Add exception classification to torch.multiprocessing.spawn (#45174)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45174
Introduce different types of exceptions that map to different failures
of torch.multiprocessing.spawn. The change introduces three different exception types:
ProcessRaisedException - occurs when the process initiated by spawn raises an exception
ProcessExitedException - occurs when the process initiated by spawn exits
The following logic will allow frameworks that use mp.spawn to categorize failures.
This can be helpful for tracking metrics and enhancing logs.
Test Plan: Imported from OSS
Reviewed By: taohe
Differential Revision: D23889400
Pulled By: tierex
fbshipit-source-id: 8849624c616230a6a81158c52ce0c18beb437330
