thanks.
Looks that there’s a typo for SimpleQueue in the best practices.
from torch.multiprocessing.queues import SimpleQueue

we’ll get
ModuleNotFoundError: No module named 'torch.multiprocessing.queues'

Then I tried with
from torch.multiprocessing.queue import SimpleQueue
tens = SimpleQueue()

and the error message is:
    tens = SimpleQueue()
TypeError: __init__() missing 1 required keyword-only argument: 'ctx'

Just think memory copy of 400 720p (1080*720) RGB24 (3bytes) images is not big. In other words, even if we reduce the memory copy, it still does not resolve the issue since it is not the bottle neck.