OS X and the mystery bits
Sometimes I have to learn a lesson over and over again before I get a glimmer of what’s going on. I spent some time again today trying to get the MySQL client library module for Python working. I need it to be able to talk w/ a MySQL database for an online store. I’d rather use PostgreSQL but in this case, I don’t have a choice.
I downloaded MySQL OS X package and ran the installation program. It did what it was supposed to – install the software under /usr/local. The MySQL client runs and all seems right with the world. I download and install the MySQL Python client module and it builds as expected. But when I try to run Django, I get this error:
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: dynamic module does not define init function (init_mysql)
Grumble, grumble, grumble.
I try to load the MySQL Python module directly:
peter@drag:~> python Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import _mysql Traceback (most recent call last): File "", line 1, in File "build/bdist.macosx-10.6-universal/egg/_mysql.py", line 7, in File "build/bdist.macosx-10.6-universal/egg/_mysql.py", line 6, in __bootstrap__ ImportError: dynamic module does not define init function (init_mysql)
I checked the build output. Checked the install output. Everything looks fine. This should work. Searching the web doesn’t help much since the references I find are from 2007 and 2008. The patches that they describe have already been incorporated into the MySQL Python module.
About this time, I realize that I’ve solved this problem before. It has to do with bits. I run:
peter@drag:~> python Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import platform >>> platform.architecture() ('64bit', '') >>>
I look at the original MySQL disk image that I downloaded and see that its a 32bit application. Mixing a 32bit dynamic library with a 64bit executable doesn’t work.
After downloading the 64bit MySQL disk image, installing it and rebuilding the MySQL Python module, everything works. Now its on to writing code for the online store. Yea.