apache in prefork mode ( all debian
> packages ) I have noticed that by traffic peaks ( think reddit ), Apache
> starts to swap heavily becauses it creates too much processes according
> to the RAM of the machine.
> 
> I have been thinking of reducing MaxClients so that MaxClient * ResRAM
> apache process < RAM of the server.
> 
> Is that the correct way to treat this problem ?

Yes, that's the way. And I would also recommend to limit the maximum
number of connection to port 80 with iptables, just in case someone is
flooding. Do a -j DROP, so that clients will retry for a while to
connect in case it goes busy. You can also use bwshare to limit the
number of connections per IP (also a good protection against flooding).

Anyway you do, at some point, you'll have to add more RAM, or do a
cluster with HAproxy, IMHO. RAM is cheap...

Thomas