Re: [modwsgi] daemon mode question

[Graham Dumpleton]

Sounds like it is more of a specific issue with that database which
you would want to ask the developers/community of that database. That
is, how to use from multiple processes at the same time.

I can only offer up general advice at end of:

http://code.google.com/p/modwsgi/wiki/ProcessesAndThreading

Is there any specific reason you can't use a single multithreaded
daemon process? Does the traffic volume warrant multiple processes? Is
your code thread safe?

Graham

On 7 November 2012 01:26, Ferencik Ioan <ferenc...@gmail.com> wrote:
> Hello folks,
>
> I am facing following issue and was wondering whether anybody could have a
> suggestion.
> I am running mod_wsgi /python 2.7.3 on a ubuntu 12.04 box.
>
> My web application is django based but is is using just one view.
> The issue i have is following.
>
> I have a class A. This class uses a metaclass that inserts the instance in a
> object oriented database (dybase).
> The database file is opened by the metaclass and closed when the interpreter
> exits (when i close bpython) using atexit hook.
> The issue is that apache runs this view from multiple processes. SO if i
> query the index for the nr of object each process reports a different
> number.
> The database has exclusive locks but i did not manage to use them correctly.
>
> My point is i do not know exactly what is the best way to:
>
> open/close the database
>
> when to lock the index
>
> so i get correct results.
> FYI if i use the daemon with 1 process everything works fine.
> I hope i wasn't very cryptic.
>
> Regards
>
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[Ferencik Ioan]

Hello Graham,

thanks for the timely reply.

The issue was indeed database specific, I contacted the developers and found that my DB does not support multiple processes.

I have low traffic so I disabled the processes. I could also use only one.

Everything works fine.

I can also say if anyone is interested i open the connection on per interpreter basis

and close it when the mod_wsgi exist (server is restarted/stopped)

Thanks again.

[Graham Dumpleton]

If one database connection per interpreter (process), for a
multithread application there could be an issue if the multiple
threads are trying to use the one database connection. How are you
protecting against that?

Graham

> https://groups.google.com/d/msg/modwsgi/-/pEBHa90BC_0J.