How to pass and run a callback method in Python

I have a Manager (main thread), that creates other Threads to handle various operations. I would like my Manager to be notified when a Thread it created ends (when run() method execution is finished).

I know I could do it by checking the status of all my threads with the Thread.isActive() method, but polling sucks, so I wanted to have notifications.

I was thinking of giving a callback method to the Threads, and call this function at the end of the run() method:

class Manager():
    ...
    MyThread(self.on_thread_finished).start() # How do I pass the callback

    def on_thread_finished(self, data):
        pass
    ...

class MyThread(Thread):
    ...
    def run(self):
        ....
        self.callback(data) # How do I call the callback?
    ...

Thanks!

Edit Report

1 Answer

If you want the main thread to wait for children threads to finish execution, you are probably better off using some kind of synchronization mechanism. If simply being notified when one or more threads has finished executing, a Condition is enough:

import threading

class MyThread(threading.Thread):
    def __init__(self, condition):
        threading.Thread.__init__(self)
        self.condition = condition

    def run(self):
        print "%s done" % threading.current_thread()
        with self.condition:
            self.condition.notify()


condition = threading.Condition()
condition.acquire()

thread = MyThread(condition)
thread.start()

condition.wait()

However, using a Queue is probably better, as it makes handling multiple worker threads a bit easier.

answered 2011-07-23T17:20:30.473

How to pass and run a callback method in Python

1 Answer

Your Answer