问Python线程-使用有限的线程，遍历n个项目

EN

#!/usr/bin/env 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 ThreadUrl(threading.Thread):
"""Threaded Url Grab"""
def __init__(self, queue):
  threading.Thread.__init__(self)
  self.queue = queue

def run(self):
  while True:
    #grabs host from queue
    host = self.queue.get()

    #grabs urls of hosts and prints first 1024 bytes of page
    url = urllib2.urlopen(host)
    print url.read(1024)

    #signals to queue job is done
    self.queue.task_done()

start = time.time()
def main():

#spawn a pool of threads, and pass them queue instance 
for i in range(5):
  t = ThreadUrl(queue)
  t.setDaemon(True)
  t.start()

#populate queue with data   
  for host in hosts:
    queue.put(host)

#wait on the queue until everything has been processed     
queue.join()

main()
print "Elapsed Time: %s" % (time.time() - start)

if self.queue.task_done():
    return host