Python 3 KeyboardInterrupt Multithreading

Question

I am trying to have a main thread wait for its worker threads to finish using the following code, but when I try to interrupt it with Ctrl+C it doesn't stop

import threading
import sys
exit = threading.Event()

#pass it to the threads

try:
    exit.wait()
    print('Goodbye')
    sys.exit()
except KeyboardInterrupt:
    print('Interrupted')
    sys.exit()

UPDATE Nothing prints. All background threads are daemons.

What platform are you on? On Linux or macOS (unless you're using 3.0-3.1, which are basically broken), I believe all waits on threading objects should be interruptible by signals, and, once it's interrupted, Python will immediately process the SIGINT as a KeyboardInterrupt. But on Windows… I'm not sure how that works, but you may need something more. — abarnert
– abarnert, Commented Jul 24, 2018 at 23:34
Also, I assume the main thread is still blocked on that exit.wait(), and hasn't yet printed Goodbye', right? (Because otherwise, it's already left the try/except block, so obviously the try can't capture the exception.) — abarnert
– abarnert, Commented Jul 24, 2018 at 23:35
I am on Windows. The main thread is still blocked. All my background threads are currently daemons. — Colin Sergi
– Colin Sergi, Commented Jul 25, 2018 at 11:43

Nitikesh Pattanayak · Accepted Answer · 2018-07-25 12:32:07Z

1

import threading
import sys
import time
exit = threading.Event()

#pass it to the threads

try:
    print("hi")
    time.sleep(20)
    print('Goodbye')
    sys.exit()
except KeyboardInterrupt:
    print('Interrupted')
    sys.exit()

Please try the above statement to test your code. i have tested it and its working fine for me.

As you are using exit.wait() without giving any timeouts, its running for infinite seconds. So please put some time as an agument. Follow the below code:

exit = threading.Event()

#pass it to the threads

try:
    print("hi")
    exit.wait(5)
    print('Goodbye')
    sys.exit()
except KeyboardInterrupt:
    print('Interrupted')
    sys.exit()

answered Jul 25, 2018 at 12:32

Nitikesh Pattanayak

8411 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Colin Sergi Over a year ago

I am trying to have the main thread wait indefinitely unless interrupted, ideally without simply have a while loop running checking for a flag.

Colin Sergi Over a year ago

Is that possible??

Nitikesh Pattanayak Over a year ago

Thats possible if you will use Loops for that. But using Wait() its impossible.

Collectives™ on Stack Overflow

Python 3 KeyboardInterrupt Multithreading

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related