parallel_processes.py

#!/usr/bin/env python

from __future__ import print_function
import collections
import subprocess
import time

ProcTuple = collections.namedtuple('ProcTuple', ['process', 'command',
                                                 'start_time'])

commands = [
    ['sleep', '10'],
    ['sleep', '3'],
    ['sleep', '1'],
    ['sleep', '2'],
    ['sleep', '9'],
]
processes = collections.deque()
for command in commands:
    p = subprocess.Popen(command)
    processes.append(ProcTuple(process=p,
                               command=' '.join(command),
                               start_time=time.time()))

while processes:
    pt = processes.popleft()
    if pt.process.poll() is None:
        processes.append(pt)
    else:
        run_time = time.time() - pt.start_time
        print('{} returned with {} in {:.2f} sec.'.format(
            pt.command, pt.process.returncode, run_time))