Python3.9 dataloader and torch.nn.DataParallel errors

hi, when I use python3.9 torch.nn.parallel, I got the following errors:
Traceback (most recent call last):
File “/home/modelrep/manshan/python_examples/DataLoader/other_seeds/test_robustness.py”, line 319, in
rob_acc_multi_real = run_attack(TestdataLoader,fmodel_multi_real,epsilons,device).numpy()
File “/home/modelrep/manshan/python_examples/DataLoader/other_seeds/test_robustness.py”, line 169, in run_attack
for i_batch, sample_batched in enumerate(TestdataLoader):
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/site-packages/torch/utils/data/dataloader.py”, line 631, in next
data = self._next_data()
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/site-packages/torch/utils/data/dataloader.py”, line 1329, in _next_data
idx, data = self._get_data()
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/site-packages/torch/utils/data/dataloader.py”, line 1295, in _get_data
success, data = self._try_get_data()
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/site-packages/torch/utils/data/dataloader.py”, line 1133, in _try_get_data
data = self._data_queue.get(timeout=timeout)
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/multiprocessing/queues.py”, line 122, in get
return _ForkingPickler.loads(res)
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/site-packages/torch/multiprocessing/reductions.py”, line 495, in rebuild_storage_fd
fd = df.detach()
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/multiprocessing/resource_sharer.py”, line 57, in detach
with _resource_sharer.get_connection(self._id) as conn:
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/multiprocessing/resource_sharer.py”, line 86, in get_connection
c = Client(address, authkey=process.current_process().authkey)
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/multiprocessing/connection.py”, line 502, in Client
c = SocketClient(address)
File “/scratch/modelrep/manshan/anaconda/envs/branch-env/lib/python3.9/multiprocessing/connection.py”, line 630, in SocketClient
s.connect(address)
FileNotFoundError: [Errno 2] No such file or directory

Can any body tell me how to fix this problem?