def down(url,n):
print 'item '+str(n)+' start '
filename=urllib2.unquote(url).decode('utf8').split('/')[-1]
urllib.urlretrieve(url, filename)
print 'item '+str(n)+' finish '

def worker():
while True:
i = q.get()
url=i[0]
n=i[1]
down(url,n)
q.task_done()

if __name__=="__main__":

num_worker_threads=100

f=open('url.txt')
l=f.readlines()
q = Queue.Queue()
for i in range(num_worker_threads):
t = threading.Thread(target=worker)
t.daemon = True
t.start()

for i in range(0,len(l)):
q.put((l[i],i))

q.join()