Hi, I know you why do not reproduce the error. you can reproduce the error by commenting or deleting the piece of code, then run the left codes.
dataloader = torch.utils.data.DataLoader(
H5Dataset('test.h5'),
batch_size=32,
num_workers=0,
shuffle=True
 )

for i, (data, target) in enumerate(dataloader):
    print(data.shape)
if i > 10:
    break