Exit from imported script in python

abc.py:

import xyz
#also import other required modules
#other required code
xyz.func()
#other required code

xyz.py:

import threading
import sys
#few threads
def func():

    #start all threads
    threads.start()
    threads.join(timeout)
    #if not joined within given time, terminate all threads and exit from xyz.py
    if (threads.isAlive()):
        sys.exit()
#I used sys.exit() but it is not working for me.What else can I do here? `

I have a python script abc.py that imports another python script xyz.py. I am using sys.exit() function in xyz.py. Problem I am facing here is when sys.exit() function is executed in xyz.py file, my main file i.e. abc.py also gets terminated. I don't want this to happen. My file abc.py should remain ON even though xyz.py file terminates. Is there any way to achieve this? I will be grateful to receive any help/guidance.I am using python 2.6.6 on centos 6.5.