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My setup is django 1.3 and the default mod_wsgi and apache packages for ubuntu 10.04. I tested one view of my app on my development VM (DEBUG and debugging toolbar off):

ab -n 200 -c 5

and got 4 requests per second. This seemed slow so I simplified the queries, used indexes, etc. to the point where debugging toolbar tells me I have 4 queries taking 8ms. Running the same test, I only get 8 requests per second. The CPU seems to be at 100% the whole time. This seems quite slow for what is now a quite simple view, but it is just a low powered VM.

I decided to start up a large ec2 instance (4 cpu) to see what kind of performance I would get on that class of machine and was surprised to only get 13 requests per second. How can I change the configuration of apache/mod_wsgi to get more performance out of this class of machine?

I think I am using worker rather than prefork:

$ /usr/sbin/apache2 -l
Compiled in modules:

My worker configuration is:

<IfModule mpm_worker_module>
    StartServers          2   
    MinSpareThreads      25  
    MaxSpareThreads      75  
    ThreadLimit          64  
    ThreadsPerChild      25  
    MaxClients          150 
    MaxRequestsPerChild   0   

and my WSGI settings look like this:

WSGIScriptAlias / /home/blah/site/proj/
WSGIDaemonProcess blah user=blah group=blah processes=1 threads=10
WSGIProcessGroup blah

Thanks very much for your help!

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I'm not exactly sure how the apache benchmarking tool works, but seeing as it spawns a ton of connections I would assume it uses a fair amount of cpu and is probably what's killing your performance... Try running ab on a different machine. – photoionized Apr 21 '11 at 22:33
you may get more responses from Webmasters – Mike Pennington Apr 22 '11 at 2:10
Thanks @photoionized, I never considered that. I tried it from another instance and got the same results, though. – asciitaxi Apr 22 '11 at 2:24
Wasn't aware of Webmasters, I'll repost over there. Thanks, Mike. – asciitaxi Apr 22 '11 at 2:25

Increase WSGIDaemonProcess procecesses to at least twice the number of cpus and try again

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