python - What does sys.exit really do with multiple threads?

Question

I was really confused by sys.exit() in python. In python documentation, it says "Exit from Python"; does that mean when sys.exit() is called in a python program, the process will exit? If so, the code below shows a different result:

import sys
import time
import threading

def threadrun():
    while(True):
        time.sleep(1)

if __name__=="__main__":
    t=threading.Thread(target=threadrun)
    t.start()
    sys.exit()

Launching this program in linux, result was not the expected one as python documentation says but still run in the system, so what does sys.exit() really do?

Answer 1

As per the documentation sys.exit() raises SystemExit:

Exit the interpreter by raising SystemExit(status).

If SystemExit reaches the default exception handler, it calls handle_system_exit(), which more or less pushes through to Py_Finalize(), which in turn calls wait_for_thread_shutdown() in Python 2, so sys.exit() is the same as the normal falling off the bottom of the main module in waiting for all non-daemon threads to terminate.