Is a python script by default daemon?

Question

Not sure whether it's the right way to ask. I will just show you guys some code. Say I write some a simple python script:

#!/usr/bin/python3

import threading
from time import sleep

def echo_num(num):
    sleep(1)
    print('the number is', num)

if __name__ == '__main__':
    threads = []
    for i in range(10):
        t = threading.Thread(target=echo_num, args=(i,), daemon=None)
        threads.append(t)
    for t in threads:
        t.start()

the script exits after all the threads end. After reading the threading-doc I found:

A thread can be flagged as a “daemon thread”. The significance of this flag is that the entire Python program exits when only daemon threads are left. The initial value is inherited from the creating thread.

If the script is daemon(therefore the called threads are also daemon), the called threads should not print anything.

So I assume the python script is by default not daemon?

Attie Attie · Accepted Answer · 2018-06-07T11:33:12

From the documentation you linked, emphasis mine:

daemon A boolean value indicating whether this thread is a daemon thread (True) or not (False). This must be set before start() is called, otherwise RuntimeError is raised. Its initial value is inherited from the creating thread; the main thread is not a daemon thread and therefore all threads created in the main thread default to daemon = False.

Is a python script by default daemon?

1 Answers