def keep_alive(self):
        """Keeps a process alive. If the process terminates, it will restart it
        The terminated processes become zombies. They die when their parent
        terminates
        """
        while True:
            pid = self.execute_in_background()
            p = psutil.Process(pid)
            while p.is_running() and str(p.status) != 'zombie':
                os.system('sleep 5')