Add torch::deploy, an embedded torch-python interpreter (#50458)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50458
libinterpreter.so contains a frozen python distribution including
torch-python bindings.
Freezing refers to serializing bytecode of python standard library modules as
well as the torch python library and embedding them in the library code. This
library can then be dlopened multiple times in one process context, each
interpreter having its own python state and GIL. In addition, each python
environment is sealed off from the filesystem and can only import the frozen
modules included in the distribution.
This change relies on newly added frozenpython, a cpython 3.8.6 fork built for this purpose. Frozenpython provides libpython3.8-frozen.a which
contains frozen bytecode and object code for the python standard library.
Building on top of frozen python, the frozen torch-python bindings are added in
this diff, providing each embedded interpreter with a copy of the torch
bindings. Each interpreter is intended to share one instance of libtorch and
the underlying tensor libraries.
Known issues
- Autograd is not expected to work with the embedded interpreter currently, as it manages
its own python interactions and needs to coordinate with the duplicated python
states in each of the interpreters.
- Distributed and cuda stuff is disabled in libinterpreter.so build, needs to be revisited
- __file__ is not supported in the context of embedded python since there are no
files for the underlying library modules.
using __file__
- __version__ is not properly supported in the embedded torch-python, just a
workaround for now
Test Plan: tested locally and on CI with cmake and buck builds running torch::deploy interpreter_test
Reviewed By: ailzhang
Differential Revision: D25850783
fbshipit-source-id: a4656377caff25b73913daae7ae2f88bcab8fd88
