Support debugger

[apoorvkh]

[apoorvkh]

https://github.com/microsoft/debugpy

[apoorvkh]

https://code.visualstudio.com/docs/python/debugging#_remote-script-debugging-with-ssh

Basically the way this would work:

• Selected worker (which the debugger will connect to) will start the debugging server (and wait for the connection), right before executing worker_args.function(). All workers should also set a barrier().

import debugpy

local_ip: str
random_port: int

debugpy.listen((local_ip, random_port))
debugpy.wait_for_client()

• Launcher should start a TCP tunnel (via SSH forwarding) to that port. Launcher should print the local mapped port.
• User can attach Python debugger in vscode to that local port.