What the warning is?

10/11/2022 17:28:42 - Despite set_to_none is set to False, opacus will set p.grad_sample and p.summed_grad to None due to non-trivial gradient accumulation behaviour

I ran almost the same two pieces of code, why does this warning appear in one, under what circumstances does this warning appear, does this warning have a big impact?


TL;DR: This warning has basically no impact.

It is about the behavior of optimizer.zero_grad(). The set_to_none argument only affects p.grad; p.grad_sample and p.summed_grad are never zeroed out and always set to None.

We switched the level from warning to debug, hence the potential difference between the two codebases?

yes, thank you very much