Does Custom C++ Class Release GIL?

Hi everyone, I’m trying the pytorch 1.5 new custom c++ class and want to release GIL during C++ execution to allow multithreading. However I found there is nowhere for me to insert py::call_guard<py::gil_scoped_release>() as we often do with c++ extensions.

So I wonder if pytorch releases GIL for custon c++ class by default? Thanks a lot!