Add torch.utils.show_pickle for showing pickle contents in saved models (#35168)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35168
Sometimes when a saved model isn't working, it's nice to be able to look
at the contents of the pickle files. Unfortunately, pickletools output
isn't particularly readable, and unpickling is often either not possible
or runs so much post-processing code that it's not possible to tell
exactly what is present in the pickled data.
This script uses a custom Unpickler to unpickle (almost) any data into
stub objects that have no dependency on torch or any other runtime types
and suppress (almost) any postprocessing code.
As a convenience, the wrapper can search through zip files, supporting
command lines like
`python -m torch.utils.show_pickle /path/to/model.pt1@*/data.pkl`
When the module is invoked as main, we also install a hack in pprint to
allow semi-resonable formatting of our stub objects.
Test Plan: Ran it on a data.pkl, constants.pkl, and a debug pkl
Differential Revision: D20842550
Pulled By: dreiss
fbshipit-source-id: ef662d8915fc5795039054d1f8fef2e1c51cf40a
