python - ftplib - download with showing hash mark on screen and be able to interrupt anytime

Question

I want to use ftplib to download a file.

import ftplib

class Ftp:
  def start(self):
    self.ftp = ftplib.FTP('speedtest.tele2.net')
    self.ftp.login()
    with open('1GB.zip', 'wb') as f:
      result = self.ftp.retrbinary('RETR 1GB.zip', f.write)

  def stop(self):
    self.ftp.sock.close()

My first question is, when I call start(), I can see there is a file in File Explorer which its size is keep growing up. However, nothing on the screen. How can I call print('#', end='') while downloading? Like the following pic.

Second. When I call stop(), there is nothing happened because the file size is keep growing up. I've also try self.ftp.abort() but it will hang the whole process. How can I stop the downloading process at any time?

Answer 1

As soon as you call the start method and call retrbinary, the execution thread will get stuck in there until the download completes. You can do nothing during that time.

Check if the FTP library allows to pass a callback function that you can then use to show progress.

The alternative is to use a FTP library that support asyncio which will free the main thread and allow you to display progress or do other things while the file download.

The other solution that is not as clean is to use multiprocessing that will start an entire new Python process to execute your start method. Meanwhile you can use the main process to show progress.