I am testing Python threading with the following script:
import threading
class FirstThread (threading.Thread):
def run (self):
while True:
print 'first'
class SecondThread (threading.Thread):
def run (self):
while True:
print 'second'
FirstThread().start()
SecondThread().start()
This is running in Python 2.7 on Kubuntu 11.10. Ctrl+C will not kill it. I also tried adding a handler for system signals, but that did not help:
import signal
import sys
def signal_handler(signal, frame):
sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
To kill the process I am killing it by PID after sending the program to the background with Ctrl+Z, which isn't being ignored. Why is Ctrl+C being ignored so persistently? How can I resolve this?
I think it's best to call join() on your threads when you expect them to die. I've taken some liberty with your code to make the loops end (you can add whatever cleanup needs are required to there as well). The variable die is checked for truth on each pass and when it's True then the program exits.
import threading
import time
class MyThread (threading.Thread):
die = False
def __init__(self, name):
threading.Thread.__init__(self)
self.name = name
def run (self):
while not self.die:
time.sleep(1)
print (self.name)
def join(self):
self.die = True
super().join()
if __name__ == '__main__':
f = MyThread('first')
f.start()
s = MyThread('second')
s.start()
try:
while True:
time.sleep(2)
except KeyboardInterrupt:
f.join()
s.join()
An improved version of @Thomas K's answer:
is_any_thread_alive()
according to this gist, which can terminates the main()
automatically.Example codes:
import threading
def job1():
...
def job2():
...
def is_any_thread_alive(threads):
return True in [t.is_alive() for t in threads]
if __name__ == "__main__":
...
t1 = threading.Thread(target=job1,daemon=True)
t2 = threading.Thread(target=job2,daemon=True)
t1.start()
t2.start()
while is_any_thread_alive([t1,t2]):
time.sleep(0)
KeyboardInterrupt and signals are only seen by the process (ie the main thread)... Have a look at Ctrl-c i.e. KeyboardInterrupt to kill threads in python
Source: Stackoverflow.com