ImportError with pickle (Python 2.7.9), possibly platform dependent

[Peter Otten]

Ben Sizer wrote:

> On Thursday, 30 April 2015 01:45:05 UTC+1, Chris Angelico  wrote:
>> On Thu, Apr 30, 2015 at 2:01 AM, Ben Sizer wrote:
>> > 1) There clearly is a module named OMDBMap, and it's importable - it's
>> > there in the 2nd line of the traceback.
>> >
>> > Does anybody have any suggestions on how I can go about debugging this?
>> > Or refactoring it to avoid whatever is happening here?
>> 
>> Are you half way through importing it when this load() call happens?
>> That might cause some issues.
> 
> No, we already imported OMDBMap at the top of OMDBSetup.
> 
>> Has your current directory been changed anywhere in there?
> 
> Good question. It turns out that the current directory seems to be $HOME
> when loading, but is the script directory during saving. This will be
> because the Linux server is running under mod_wsgi, whereas we run the
> save script in-place. Our Windows and Mac tests run via Flask's built-in
> server so the working directory is likely to be the same whether we're
> running the script that does pickle.dump or the whole app that does
> pickle.load.
> 
>> What happens if you catch this exception and print out sys.modules at
>> that point?
> 
> Another good question, and this gives us the answer. The module lists are
> quite different, as I'd expect because the load happens in the context of
> the full application whereas the dump happens as a standalone script. But
> literally every module that is in the 'before dump' list is in the 'before
> load' list - except OMDBMap. Like the error says! What /is/ in the 'before
> load' list however is "my_wsgi_app.OMDBMap". The module has been imported,
> but the pickle algorithm is unable to reconcile the module in the WSGI
> app's namespace with the module referenced in the pickle file.
> 
> So... I don't know how to fix this, but I do now know why it fails, and I
> have a satisfactory answer for why it is acting differently on the Linux
> server (and that is just because that is the only one running under WSGI).
> Two out of three isn't bad!

How about moving OMDBMap.py into the parent folder of my_wsgi_app.__file__ 
or any other folder in sys.path?