@ptrblck Thank you for your reply. Yes I’m using multiple workers and I set the number of workers to be equal to the number of CPU processors (= 8). And I forgot to mention: training was run on multiple GPUs (4).
It was stuck at the end of training for at least two hours before I shut it down (and this is reproducible, I ran it at least three times). Unfortunately I do not remember what stack trace I got, but I think it was related to dataloaders.
Thanks again!