On 09/11/2014, at 6:24 AM, sags <[email protected]> wrote:
> Hi Graham,
>
> I am been reading your blogs and posts on mod_wsgi configurations. We build
> some programming modules using an open source django based application
> originally developed for MOOCs. We modified the application based on our
> requirements but we didn't change much underlying frame work of that open
> source code.The application is running fine but server some time crashed due
> to out of memory issue. At a time around 30 students use this application in
> a class. We monitored, using free -m command, approximately 30 students when
> using the application at the same time, the memory consumption approximately
> goes down by 200-300 MB. But the problem is once students log out from the
> sessions, the memory doesn't seem to get released. Due to which the memory
> consumption goes on increasing again and again. For the time being we have
> wrote a script to clear the cache if memory goes below 500 MB using echo 1 >
> /proc/ .../drop_caches and it seems to be freeing lot of memory. Is there
> some permanent solution to it. We are using red hat VM server for hosting our
> application. We except more teachers using this application, which means
> traffic is going to be high in future.
>
> FYI: We are using mod_wsgi deamon mode with processes = 2 and Threads = 15
>
>
>
> Is it due to the django or could it be due to OS or httpd configuration
> issues?
>
> I would appreciate your feedback on it.
How are you monitoring memory usage and what processes are specifically taking
up the memory?
I don't understand how:
echo 1 > /proc/sys/vm/drop_caches
as described in:
http://linux-mm.org/Drop_Caches
can affect the run time memory usage of specific Python web application
processes.
BTW, in monitoring memory used by Apache, ensure that if using mod_wsgi daemon
mode that you are using the option:
display-name=%{GROUP}
to the WSGIDaemonProcess directive.
By doing this it will result in the process names as shown by 'ps' and 'htop'
being the name of the mod_wsgi daemon process group name. This way you can
distinguish between normal Apache processes and the mod_wsgi daemon process
groups.
For example, for:
WSGIDaemonProcess mysite display-name=%{GROUP} processes=2 threads=15
You will see in 'ps' out:
httpd (or apache2 on some systems) running as root - Apache parent process
httpd (or apache2 on some systems) running as Apache user - Apache child
worker processes
(wsgi:mysite) - mod_wsgi daemon process group processes
if you are pinning it to an Apache processes, which of these is showing
increase memory usage.
Also, what version of Apache and mod_wsgi are you using?
Graham
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