On Jul 1, 2008, at 3:04 AM, Simon Wittber wrote:

>
> While stress testing my Pylons Web App, SQLAlchemy will occasionally
> throw the below exception.
>
> I've also seen the below exception on applications which have been
> running for a few weeks.
>
> Has anyone come across this before? I'm think it might be a threading
> issue, as it occurs intermittently, and is not always reproducible.

this means that at least one of the mappers is not fully compiled, but  
the "compiled" flag on a mapper which calls upon it is set.    This  
usually implies that the compilation process failed midway, which in  
all cases would throw an exception.   The compilation of mappers is  
synchronized such that whenever compile() is called, if any uncompiled  
mappers exist, they'll be compiled too before the method completes  
(and its all mutexed).    I'd inspect to see if compilation is failing  
and not being picked up, if theres a module with mappings in it which  
gets imported late in the game (which shouldn't be a problem), or if  
theres maybe some add_property() calls which might be occuring at an  
awkward stage of compilation (which also shouldn't be a problem).    
The only other possibility is that maybe the mapper structure is being  
accessed without the compile() step being called, though the  
construction of a Query compiles all mappers too.

One possibility would be to turn on sqlalchemy.orm INFO logging which  
will be pretty verbose about mappers compiling, so you'd be able to  
see exactly whats compiled before the exception gets thrown.


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