Maybe try stackoverflow, since this isn't really a numpy question.
To run a command like "python myscript.py arg1 arg2" in a separate process, you can do:
    p = subprocess.Popen("python myscript.py arg1 arg2".split())
You can launch many of these, and if you want to know if a process p is over, you can call p.poll().
I'm sure there are other (and better) options though.

-=- Olivier