Using subprocess in Python, to communicate between Parent/Child via STDIN pipe (https://groups.google.com/d/msg/python_inside_maya/waJHs-gsS4c/j0_q39Nj4h0J)

child.py

#!/usr/local/bin python

import time
import subprocess


def main():
    p = subprocess.Popen(["python", "child.py"], bufsize=0, stdin=subprocess.PIPE)
    for i in xrange(10):
        p.stdin.write("Parent command: %d\n" % i)
        time.sleep(1)
    p.terminate()


if __name__ == '__main__':
    main()

parent.py

#!/usr/local/bin python

import os
import sys
import time
import threading

def watch():
    t = threading.Thread(target=_watch)
    t.daemon = True
    t.start()

def _watch():
    print "[STDOUT] Watching for stdin..."
    for line in iter(sys.stdin.readline, None):
        print "[STDIN ]", line.strip()

def main():
    print "[STDOUT] Child pid:", os.getpid()
    watch()
    while True:
        print "[STDOUT] Child sleeping..."
        time.sleep(1)
    print "[STDOUT] Child exiting"


if __name__ == '__main__':
    main()

your file names in the gist are switched around parent.py <--> child.py