programmatically executing and terminating a long-running batch process in python

Question

I have been searching for a way to start and terminate a long-running "batch jobs" in python. Right now I'm using "os.system()" to launch a long-running batch job inside each child process. As you might have guessed, "os.system()" spawns a new process inside that child process (grandchild process?), so I cannot kill the batch job from the grand-parent process. To provide some visualization of what I have just described:

Main (grandparent) process, with PID = AAAA
          |
          |------> child process with PID = BBBB
                         |
                         |------> os.system("some long-running batch file)
                                  [grandchild process, with PID = CCCC]

So, my problem is I cannot kill the grandchild process from the grandparent...

My question is, is there a way to start a long-running batch job inside a child process, and being able to kill that batch job by just terminating the child process? What are the alternatives to os.system() that I can use so that I can kill the batch-job from the main process ?

Thanks !!

Answer 1

subprocess module is the proper way to spawn and control processes in Python.

from the docs:

The subprocess module allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. This module intends to replace several other, older modules and functions, such as:

os.system
os.spawn
os.popen
popen2
commands

so... if you are on Python 2.4+, subprocess is the replacement for os.system

for stopping processes, check out the terminate() and communicate() methods of Popen objects.