Friday, April 9, 2010

Using CPython extension modules with PyPy natively, or: PyPy can load .pyd files with CPyExt!

PyPy is now able to load and run CPython extension modules (i.e. .pyd and .so files) natively by using the new CPyExt subsystem. Unlike the solution presented in another blog post (where extension modules like numpy etc. were run on CPython and proxied through TCP), this solution does not require a running CPython anymore. We do not achieve full binary compatiblity yet (like Ironclad), but recompiling the extension is generally enough.

The only prerequisite is that the necessary functions of the C API of CPython are already implemented in PyPy. If you are a user or an author of a module and miss certain functions in PyPy, we invite you to implement them. Up until now, a lot of people (including a lot of new committers) have stepped up and implemented a few functions to get their favorite module running. See the end of this post for a list of names.

Regarding speed, we tried the following: even though there is a bit of overhead when running these modules, we could run the regular expression engine of CPython ( and execute the spambayes benchmark of the Unladen Swallow benchmark suite (cf. and experience a speedup: It became two times faster on pypy-c than with the built-in regular expression engine of PyPy. From Amdahl's Law it follows that the must run several times faster than the built-in engine.

Currently pursued modules include PIL and others. Distutils support is nearly ready. If you would like to participate or want information on how to use this new feature, come and join our IRC channel #pypy on freenode.

Amaury Forgeot d'Arc and Alexander Schremmer

Further CPyExt Contributors:

  • Alex Gaynor
  • Benjamin Peterson
  • Jean-Paul Calderone
  • Maciej Fijalkowski
  • Jan de Mooij
  • Lucian Branescu Mihaila
  • Andreas Stührk
  • Zooko Wilcox-O Hearn

PyPy on google open source blog


Bea Düring, from the PyPy team, wrote a post for google open source blog covering PyPy's 1.2 release. It's also the first public mention of the fact that google provided financial support for PyPy's 2.5 compatibility. Thanks!