How do I run some python code in another process?

Question

I want to start, from Python, some other Python code, preferably a function, but in another process.

It is mandatory to run this in another process, because I want to run some concurrency tests, like opening a file that was opened exclusively by the parent process (this has to fail).

Requirements:

• multiplatform: linux, osx, windows
• compatible with Python 2.6-3.x

• AJ.: possible duplicate of What's the best way to duplicate fork() in windows?
• wheaties: @AJ that's about Windows, this is about Python. I don't see how it could possibly be a duplicate.

Answer 1

I would seriously take a look at the documentation for multiprocessing library of Python. From the first sentence of the package's description:

multiprocessing is a package that supports spawning processes using an API similar to the threading module.

It then goes on to say that it side-steps the GIL, which is what it sounds like you're trying to avoid. See their example of a trivial set up:

from multiprocessing import Process
def f(name):
 print 'hello', name
if __name__ == '__main__':
 p = Process(target=f, args=('bob',))
 p.start()
 p.join()

That's a function call being done in another process separate from the process you're inside. Again, all this from the documentation.