Google Colab/Jupyter Notebook fails with device_by_pid

[lfwa]

Google Colab/Jupyter Notebook fail when using device_by_pid=True.

Colab is able to retrieve PIDs on GPUs, however, these are separate from the main thread (not children of the main process). This means that even though we can see that the GPU is active with processes we cannot add them to active devices when using device_by_pid=True since they do not match any of the PIDs from either the main process or its children.