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From Christian Gottschalch <>
Subject Re: [users@httpd] mod_proxy maximum connections to a backend
Date Wed, 10 Jan 2007 10:23:30 GMT

i think it ist per process, so if you have 100 processes with max value 
200 your Hard Maximum will be 20000 connections, but im not shure.

Documentation says 
The default for a Hard Maximum for the number of connections is the 
number of threads per process in the active MPM.

which makes sense, because every thread can handle one request, to 
handle the request a minimum of one connection to the proxyed server is 
needed, therefore i think it must be a per process setting. In prefork 
mode it is set to 1, because  if you use prefork only one request can be 
handled per process.


George Barnett schrieb:
> Hi All,
> I've asked this on irc and it was suggested that I try asking the dev
> because the docs aren't clear, but I'll ask here aswell.
> I'm using apache httpd 2.2.3 with the event MPM to do some traffic
> throttling to a backend.  What I have is this:
> First, traffic hit a default vhost with lots of rewrite rules such as 
> this:
> RewriteCond %{REQUEST_URI}    ^/page.*$ [NC]
> RewriteCond %{QUERY_STRING}   ^.*pattern.*$ [NC]
> RewriteRule ^(.*)$ http://trafficclass.localhost/$1 [P,L]
> In the hosts file, trafficclass.localhost is, so from there, 
> the
> traffic heads back into a vhost.
> Then I have a vhost with the following in it:
> <VirtualHost>
>  DocumentRoot /opt/apache/htdocs
>  ServerName trafficclass.localhost
>  ProxyRequests off
>  ProxyBadHeader Ignore
>  CustomLog /var/log/apache2/gold-access.log combined
>  Errorlog /var/log/apache2/gold-error.log
>  <Location />
>   ProxyPass max=200 acquire=500
>   # IIS Sucks
>   SetEnv force-proxy-request-1.0 1
>   SetEnv proxy-nokeepalive 1
>  </Location>
> </Virtualhost>
> In my setup I have 100 processes with 64 threads per process.
> Last night during exceptional load, I saw over 3200 connections to the
> backend.  My question - is it possible that max=200 is a per process and
> not server wide limit?
> If so, there's a way to set a server wide limit to the backend?
> Cheers,
> George

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