Re: [Modeling-users] Database Connections

[Duncan M. <py...@ad...>]

On Aug 4, 2004, at 3:46 PM, Sebastien Bigaret wrote:

>
>         Hi Duncan,
>
>   Before answering and since I've never used the mod_python and any of
> its session management tools, could you please tell:
>
> - which session management module you intend to use?
>   (http://www.modpython.org/FAQ/faqw.py?req=all#3.8)

You bet, and sorry about leaving out that detail. We are using 
mod_python 3.1, and using the built-in session management. Here are the 
links:
http://www.modpython.org/live/current/doc-html/pyapi-sess.html
http://www.modpython.org/live/current/doc-html/pyapi-sess-classes.html

> - how does it work? I mean, from a process or thread perspective, can
>   you be more explicit?

Sure; here's a description of how the python interpreter and something 
called "subinterpreters" work in mod_python:
http://www.modpython.org/live/current/doc-html/pyapi-interps.html

I'm no expert on the internals of mod_python, but here's a quick 
run-down of a typical series of steps apache + a simple mod_python 
setup go through during the lifetime of a request:
http://www.modpython.org/live/current/doc-html/tut-what-it-do.html

We've been running a default mod_python apache configuration: 1 main 
process, and multiple child processes are spawned as needed. I don't 
and have never programmed in threads and don't really understand it, so 
you'll have to forgive my terminology, if incorrect...

I guess we could setup mod_python to run a single interpreter 
(http://www.modpython.org/live/current/doc-html/dir-other-pi.html), I 
would want to do that only if we had to though... I think we would 
loose many of the performance gains our client sought by going with 
mod_python in the first place...


> In short, the answer depends on the answer of those questions; the
> EditorContextSessioning component only provides an easy way to register
> and retrieve the EC based on a session id.

Ah... this is good information.

> The number of connection to
> the database is independent to this component, and is usually 1 (one)
> per process (I really mean process here, not threads, a DB connection 
> is
> shared by threads within a single process). That's why I asked about 
> the
> way mod_python + the session management module you'll use handle
> sessions wrt processes.

You're out of my depth here, but I can dig some more if the above info 
doesn't answer these questions...

Thanks!

Duncan