I am running open source code 3 inside docker environment.  It is quite strange to encounter the error inside the docker containers, while others run on PC do not encounter the issue.
Exception ignored in: <function _MultiProcessingDataLoaderIter.__del__ at 0x7fae49c835f0>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1101, in __del__
    self._shutdown_workers()
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1075, in _shutdown_workers
    w.join(timeout=_utils.MP_STATUS_CHECK_INTERVAL)
  File "/usr/lib/python3.7/multiprocessing/process.py", line 138, in join
    assert self._parent_pid == os.getpid(), 'can only join a child process'
AssertionError: can only join a child process

The parameters to create a container
docker run --shm-size 64G --gpus all -d -v /xxx:/xxx --network host --name xxx_name --cpus 40 xxx_image