Development for dual core machine

Paul Rubin http
Sun Aug 19 19:25:24 CEST 2007


Andy <fukazawa at gmail.com> writes:
> >From what I read, I think that simply by making the package run in
> several separate processes (web server, database server, Python
> interpreter, etc.), and/or using multiple threads (which I will
> anyway) the package should be able to use multiple CPUs.

Python threading doesn't support multiple CPU's because of the GIL.

One approach to using your multiple cores is to embed a Python
interpreter into a web server that runs in multiple processes,
e.g. mod_python under Apache.

Another is write your application as a separate process (e.g.  as an
FastCGI), then run multiple instances of it, connected to a concurrent
web server.  For what I'm currently doing, we're using lighthttpd as
the http server and flup to connect to a set of Python FCGI's.

For that matter, if your machine is just dual core, maybe it's ok to
just run a single Python process, figuring that will run on one core
and your database/httpd will run on the other one.  However, you
should figure the dual core situation won't last.  Dual socket
motherboards are fairly cheap these days, so we have a number of
4-core machines (two AMD dual core cpu's); Intel is already shipping
quad core cpu's, so that puts 8 cores in a dual socket board (you can
already buy Macintoshes configured that way).  Higher end server
motherboards have 4 sockets, so you have to expect that 16-core
servers will be common pretty soon.

So if you're working on a cpu-intensive application it's worth your
while figuring out how to parallelize it.

Note that the most careful concurrency stuff probably is in the
database.  Serious ones already know how to use multiple CPU's.



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