[BUG] - torchvision_tutorial.py fails with a RuntimeError

[svekars]

Add Link

https://pytorch.org/tutorials/intermediate/torchvision_tutorial.html

Describe the bug

Fails in CI and locally on MacOS with:

disable due to RuntimeError: DataLoader worker (pid(s) 20092) exited unexpectedly

The tutorial was disabled in: #2842 - can be enabled after the issue is resolved.

Describe your environment

• macOS and CI
• Pytorch 2.3

cc @datumbox @nairbv @fmassa @NicolasHug @YosuaMichael @sekyondaMeta @kit1980

[alperenunlu]

/assigntome

[alperenunlu]

@svekars Should I just describe the bug or also solve it.

[svekars]

@alperenunlu the task here is to solve the issue and enable the tutorial.

[alperenunlu]

So the main problem is torch.utils.data uses different behavior on different platforms

In MacOS and Windows it uses spawn() on Unix it uses fork() for multiprocessing.

So if we were running a script we should wrap our main script in a if __name__ == "__main__": that will solve the problem but in Jupyter notebooks this also doesn't work so if we want to create a solution for both notebooks and script the best thing come to my mind is checking the platform and setting the num_workers according to that.

@NicolasHug