I’m generating a bunch of random data on the fly in an IterableDataset
loading the data in the main thread works just fine, And although setting num_workers=2 STILL works fine, the received data is uncorrupted and the training loop continues. But every now and then it throws this exception:
Exception ignored in: <function _MultiProcessingDataLoaderIter.__del__ at 0x7f5ae7bc4d40>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1328, in __del__
    self._shutdown_workers()
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1320, in _shutdown_workers
    if w.is_alive():
  File "/usr/lib/python3.7/multiprocessing/process.py", line 151, in is_alive
    assert self._parent_pid == os.getpid(), 'can only test a child process'
AssertionError: can only test a child process
Exception ignored in: <function _MultiProcessingDataLoaderIter.__del__ at 0x7f5ae7bc4d40>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1328, in __del__
    self._shutdown_workers()
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1320, in _shutdown_workers
    if w.is_alive():
  File "/usr/lib/python3.7/multiprocessing/process.py", line 151, in is_alive
    assert self._parent_pid == os.getpid(), 'can only test a child process'
AssertionError: can only test a child process
Exception ignored in: <function _MultiProcessingDataLoaderIter.__del__ at 0x7f5ae7bc4d40>
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1328, in __del__
    self._shutdown_workers()
  File "/usr/local/lib/python3.7/dist-packages/torch/utils/data/dataloader.py", line 1320, in _shutdown_workers
    if w.is_alive():
  File "/usr/lib/python3.7/multiprocessing/process.py", line 151, in is_alive
    assert self._parent_pid == os.getpid(), 'can only test a child process'
AssertionError: can only test a child process

Should I worry about this? and what do I have to do to stop it?