Python : how to stop a thread that's waiting for a .recv()

Question

I have this thread running :

def run(self):
    while 1:
        msg = self.connection.recv(1024).decode()

I wish I could end this thread

Answer 1

Two solutions:

1) Don't stop the thread, just allow it to die when the process exits with sys.exit()

2) Start the thread with a "die now" flag. The Event class is specifically designed to signal one thread from another.

The following example starts a thread, which connects to a server. Any data is handled, and if the parent signals the thread to exit, it will. As an additional safety feature we have an alarm signal to kill everything, just it case something gets out of hand.

source

import signal, socket, threading

class MyThread(threading.Thread):
    def __init__(self, conn, event):
        super(MyThread,self).__init__()
        self.conn = conn
        self.event = event

    def handle_data(self):
        "process data if any"
        try:
            data = self.conn.recv(4096)
            if data:
                print 'data:',data,len(data)
        except socket.timeout:
            print '(timeout)'

    def run(self):
        self.conn.settimeout(1.0)
        # exit on signal from caller
        while not self.event.is_set():
            # handle any data; continue loop after 1 second
            self.handle_data()
        print 'got event; returning to caller'


sock = socket.create_connection( ('example.com', 80) )
event = threading.Event()

# connect to server and start connection handler
th = MyThread(conn=sock, event=event)

# watchdog: kill everything in 3 seconds
signal.alarm(3)

# after 2 seconds, tell data thread to exit 
threading.Timer(2.0, event.set).start()

# start data thread and wait for it
th.start()
th.join()

output

(timeout)
(timeout)
got event; returning to caller