在生成和运行子进程时显示进度 [英] showing progress while spawning and running subprocess

问题描述

我需要在生成和运行子进程时显示一些进度条或其他东西.我怎么能用python做到这一点?

I need to show some progress bar or something while spawning and running subprocess. How can I do that with python?

import subprocess

cmd = ['python','wait.py']
p = subprocess.Popen(cmd, bufsize=1024,stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
p.stdin.close()
outputmessage = p.stdout.read() #This will print the standard output from the spawned process
message = p.stderr.read()

我可以用这段代码生成子进程，但我需要在每一秒过去时打印出一些东西.

I could spawn subprocess with this code, but I need to print out something when each second is passing.

推荐答案

由于子进程调用是阻塞的，所以在等待时打印出来的一种方法是使用多线程.下面是一个使用线程的例子._Timer:

Since the subprocess call is blocking, one way to print something out while waiting would be to use multithreading. Here's an example using threading._Timer:

import threading
import subprocess

class RepeatingTimer(threading._Timer):
    def run(self):
        while True:
            self.finished.wait(self.interval)
            if self.finished.is_set():
                return
            else:
                self.function(*self.args, **self.kwargs)


def status():
    print "I'm alive"
timer = RepeatingTimer(1.0, status)
timer.daemon = True # Allows program to exit if only the thread is alive
timer.start()

proc = subprocess.Popen([ '/bin/sleep', "5" ])
proc.wait()

timer.cancel()

另外，在使用多个管道时调用 stdout.read() 会导致死锁.应改用 subprocess.communicate() 函数.

On an unrelated note, calling stdout.read() while using multiple pipes can lead to deadlock. The subprocess.communicate() function should be used instead.

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