Threading / Queue in Python

Question

I intend using threads/queues with python 2.5.2 But it seems that python becomes freezed at the queue.join()-command. The output of the followong code is only: BEFORE

import Queue
import threading

queue = Queue.Queue()

class ThreadUrl(threading.Thread):

    def __init__(self, queue):
        threading.Thread.__init__(self)
        self.queue = queue

    def run(self):
        while True:

            i = self.queue.get()
            print i
            self.queue.task_done()


def main():

    for i in range(5):
        t = ThreadUrl(queue)
        t.setDaemon(True)
        t.start()

    for i in range(5):
        queue.put(i)

    print "BEFORE"
    queue.join()
    print "AFTER"


main()

Has someone an idea about what is going wrong?

queue.put(1) ... not saying this is the solution. But just check the id(queue) is same across all functions ... if not then use global queue in function ... — Ankur Gupta
– Ankur Gupta, Commented Aug 16, 2011 at 7:48
This code looks pretty flawless, and I read this kinda stuff all day :\ — Matt Joiner
– Matt Joiner, Commented Aug 16, 2011 at 7:51
@Eli - I don't think that was a copy-paste error, I think that was his real error. — agf
– agf, Commented Aug 16, 2011 at 7:52

CarenRose · Accepted Answer · 2020-03-19 19:53:58Z

1

I think it is the t.setDaemon(True) part.

So in Python > 2.6, use:

t.setDaemon(True)

And in Python < 2.6, use:

t.daemon = True

edited Mar 19, 2020 at 19:53

CarenRose

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answered Jun 9, 2013 at 15:18

dgg32

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Comments

brandx · Accepted Answer · 2011-08-16 07:55:20Z

0

You run() method on your ThreadUrl class is indented too far. The thread is never started as a result. If you put the indention of the run method at the same indentation level as init() it'll work fine.

answered Aug 16, 2011 at 7:55

brandx

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4 Comments

MultiQueue Over a year ago

Thanks for the hint. But now after calling the queue.put(i)-command the first (or sometimes a second) time python crashes.... !?

brandx Over a year ago

Crashes how? A standard exception or it dies with a signal (SEGV)?

MultiQueue Over a year ago

IDLE freezes and then the window becomes closed by the task manager.

Martin Over a year ago

There might be issues with threading in old versions of IDLE. I think it is resolved in newer versions.

MultiQueue · Accepted Answer · 2011-08-16 13:07:14Z

0

The solution I now found is:

Don't use Python 2.5.2! If one uses Python 2.7.2 instead the code above works very well.

Thank you all!

answered Aug 16, 2011 at 13:07

MultiQueue

1

Comments

Muhammad Suleman · Accepted Answer · 2014-12-01 07:50:36Z

0

Use Daemon=True. That will ensure that your thread exits once the main function is executed.

answered Dec 1, 2014 at 7:50

Muhammad Suleman

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