Python子进程:知道命令何时完成

Question

我需要一种方法来知道ffmpeg何时完成了它的工作。下面是我的代码:

def on_button_clicked(self, button, progress_bar, filename):
  self.execute(progress_bar, filename)
  progress_bar.set_text('Encoding')
  progress_bar.pulse()
def execute(self, progress_bar, filename):
  cmd = ['ffmpeg', '-y',
         '-i', filename,
         '-r', '30',
         '/tmp/test-encode.mkv']
  process = sp.Popen(cmd, stdin=open(os.devnull))
  progress_bar.set_text('Done')

"完成"永远不会出现。不过，任务已经完成了。我可以在shell窗口中看到ffmpeg已经完成。我怎样才能得到信号?

Answer 1

尝试强制GTK处理set_text:

之后的挂起事件

##  force the refresh of the screen
        while gtk.events_pending():
            gtk.main_iteration()

Answer 2

我是这样做的:

    p = sp.Popen(command, stdin=sp.PIPE, stdout=sp.PIPE, stderr=sp.PIPE)
    def mycallback(p):
        p.poll()
        if p.returncode is None:
            # Waiting for Godot
            return True
        else:
            # Yay, wait is over!
            return False
    GObject.timeout_add(1000, mycallback, p)