使用subprocess。避免在子程序大量输出时因buffer size满，导致父进程hang住。

subprocess-bufsize-test.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

import subprocess
from StringIO import StringIO

out = StringIO()

sp = subprocess.Popen(["python", "test_output.py"],
                      stdout=subprocess.PIPE,
                      stderr=subprocess.STDOUT)
while sp.returncode is None:
    data = sp.stdout.read()
    
    
    
    out.write(data)
    sp.poll()

print out.getvalue()


#--------------------------
#!/usr/bin/python
# -*- coding: utf-8 -*-

import subprocess
from StringIO import StringIO
import time
out = StringIO()

# sp = subprocess.Popen(["python", "test_output.py"],
#                       stdout=subprocess.PIPE,
#                       stderr=subprocess.STDOUT)


fab_cmd = ["fab" ,"-f",  "test_output.py", "main"]
# fab -f test_output.py main
p = subprocess.Popen(fab_cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)


begin = time.time()
# p.wait() 826
while True:
    print "start.."
    output = p.stdout.readline()
    print "output:",output
    print "end"
    if output == '' and p.poll() is not None:
        break

print "spnt:",time.time() - begin

test_output.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

import sys

for i in range(1000):
    print "WARNING: hello jaypei from stdout ..."

for i in range(1000):
    print >> sys.stderr, "WARNING: hello jaypei from stderr ..."
    
    
#------------------------
from fabric.api import cd,run,env,hosts, task

env.hosts=['root@182.92.67.22:22']

env.password='xxxxxxx'


def get_disk_usage():
    ret = run("ls /home")
    return ret


def get_date(disk):
    ret = run("ls /")
    return ret

@task
def main():
    for i in range(300):
        disk = get_disk_usage()
        xx = get_date(disk)
        print "out:",disk


# http://stackoverflow.com/questions/8077868/python-subprocess-popen-and-subprocess-call-hang
# http://www.cnblogs.com/icejoywoo/p/3627397.html
# http://www.macaronikazoo.com/?p=607