gmemon gmemon - 5 months ago 29
Python Question

thread.start_new_thread vs threading.Thread.start

What is the difference between

thread.start_new_thread
and
threading.Thread.start
in python?

I have noticed that when
start_new_thread
is called, the new thread terminates as soon as the calling thread terminates.
threading.Thread.start
is the opposite: the calling thread waits for other threads to terminate.

Answer

The thread module is the low-level threading API of Python. Its direct usage isn't recommended, unless you really need to. The threading module is a high-level API, built on top of thread. The Thread.start method is actually implemented using thread.start_new_thread.

The daemon attribute of Thread must be set before calling start, specifying whether the thread should be a daemon. The entire Python program exits when no alive non-daemon threads are left. By default, daemon is False, so the thread is not a daemon, and hence the process will wait for all its non-daemon thread to exit, which is the behavior you're observing.


P.S. start_new_thread really is very low-level. It's just a thin wrapper around the Python core thread launcher, which itself calls the OS thread spawning function.