On 25 January 2011 20:29, Jacek Naruniec <[email protected]> wrote:
> Hi,
> I've got the problem, that I've seen on many sites, but none of them
> helped so far. My created webpage uses Django, Apache, Python2.7, PIL
> 1.2.7 (for Python 2.7) and mod_wsgi (for Python 2.7) running on
> Windows - all the latest releases. PIL and mod_wsgi was already
> compiled, i have'nt done it manually.
>
> When I try to use imaging library in plain python, everything is
> working, the _imaging library is successfully initialized. Sys.path is
> correct and points the PIL library.
>
> Using mod_wsgi the sys.path is also correct  (i've checked it by using
> application script in wsgi file), but still the "The _imaging C module
> is not installed" appears when when I try to use PIL.
> When i try to load _imaging library in the wsgi file, the log in the
> apache says "ImportError: DLL load failed" and that it cannot find the
> module.
>
> Does anyone know how to deal with this thing?

Am wandering if this is the same problem as is affecting psycopg2 and
potentially other C extension modules such as libcrypto.

That is, Python 2.6+ links to newer MS C runtime library that Apache
doesn't and C extension modules which are somehow dependent on the
newer MS C runtime library will not load properly.

Prior to Python 2.6 I believe psycopg2 was itself linking this MS C
runtime library and so was okay, but since that was no longer required
for Python 2.6+ or caused problems they stopped doing that on the
assumption that it would already be linked. In embedded system like
mod_wsgi you are dependent on the executing application, Apache in
this case, linking it as Python does, but Apache doesn't, thus the
problem.

I am a bit fuzzy on this and could have this wrong. If I am sort of
right, the solution may be to relink mod_wsgi.so for Windows with
dependency on new MS C runtime library. The library at issue seems to
be MSVCRT90, but I don't understand all the issues around it as don't
know Windows.

Can someone help me to understand this. Relevant links:

  http://archives.postgresql.org/psycopg/2011-01/msg00009.php
  http://psycopg.lighthouseapp.com/projects/62710/tickets/20
  
http://groups.google.com/group/modwsgi/browse_thread/thread/13b4a5faa962d77/dd4d6a03afbe16b6
  http://bugs.python.org/issue4120

The last one is perhaps the most informative about the change that
potentially caused the problem.

Graham

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