i am facing exactly this same issue : DataLoader freezes randomly when num_workers > 0 (Multiple threads train models on different GPUs in separate threads) · Issue #15808 · pytorch/pytorch · GitHub 13  in windows 10,
i used, anaconda virtual environment where i have,

python 3.8.5
pytorch 1.7.0
cuda 11.0
cudnn 8004
gpu rtx 3060ti
Is CUDA available: Yes

related post : multiprocessing - PyTorch Dataloader hangs when num_workers > 0 - Stack Overflow 12
and Training freezes when using DataLoader with num_workers > 0 - #5 by mobassir94 10
i got no help for this problem since last 9 days,so re posting about it here!
@ptrblck