On 02:13 pm, stefan...@behnel.de wrote:
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.
Instances of classes don't refer to the module their class is defined
in. It seems more likely that the reason the module is garbage
collected is that there really is nothing which refers to it anymore.
The behavior of setting the attributes of a module being freed to None
has been in place for a long time, r85392 only restored it after a brief
absence.
Perhaps Cython itself should keep the modules alive that it wants kept
alive. Alternatively, if Cython owns the code that's running into the
zapped global, you could change it to not use globals.
Jean-Paul
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
