Features/PyPyStack

= PyPy Stack =

Summary
Fedora N+1 has an alternate Python 2 runtime and add-on module stack built using PyPy, an alternate implementation of the Python 2 language, featuring Just-in-Time compilation.

Owner

 * Name: Dave Malcolm


 * Email: 

Current status

 * Targeted release: Fedora 16?
 * Last updated: 2011-05-03
 * Percentage of completion: 30%

PyPy has been packaged within Fedora from Fedora 15 onwards, and is available via:

yum install pypy

See the package review)

We currently have PyPy-1.5

There is a tracker bug for the PyPy stack in Red Hat bugzilla.

Areas of uncertainty:
 * as of 1.4.1, support for .c extensions (using the CPython API) is still experimental (need to try some extensions and see what works)
 * 1.4.1 ships with a bytecode format similar to (but slightly different from) CPython 2.5.1. It's not yet clear to me what the anticipated rate of change to the bytecode format is.  If we build out a collection of pure-python extensions in RPM form (e.g. a pypy-django.rpm), with .pyc files, we don't want to be constantly having to rebuild them all as the precise bytecode format changes (even if we e.g. ported PEP 3147, we still ought to rebuild the RPMs)

Upstream work
 * working on improving the readability of the 6 million lines of autogenerated C code emitted by the build; I've sent patches upstream for this, but it's not yet finished.

Detailed Description
PyPy is a python interpreter written in a subset of python. The interpreter can have better memory use than CPython and speed is closing in on Cpython. The JIT'd version is faster than CPython in many benchmarks.

It is growing the ability to load CPython extension modules.

This feature is exploring the idea of shipping PyPy, and the scope is not yet clear, be it:
 * 1) just the core interpreter, or
 * 2) sharing pure-Python add-on modules with the system Python (but with split bytecode files), or
 * 3) a full, independent Python stack, but with just pure-Python add-on modules, or
 * 4) a full, independent Python stack, with both pure-Python and machine-code extension modules

Benefit to Fedora
PyPy is an innovative implementation of the Python language, but it can take an hour to build, requiring a powerful machine. By providing an easy way for people to install a PyPy stack, we continue to push Fedora as an excellent platform for Python developers.

Fedora aims to showcase the latest and greatest in Free/Open Source Software: PyPy is certainly innovative.

Fedora heavily uses Python, both within the operating system itself, and within the infrastructure used by the project. As PyPy becomes more mature we may eventually want to migrate from CPython to PyPy for some of these workloads.

Scope
An upstream guide to PyPy compatibility can be seen at https://bitbucket.org/pypy/compatibility/wiki/Home

Comments and Discussion

 * See Talk:Features/PyPyStack