Run a process and kill it if it doesn't end within one hour

The subprocess module will be your friend. Start the process to get a Popen object, then pass it to a function like this. Note that this only raises exception on timeout. If desired you can catch the exception and call the kill() method on the Popen process. (kill is new in Python 2.6, btw)

import time

def wait_timeout(proc, seconds):
    """Wait for a process to finish, or raise exception after timeout"""
    start = time.time()
    end = start + seconds
    interval = min(seconds / 1000.0, .25)

    while True:
        result = proc.poll()
        if result is not None:
            return result
        if time.time() >= end:
            raise RuntimeError("Process timed out")
        time.sleep(interval)

There are at least 2 ways to do this by using psutil as long as you know the process PID. Assuming the process is created as such:

import subprocess
subp = subprocess.Popen(['progname'])

...you can get its creation time in a busy loop like this:

import psutil, time

TIMEOUT = 60 * 60  # 1 hour

p = psutil.Process(subp.pid)
while 1:
    if (time.time() - p.create_time()) > TIMEOUT:
        p.kill()
        raise RuntimeError('timeout')
    time.sleep(5)

...or simply, you can do this:

import psutil

p = psutil.Process(subp.pid)
try:
    p.wait(timeout=60*60)
except psutil.TimeoutExpired:
    p.kill()
    raise

Also, while you're at it, you might be interested in the following extra APIs:

>>> p.status()
'running'
>>> p.is_running()
True
>>>

I had a similar question and found this answer. Just for completeness, I want to add one more way how to terminate a hanging process after a given amount of time: The python signal library https://docs.python.org/2/library/signal.html

From the documentation:

import signal, os

def handler(signum, frame):
    print 'Signal handler called with signal', signum
    raise IOError("Couldn't open device!")

# Set the signal handler and a 5-second alarm
signal.signal(signal.SIGALRM, handler)
signal.alarm(5)

# This open() may hang indefinitely
fd = os.open('/dev/ttyS0', os.O_RDWR)

signal.alarm(0)          # Disable the alarm

Since you wanted to spawn a new process anyways, this might not be the best soloution for your problem, though.