On Feb 5, 12:52 pm, John Nagle <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: > > John Nagle wrote: > > >>Graham Dumpleton wrote: > > >>>On Feb 4, 1:05 pm, Paul Rubin <http://[EMAIL PROTECTED]> wrote: > > >>>>"Paul Boddie" <[EMAIL PROTECTED]> writes: > >> Realistically, mod_python is a dead end for large servers, > >>because Python isn't really multi-threaded. The Global Python > >>Lock means that a multi-core CPU won't help performance. > > > The GIL doesn't affect seperate processes, and any large server that > > cares about stability is going to be running a pre-forking MPM no > > matter what language they're supporting. > > Pre-forking doesn't reduce load; it just improves responsiveness. > You still pay for loading all the modules on every request.
No, you don't. Each server is persistent and serves many requests-- it's not at all like CGI, and it reuses the loaded Python image. So if you have, say, an expensive to load Python module, that will only be executed once for each server you start...e.g. if you have Apache configured to accept up to 50 connections, the module will be run at most 50 times; once each of the 50 processes has started up, they stick around until you restart Apache, unless you've configured apache to only serve X requests in one process before restarting it. (The one major feature that mod_python _is_ missing is the ability to do some setup in the Python module prior to forking. That would make restarting Apache somewhat nicer). The major advantage of pre-forking is that you have memory protection between servers, so a bug in one won't take down the whole apache server (just the connection(s) that are affected by that bug). Most shared hosting providers use pre-forking just for these stability reasons. A nice side effect of the memory protection is that you have completely seperate Python interpreters in each process--while each one is reused between connections, they run in independent processes and the GIL doesn't come into play at all. -- http://mail.python.org/mailman/listinfo/python-list
