Update pytorch_data_loader_with_multiple_workers.py

[ankit-amazon]

improved compliant example

[san2488]

I'm not sure this the right fix. I think the issue is that for non-zero num_workers, the dataset should not be stored in a list. So the fix is to not use the list.

Using num_workers as zero is a trivial fix but is likely not what the customer wants.

[linghuiluo]

Good point @san2488 I agree with it. It is a compliant case when num_workers = 0. I'd suggest to instead of using datasets.ImageFolder, using a user-defined class and it should have a field which uses numpy array to store image path like DataIter
in this issue pytorch/pytorch#13246, but self.data = [] should be changed to numpy array. In this case, num_workers can be any number bigger than 0

[linghuiluo]

can that data be more realistic rather than just numbers? e.g. path to image files in a folder.