python os.popen 超时问题

python 版本 2.5.4 (在高版本python中提倡使用 subprocess.Popen 取代 os.popen)

os.popen 会出现过长时间等待导致阻塞问题， 解决方法如下：

def TIMEOUT_COMMAND(command, timeout):
    """call shell-command and either return its output or kill it
    if it doesn't normally exit within timeout seconds and return None"""
    import subprocess, datetime, os, time, signal
    cmd = command.split(" ")
    start = datetime.datetime.now()
    process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    while process.poll() is None:
        time.sleep(0.2)
        now = datetime.datetime.now()
        if (now - start).seconds> timeout:
            os.kill(process.pid, signal.SIGKILL)
            os.waitpid(-1, os.WNOHANG)
            return None
    return process.stdout.readlines()

参考：

http://guozhiwei.iteye.com/blog/973793