Manual release of memory

[GunnarFarneback]

ONNXRunTime objects release their memory through a finalizer, which calls the CAPI.release function. As noted in the docstring, garbage collection should normally handle this automatically. However if you have a large GPU model you might have extreme GPU memory pressure without any CPU memory pressure at all, and the garbage collection won't be in any hurry to destroy your objects, which would release your GPU memory.

Obviously CAPI.release gives you the tool to handle this manually but it's quite clunky both to dip down into the C API, and to separately extract the api and session fields for the release call.

My proposal is to add a highlevel release function/method for InferenceSession. Thoughts?

[jw3126]

Yeah sounds like a useful addition. I think it should be a separate function from CAPI.release.