Python中利用生成器实现的并发编程

#coding=utf-8
import time
import sys
# 生产者
def produce(l):
i=0
while 1:
if i < 5:
l.append(i)
yield i
i=i+1
time.sleep(1)
else:
return
 
# 消费者
def consume(l):
p = produce(l)
while 1:
try:
p.next()
while len(l) > 0:
print l.pop()
except StopIteration:
sys.exit(0)
l = []
consume(l)

import stackless
import urllib2
def output():
while 1:
url=chan.receive()
print url
f=urllib2.urlopen(url)
#print f.read()
print stackless.getcurrent()
 
def input():
f=open('url.txt')
l=f.readlines()
for i in l:
chan.send(i)
chan=stackless.channel()
[stackless.tasklet(output)() for i in xrange(10)]
stackless.tasklet(input)()
stackless.run()