Add RRef Python Helper to launch function on the referenced object (#36619)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36619
With this PR, applications no longer need to create dedicated helpers
to run functions on the object referenced by an RRef. Instead,
`rref.rpc_sync().some_func()` will use `rpc_sync` to run `some_func`
on the owner of the RRef using the object referenced by the RRef.
Similar helpers for `rref.rpc_async().some_func()` and
`rref.remote().some_func()` are also added.
An alternative design is to expose PyRRef as RRefBase and then
implement everything in a new Python RRef class. However, the RRef
class cannot directly inherit from PyRRef/RRefBase, otherwise we
will need to let pyRemote* C++ functions to load RRef from Python
and return an RRef instance. It is possible to let RRef hold a
instance of PyRRef instead of inherit from it, but this does not
look like a elegant design, as we will have RRef holding PyRRef and
PyRRef holding the C++ RRef. Another alternative is to use dynamic
method loading, by installing member methods to PyRRef instances.
However, this would require different solutions to handle
RRef(data) and rpc.remote(...). Base on the above thinking, we
decided to go with the current implementation for simplicity and we
can also keep all RRef-related APIs in one place.
Test Plan: Imported from OSS
Differential Revision: D21028333
Pulled By: mrshenli
fbshipit-source-id: fe90f56ef7183d18874e357900093755e1601eb4
