for shared-memory handles, use an atomic counter, instead of potentially colliding random numbers (#60978)
Summary:
These handles, used for shared-memory tensors, can collide.
E.g. see https://github.com/pytorch/pytorch/issues/60626#issuecomment-869919018
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60978
Reviewed By: mruberry
Differential Revision: D29479291
Pulled By: ezyang
fbshipit-source-id: 408ef1817768f007ad4795b286482809ea43467c
