python call external program non-blocking way

Question

is there a way to call an external program inside python and don't wait for its execution to finish?

I tried this, but no luck:

os.system("external_program &")

Normally, if I call external_program & inside a bash shell it executes as a background process. How can I do it inside python? For, my special case, creating another thread does not work. After main python scrip is done, the external program should continue its execution.

Answer 1

Yes, use the subprocess module. For example:

p = subprocess.Popen(['external_program', 'arg1', 'arg2'])
# Process is now running in the background, do other stuff...
...
# Check if process has completed
if p.poll() is not None:
    ...
...
# Wait for process to complete
p.wait()