有没有一种方法可以轮询从subprocess.Popen返回的文件句柄? [英] Is there a way to poll a file handle returned from subprocess.Popen?

问题描述

说我写这个:

from subprocessing import Popen, STDOUT, PIPE
p = Popen(["myproc"], stderr=STDOUT, stdout=PIPE)

现在可以了

line = p.stdout.readline()

我的程序等待，直到子进程输出下一行.

my program waits until the subprocess outputs the next line.

我可以对p.stdout做任何魔术，以便我可以读取输出(如果有的话)，否则可以继续吗?我正在寻找类似Queue.get_nowait()

Is there any magic I can do to p.stdout so that I could read the output if it's there, but just continue otherwise? I'm looking for something like Queue.get_nowait()

我知道我可以创建一个用于读取p.stdout的线程，但是假设我无法创建新线程.

I know I can just create a thread for reading p.stdout, but let's assume I can't create new threads.

推荐答案

使用Python标准库中的select模块，请参见 http://docs.python.org/library/select.html . select.select([p.stdout.fileno()], [], [], 0)立即返回一个元组，该元组的项目为三个列表:如果该文件描述符上有内容要读取，则第一个将为非空.

Use the select module in Python's standard library, see http://docs.python.org/library/select.html . select.select([p.stdout.fileno()], [], [], 0) immediately returns a tuple whose items are three lists: the first one is going to be non-empty if there's something to read on that file descriptor.

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