How To Backport Multiprocessing to 2.4 and 2.5

Just let these guys do it for you.

My hats off to them for this contribution to the community. It is much appreciated and will find use quickly, I'm sure. I know I have some room for it in my toolbox. Hopefully, the changes will be taken back to the 2.6 line so that any bugfixes that come will help stock Python and the backport.

So, if you don't follow 2.6/3.0 development you might not be aware of multiprocessing, the evolution of integrating the pyprocessing module into the standard library. It was cleaned up and improved as part of its inclusion, so its really nice to have the result available to the larger Python user base that is still on 2.5 and 2.4. Although some edge cases might still need to be covered, the work is stable quickly.

Here's an overview incase you don't know, so hopefully you can see if it would be useful for any of your own purposes. I think, starting out, there is more potential for this backport than the original multiprocessing module. Thus, I hope this introduction is found useful by a few people.

>>> from multiprocessing import Process, Pipe

>>>

>>> def f(conn):

...     conn.send([42, None, 'hello'])

...     conn.close()

...

>>> parent_conn, child_conn = Pipe()

>>> p = Process(target=f, args=(child_conn,))

>>> p.start()

>>> print parent_conn.recv()   # prints "[42, None, 'hello']"

[42, None, 'hello']

>>> p.join()

This is an example from the multiprocessing docs, utilizing its Pipe abstraction. The original idea was emulating the threading model. The provisions are basic, but give you what you need to coordinate other Python interpreters. Aside from pipes, there are also queues, locks, and worker pools provided. If you're working on a multicore system with a problem that can be broken up for multiple workers, you can stop complaining about the GIL and dispatch your work out to child processes. Its a great solution and this makes it a lot easier, giving the anti-thread crowd a nice boost in validation and ease-of-convincing. That's a good thing for all of us, because it means software that takes advantage of our new machines and more people who can write that software without the problems threading always gave us. Of course, some problems, like locks, can be problematic in the wrong situation, so don't think I'm calling anything a silver bullet. The point is, it improves. Nothing perfects, and I know that.