Enabling CPython multi-core parallelism via subinterpreters.
This repo is for tracking the effort and as a place to keep any tooling.
From my python-ideas post (June 2015):
Python's multi-core story is murky at best. Not only can we be more
clear on the matter, we can improve Python's support. The result of any
effort must make multi-core (and concurrency) support in Python obvious,
unmistakable, and undeniable (and keep it Pythonic).
The goal of this project is to do just that, by using the existing subinterpreter C-API.
The minimal multi-core solution will involve:
- resolving existing bugs and blockers
- exposing the existing support (from C-API) in a stdlib module
- adding a mechanism to safely "share" basic immutable objects between interpreters
- no longer sharing the GIL between interpreters
Once a minimal solution is in place we can expand from there.
At a high level, we're doing the following concrete tasks:
- PEP 554 (Multiple Interpreters in the Stdlib)
- improve interpreter isolation (especially by moving fields from
PyRuntimeStatetoPyInterpreterState)
- no significant impact on single-threaded performance
- maintain backward compatibility (C-API, etc.)
- (pseudo-)compatibility with multiprocessing/threading/concurrent.futures APIs
- a multi-core concurrency model/approach that fits our brains
- Python APIs
- supportable on other Python implementations
- slow progress
- high level of community excitement
- increasing number of collaborators
- phase 1 ("minimal solution") completion getting closer
- still hopeful for Python 3.9
- PEP 554 low-level implementation mostly complete
- currently working on moving globals to runtime/interpreter state (or removing them)
- will take a while (started with ~1500 global variables)
- next up is making memory allocators per-interpreter (and then the GIL itself)
This project wouldn't be what it is without the help of these great people:
- @ncoghlan - inspired the solution; PEP 432
- @encukou - better subinterpreter support in extension modules
- @vstinner - all sorts of runtime stuff
- @emilyemorehouse - reviews & sanity checks
- @nanjekyejoannah - C-API; PEP 554 high-level module
- @eduardo-elizondo (Facebook/Instagram) - extension modules; globals
- @vsajip - globals
- many others
There are many ways to contribute to this project. Aside from the main technical work in the CPython runtime, there are also a number of jobs that need to be done that are less expert-related and even (somewhat) non-technical. All of it is important and anyone interested in helping is welcome!
Keep in mind that this project/repo is actually just a tool to organize the effort. The actual work is done on bugs.python.org, github.com/python/cpython, and the python-dev mailing list.
Also note that contacting @ericsnowcurrently directly is fine, but you might get a faster response through those other channels or through the issue tracker here. :)
For more information see the wiki page.