Benjamin Peterson, 22.10.2010 16:17:
2010/10/22 Stefan Behnel:
Benjamin Peterson, 22.10.2010 16:03:
2010/10/22 Stefan Behnel:
since SVN rev. 85392, Cython's installation fails on the py3k branch with
a
weird globals error. I think it is related to some sys.modules magic that
we
do in order to support running Cython in Python 3 using lib2to3.
Basically, what we do is, we import some parts of Cython at the beginning
that are Py3 clean, specifically some distutils build_ext replacement for
building Cython modules. Then we start up distutils, which first runs
lib2to3 on Cython's sources to convert them into Py3 code. When it then
gets
to building the binary modules, we remove all Cython modules and packages
from sys.modules and reimport their 2to3-ed sources so that we can run
the
complete compiler during the installation (to bootstrap parts of Cython
into binary modules).
Since the above revision, this process bails out with an error when
accessing "os.path" because "os" is None. The "os" module is imported
globally in our early-imported build_ext module, more or less like this:
import os
from distutils.command import build_ext as _build_ext
class build_ext(_build_ext.build_ext):
def build_extensions(self):
print(os) # prints None!
I suspect that the fact that we remove the modules from sys.modules
somehow
triggers the cleanup of these modules while there are still objects from
these modules alive that refer to their globals. So, what I think is
happening is that the module cleanup sets the module's globals to None
before the objects from that module that refer to these globals have
actually gone out of scope.
Could someone (benjamin?) please look into this?
Is this broken before 2.7, ie 2.6 and 2.6?
I can't tell. Py2 doesn't need 2to3, so we don't unload the modules there.
What about 3.1.0 then?
The 3.1.2 release was fine, but the current 3.1 SVN branch is not. I assume
you have applied the change there, too?
py3.1 branch:
https://sage.math.washington.edu:8091/hudson/job/cython-devel-build-py31/524/console
py3k branch:
https://sage.math.washington.edu:8091/hudson/job/cython-devel-build-py3k/613/console
We have our CI tests running against both branches, as well as all Py2
branches starting from 2.3. That's how I spotted it.
Stefan
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