Hello everybody!

When I call fork() inside a daemon thread, the main thread in the child process has the "daemon" property set to True. This is very confusing, since the program keeps running while the only thread is a daemon. According to the docs, if all the threads are daemons the program should exit. Here is an example:


import os
import threading


def child():
assert not threading.current_thread().daemon # This shouldn't fail


def parent():
new_pid = os.fork()
if new_pid == 0:
child()
else:
os.waitpid(new_pid, 0)


t = threading.Thread(target=parent)
t.setDaemon(True)
t.start()
t.join()
Is it a bug in the CPython implementation? 
Also let's assume the second example. I have another non-daemon thread in the child process and want to detect this situation. Does anybody know a way to find such fake daemon threads that are really main threads? Best regards, Elizaveta Shashkova.