Will this active wait affect the process duration greatly? If so what can I replace it with?

Question

In the video diet program there is an active wait using a while loop. I want to know if this will affect the process execution time greatly and if so what can I replace it with.

main.py

def update_progress_bar(proc, manager, path: str) -> None:
    pbar = None
    try:
        total = get_total_frames(proc)
        cont = 0
        pbar = initialize_progress_bar(manager, path)
        while True:
            progress = get_current_frame(proc)
            percent = progress / total * 100
            pbar.update(percent - cont)
            cont = percent
    except expect.EOF:
        pass
    finally:
        if pbar is not None:
            pbar.close()

Comments

When is the loop supposed to end? Do one of get_current_frame or pbar.update raise a EOF exception?

---

You can time it and measure the difference. Do it once with ffmpeg (without your program), then redo with your program.

$ time ffmpeg ...
$ time ./program.py ...

Answer 1

For context, I'm assuming this question is related to your other question Show progress bar of a ffmpeg video convertion.
You have spawn a separate process for ffmpeg, so this loop will not affect ffmpeg if this is your question. Your program and ffmpeg are two separate processes and if you have a multi core CPU they will execute in parallel. Nevertheless your program is busy in the loop and this does affect your process, if this is the question. If you don't want your process to be stuck reading the ffmpeg output you have to spawn a new thread.