What does 'torch._C._log_api_usage_once' do?

1

For example it is used here,

def _log_api_usage(identifier: str):
    """
    Internal function used to log the usage of different detectron2 components
    inside facebook's infra.
    """
    torch._C._log_api_usage_once("detectron2." + identifier)

But why would I need to log these and where does it log and what is the usage of these logs?

2

This is strictly debugging and, as the comment indicates, quite likely most of the usage is inside facebook. If you set the environment variable

PYTORCH_API_USAGE_STDERR=1

you can see that PyTorch records “which parts of PyTorch are involved”, quite likely to give you a rough idea where to look (and whom to have look) if something unexpected happens.
PyTorch has grown quite huge with lots of moving bits and sometimes unexpected interactions, so having a quick idea of how to narrow things down or compare high-level processing flow between versions is a debug help.

Bast regards

Thomas

4 Likes
3

Thank you for the great answer!