multithreading - Python threading module error: 'NoneType' object is not callable -

my screen displays <type 'exceptions.typeerror'>: 'nonetype' object not callable when run code below:

import threading import urllib2 import queue import time  hosts = ["http://baidu.com", "http://yahoo.com"]  queue = queue.queue()  class threadurl(threading.thread):     """ threaded url grab """     def __init__(self, queue):         threading.thread.__init__(self)         self.queue = queue      def run(self):         while true:             #grabs host queue             host = self.queue.get()              #grabs urls of hosts , prints first 1024 byte of page             url = urllib2.urlopen(host)              #signals queue job done             self.queue.task_done()  start = time.time() def main():     in range(2):         t = threadurl(queue)         t.setdaemon(true)         t.start()          host in hosts:             queue.put(host)      queue.join()  main() print "elapsed time: %s" % (time.time() - start) 

this error details:

exception in thread thread-3 (most raised during interpreter shutdown): traceback (most recent call last): file "/usr/local/lib/python2.7/threading.py", line 808, in __bootstrap_inner file "url_thread.py", line 21, in run file "/usr/local/lib/python2.7/queue.py", line 168, in file "/usr/local/lib/python2.7/threading.py", line 332, in wait <type 'exceptions.typeerror'>: 'nonetype' object not callable 

what's wrong code? lot.

it's python 2.7 bug - shutdown exception in daemon thread. make threads non-deamon , pass sentinel through queue signal them exit, join them main thread.

import threading import urllib2 import queue import time  hosts = ["http://baidu.com", "http://yahoo.com"]  queue = queue.queue()  class threadurl(threading.thread):     """ threaded url grab """     def __init__(self, queue):         threading.thread.__init__(self)         self.queue = queue      def run(self):         while true:             #grabs host queue             host = self.queue.get()             if host none:                 self.queue.task_done()                 return              #grabs urls of hosts , prints first 1024 byte of page             url = urllib2.urlopen(host)              #signals queue job done             self.queue.task_done()  start = time.time() def main():     threads = [threadurl(queue) _ in range(2)]     map(lambda t: t.start() threads)     in range(2):         host in hosts:             queue.put(host)     t in threads:         queue.put(none)     queue.join()     map(lambda t: t.join() threads)  main() print "elapsed time: %s" % (time.time() - start)