example code error with multi-gpu?

[sunruina2]

GPU available: True, used: True TPU available: False, using: 0 TPU cores LOCAL_RANK: 0 - CUDA_VISIBLE_DEVICES: [0,1,2,3] Traceback (most recent call last): File "train.py", line 117, in trainer.fit(model, train_loader) File "/opt/conda/lib/python3.6/site-packages/pytorch_lightning/trainer/trainer.py", line 445, in fit results = self.accelerator_backend.train() File "/opt/conda/lib/python3.6/site-packages/pytorch_lightning/accelerators/ddp_spawn_accelerator.py", line 74, in train mp.spawn(self.ddp_train, nprocs=self.nprocs, args=(self.mp_queue, model,)) File "/opt/conda/lib/python3.6/site-packages/torch/multiprocessing/spawn.py", line 199, in spawn return start_processes(fn, args, nprocs, join, daemon, start_method='spawn') File "/opt/conda/lib/python3.6/site-packages/torch/multiprocessing/spawn.py", line 148, in start_processes process.start() File "/opt/conda/lib/python3.6/multiprocessing/process.py", line 105, in start self._popen = self._Popen(self) File "/opt/conda/lib/python3.6/multiprocessing/context.py", line 284, in _Popen return Popen(process_obj) File "/opt/conda/lib/python3.6/multiprocessing/popen_spawn_posix.py", line 32, in init super().init(process_obj) File "/opt/conda/lib/python3.6/multiprocessing/popen_fork.py", line 19, in init self._launch(process_obj) File "/opt/conda/lib/python3.6/multiprocessing/popen_spawn_posix.py", line 47, in _launch reduction.dump(process_obj, fp) File "/opt/conda/lib/python3.6/multiprocessing/reduction.py", line 60, in dump ForkingPickler(file, protocol).dump(obj) File "/opt/conda/lib/python3.6/enum.py", line 46, in _break_on_call_reduce raise TypeError('%r cannot be pickled' % self) TypeError: <Resample.BILINEAR: 1> cannot be pickled