Re: mod_proxy performance with apache 2.2

Skye Poier Nott <skye@xxxxx> · Thu, 20 Mar 2008 11:13:31 -0700

I originally discovered the problem because the initial "fill" of  

mod_disk_cache from the origin server was taking forever.  The stats I  

list below are with mod_proxy only (mod_cache is loaded, but not  

enabled for any host)

Skye

On 19-Mar-08, at 3:07 PM, Robert Anderson wrote:

I had a similar issue that was caused by caching. Do you have  

mod_cache or mod_disk_cache active? are they clearing properly?

Skye Poier Nott wrote:

Hi Joshua,

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.

Just can't seem to get more than about 4 Mbit/sec out of the  

origin.  I'll give dev@ a ping.

Thanks,
Skye

On 19-Mar-08, at 12:28 PM, Joshua Slive wrote:

On Tue, Mar 18, 2008 at 8:51 PM, Skye Poier Nott <skye@xxxxx> wrote:

Hi,

I am doing some load testing on a reverse proxy with apache 2.2 +
mod_proxy and I'm getting terrible throughput, I was wondering if
anyone had a suggestion.

I have the following config, all on gigabit ethernet:

1 origin server -> 2 mod_proxy servers -> 4 client simulators  

(flood)

The origin and proxy servers are configured with 100 name-based
virtual hosts, the proxy servers with config like this:

<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 on the proxy servers, I fully saturate the  

gigE

on the origin server (~500 Mbit/sec)

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?

I'm not a mod_proxy performance expert (and you might need to ask on

the dev@httpd list to find one), but you should start with the  

basics:

have you looked at the mod_status server-status output? Are you

exceeding MaxClients? Is there anything interesting in the error  

log?

Joshua.

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