python subprocess pipe 实时输出日志

* test11.py

import time
print "1"
time.sleep(2)
print "1"
time.sleep(2)
print "1"
time.sleep(2)
print "1"

* test.py

import subprocess

p = subprocess.Popen("python test11.py", shell=True, stdout=subprocess.PIPE)

# None表示正在执行中

while p.poll() is None: 
　　out = p.stdout.readline() 
　　if out != "": 
　　　　print out