Question

Is there a way to have the parent that spawned a new thread catch the spawned threads exception? Below is a real basic example of what I am trying to accomplish. It should stop counting when Exception is raised, but I don’t know how to catch it. Are exceptions thread safe? I would love to be able to use the Subprocess module, but I am stuck using Python 2.3 and am not sure how else to do this. Possibly using the threading module?

import time
import thread

def test(): 
    try:
        test = thread.start_new_thread(watchdog, (5,))
        count(10)
    except:
        print('Stopped Counting')

def count(num):
    for i in range(num):
        print i
        time.sleep(1)

def watchdog(timeout):
    time.sleep(timeout)
    raise Exception('Ran out of time')

if __name__ == '__main__':
    test()

UPDATE

My original code was a little misleading. It am really looking for something more like this:

import time
import thread
import os

def test(): 
    try:
        test = thread.start_new_thread(watchdog, (5,))
        os.system('count_to_10.exe')
    except:
        print('Stopped Counting')

def watchdog(timeout):
    time.sleep(timeout)
    raise Exception('Ran out of time')

if __name__ == '__main__':
    test()

I am trying to create a watchdog to kill the os.system call if the program hangs up for some reason.

Answer 1

Why not something like this

def test(): 
    def exeption_cb():
        os._exit()
    test = thread.start_new_thread(watchdog, (5, exception_cb))
    os.system('count_to_10.exe')
    print('Stopped Counting')

def watchdog(timeout, callback):
    time.sleep(timeout)
    callback()

This will stop the entire process. Another thing you could do is to start os.system in a different thread, then countdown and then kill that thread. Something like this,

def system_call():
    os.system('count_to_10.exe')

system_thread = thread.start_new_thread(system_call)
time.sleep(timeout)
system_thread.kill()