importing xformers.ops implicitly initializes CUDA context

[function2-llx]

Currently, importing xformers.ops will implicitly initializes CUDA context. This has an unpleasant effect that we cannot use the "fork" multi-processing method.

The line of code that initializes CUDA context is as follows:

xformers/xformers/__init__.py

Line 52 in f663712

if torch.cuda.get_device_capability("cuda") < (8, 0):

[danthe3rd]

Hi,
Thanks for reporting this issue. Unfortunately it might be more effort than just this line, as we check for device capabilities in multiple places as well...
@fmassa @bottler any idea?

[bottler]

Fixing this would be good for cutting import times.

We need _is_triton_available to be only called when a public function is called, not at import time of public modules. I think we could do that.

[bottler]

It's possible that the commit 737c2e6 just now will fix this.