Do you mean in train.py author is using dataloader for val_loader and train_loader which is like this:
batch_size=args.batch_size, shuffle=False,       num_workers=args.workers, pin_memory=True)
I shall change both val_loader and train_loader like this:
batch_size=args.batch_size, shuffle=False,
num_workers=0, pin_memory=True)
Sorry I am new in deep learning and Pytorch