Python threading with Exception catching

test_threading.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
from time import sleep
import sys
import threading
import Queue

ERROR_OCCURRED = object()

      
def test_thread():
    q = Queue.Queue(maxsize=3)
    t_get_items = threading.Thread(
        target=get_items,
        args=(q, 2),
    )
    t_get_items.start()
    
    q_result = Queue.Queue(maxsize=3)
    t_read_items = threading.Thread(
        target=read_items,
        args=(q, q_result, 6),
    )
    t_read_items.start()
    
    while True:
        msg = q_result.get()
#        print msg
        if msg is ERROR_OCCURRED:
            print "Got ERROR object"
            raise ValueError('Not 6!')
        if msg is None:
            break
        
    t_get_items.join()
    t_read_items.join()


def get_items(q, division):
    items = range(100)
    items = [item for item in items if item // division]
    for item in items:
        q.put(item)
    q.put(None)
    

def read_items(q, q_result, division):
    while True:
        msg = q.get()
        if msg is None:
            q_result.put(None)
            break
        item = msg
        print item
        try:
            print_item(q_result, item)
        except ValueError:
            q_result.put(ERROR_OCCURRED)
            break


def print_item(q, item):
    if item == 6:
        print "Got 6"
        raise ValueError('Not 6!')
    else:
        q.put(item)


def main():
    count = 0
    while True:
        try:
            some_thread()
        except Exception:
            print ("Error Occurred, try again (%d)" % count)
            count += 1
            sleep(1)


if __name__ == "__main__":
    test_thread()
    print("Finished")

see also multithreading - Catch a thread's exception in the caller thread in Python - Stack Overflow