example of exception raised in daemon thread

foo2.py

from datetime import datetime
from Queue import Queue
import threading

import time


def worker(q):
    while True:
        item = q.get()
        if isinstance(item, Exception):
            raise item
        print('Working on %s...' % item)
        time.sleep(0.1)
        q.task_done()


def heartbeat():
    the_queue = Queue()
    # create the thread pool
    for n in range(5):
        t = threading.Thread(target=worker, args=(the_queue,))
        t.setDaemon(True)
        t.start()

    while True:
        # mark the start time
        start_time = datetime.utcnow()

        # use Django ORM to get a list of devices
        for device in range(20) + [Exception('Error!')]:
            the_queue.put(device)
        # wait for workers to deal with things
        the_queue.join()
        # mark the end time
        end_time = datetime.utcnow()
        print('finished in %i' % (end_time - start_time).total_seconds())
        time.sleep(0.5)

if __name__ == "__main__":
    heartbeat()