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Apr 27, 2018
in Post
2 min read

How to ignore the annoying Cython warnings in PyPy 6.0

Originally published on the PyPy blog.

If you install any Cython-based module in PyPy 6.0.0, it is very likely that you get a warning like this:

>>>> import numpy
/data/extra/pypy/6.0.0/site-packages/numpy/random/__init__.py:99: UserWarning: __builtin__.type size changed, may indicate binary incompatibility. Expected 888, got 408
  from .mtrand import *

The TL;DR version is: the warning is a false alarm, and you can hide it by doing:

$ pypy -m pip install pypy-fix-cython-warning

The package does not contain any module, only a .pth file which installs a warning filter at startup.

Technical details

This happens because whenever Cython compiles a pyx file, it generates C code which does a sanity check on the C size of PyType_Type. PyPy versions up to 5.10 are buggy and report the incorrect size, so Cython includes a workaround to compare it with the incorrect value, when on PyPy.

PyPy 6 fixed the bug and now PyType_Type reports the correct size; however, Cython still tries to compare it with the old, buggy value, so it (wrongly) emits the warning.

Cython 0.28.2 includes a fix for it, so that C files generated by it no longer emit the warning. However, most packages are distributed with pre-cythonized C files. For example, numpy-1.14.2.zip include C files which were generated by Cython 0.26.1: if you compile it you still get the warning, even if you locally installed a newer version of Cython.

Oct 30, 2017
in Post
8 min read

How to make your code 80 times faster

Originally published on the PyPy blog.

I often hear people who are happy because PyPy makes their code 2 times faster or so. Here is a short personal story which shows PyPy can go well beyond that.

Oct 18, 2017
in Post
4 min read

(Cape of) Good Hope for PyPy

Originally published on the PyPy blog.

Jul 26, 2017
in Post
1 min read

Binary wheels for PyPy

Originally published on the PyPy blog.

Hi,

this is a short blog post, just to announce the existence of this Github repository, which contains binary PyPy wheels for some selected packages. The availability of binary wheels means that you can install the packages much more quickly, without having to wait for compilation.

Sep 26, 2012
in Post
3 min read

Py3k status update #6

Originally published on the PyPy blog.

This is the sixth status update about our work on the py3k branch, which we
can work on thanks to all of the people who donated to the py3k proposal.

Jul 10, 2012
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2 min read

Py3k status update #5

Originally published on the PyPy blog.

This is the fifth status update about our work on the py3k branch, which we
can work on thanks to all of the people who donated to the py3k proposal.

Jun 5, 2012
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2 min read

Py3k status update #4

Originally published on the PyPy blog.

This is the fourth status update about our work on the py3k branch, which we
can work on thanks to all of the people who donated to the py3k proposal.

Apr 6, 2012
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3 min read

Py3k status update #3

Originally published on the PyPy blog.

This is the third status update about my work on the py3k branch, which I can work on thanks to all of the people who donated to the py3k proposal.

Mar 1, 2012
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Py3k status update #2

Originally published on the PyPy blog.

This is the second status update about my work on the py3k branch, which I can work on thanks to all of the people who donated to the py3k proposal.

Feb 16, 2012
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2 min read

Py3k status update

Originally published on the PyPy blog.

Thank to all the people who donated to the py3k proposal, we managed to collect enough money to start to work on the first step. This is a quick summary of what I did since I began working on this.