Thread locking question.

[grocery_stocker]

The following code gets data from 5 different websites at the "same
time".

#!/usr/bin/python

import Queue
import threading
import urllib2
import time

hosts = ["http://yahoo.com", "http://google.com", "http://amazon.com",
         "http://ibm.com", "http://apple.com"]

queue = Queue.Queue()

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

    def run(self):
        while True:
            host = self.queue.get()
            if host is None:
                break
            url = urllib2.urlopen(host)
            print url.read(1024)
            #self.queue.task_done()

start = time.time()

def main():
    for i in range(5):
        t = MyUrl(queue)
        t.setDaemon(True)
        t.start()

    for host in hosts:
        print "pushing", host
        queue.put(host)

    for i in range(5):
        queue.put(None)

    t.join()

if __name__ == "__main__":
    main()
    print "Elapsed Time: %s" % (time.time() - start)


How does the parallel download work if each thread has a lock? When
the program opens www.yahoo.com, it places a lock on the thread,
right? If so, then doesn't that mean the other 4 sites have to wait
for the thread to release the lock?