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From Guy Ferraiolo <g...@cnet.com>
Subject Re: mod_proxy performance with apache 2.2
Date Thu, 20 Mar 2008 21:13:01 GMT
Definitely check the service time of the requests.  If your server isn't
closing the connection, flood won't either.  This is the correct
behavior but it's non-intuitive.  If all your times are equal to the
timeout, this could be the problem.  As for why httpd might not be
closing the connection, that can be tricky and also compliant.

Guy

On Thu, 2008-03-20 at 12:56 -0700, Skye Poier Nott wrote:
> (Moved from users@ list as recommended)
> 
> Hi,
> 
> I am doing some load testing on a reverse proxy with apache 2.2 +  
> mod_proxy (no caching) and I'm getting terrible throughput, I was  
> wondering if anyone had a suggestion.
> 
> I have the following test network, all on gigabit ethernet:
> 
> 1 origin server -> 2 mod_proxy servers -> 4 client simulators (flood)  
> doing round-robin on the proxies
> 
> The origin and proxy servers are configured with name-based virtual  
> hosts, the proxy servers with config containing 100 of these:
> 
> <VirtualHost *:80>
>         ServerName w0099.example.com
>         ProxyPass / http://10.100.10.XX:80/w0099/
>         ProxyPassReverse / http://10.100.10.XX:80/w0099/
> </VirtualHost>
> 
> When I start up flood on the client simulators (250 clients each), I  
> only get about 4 Mbit/sec out of the origin server!  I've tried  
> twiddling all the settings in mod_proxy to no avail (like smax=64  
> max=512 ttl=120 min=8 acquire=1)
> 
> If I set up lighttpd+proxy on the proxy servers instead of apache, I  
> fully saturate the gigE on the origin server (~500 Mbit/sec) as  
> expected.
> 
> I've tried changing MaxClients from 256 to 512 to 1024, no effect.
> I've tried changing from MPM prefork to worker, and twiddled threads  
> per child, no effect.
> 
> What could explain this 125x difference in performance?  Is there some  
> sort of resource or lock or something contention in mod_proxy that I  
> should know about?
> 
> Are the virtual host lookups taking too long?  Eventually I'd like to  
> support up to 10,000 virtual hosts through this proxy.  Is there  
> something like mod_vhost_alias for proxy for large configurations?
> 
> Is using subdirectories in ProxyPass slowing things down?  Really, I'd  
> just like to forward all requests for anything to the origin server IP  
> and let the origin worry about serving the right vhost's files.
> 
> Thanks,
> Skye
> 
-- 
Guy Ferraiolo                                   mailto:guyf@CNET.com
Performance Measurement & Analysis              http://CNET.com
CNET                                            tel: 1.908.541.3739
1200 Route 22 East                              fax: 1.908.575.7474
Bridgewater, NJ 08807                           cel: 1.732.618.0250

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