> On Feb 22, 2015, at 10:09 PM, Ed Rahn <edsr...@gmail.com> wrote:
>
> I am occassionally and randomly getting a DetachedInstanceError when I try to
> access an object atttribute that is a reference. I will run this several
> thousand times and only get it twice. What I don't understand is I use the
> same exact base query, which is where the reference takes place, and it works
> fine. Then I call a function which does some calculations and then it creeps
> up. I don't close or commit the sesssion or anything weird.
>
> I did some research about this error, and some possible causes are duplicate
> sessions and using the default expire_on_commit. I've updated my call to
> session_maker to set expire_on_commit to False. And although I'm using
> MultiProcessing and creating a new scopped_session for each instance,
Not sure if this is a factor but if you are using multiprocessing it's
essential that you use new connections in the child fork. I added a new
section
http://docs.sqlalchemy.org/en/rel_0_9/core/pooling.html#using-connection-pools-with-multiprocessing
detailing some approaches to handling this.
> the only conclusion I can come to is this is causing the problem, but why
> only occassionally? The retreival of the problem object and all the proceding
> function calls happen in the same process, so I'm stuck looking for other
> solutions.
>
> I've tried calling session.merge() on the problem object and I have the same
> problem.
>
> So I'm wondering what could also cause a problem like this or what shouldn't
> I be doing that would cause this?
>
> There is a lot of code and it isn't anywhere public and I havn't been able to
> make a minimial example, but this is a snippet of the problem code:
> https://gist.github.com/edrahn/ec4b1b757313a0f5c3c3
>
> And here is one of the tracebacks:
> https://gist.github.com/edrahn/bcc1aba82b3c70168a43
>
> Let mw know if you need anything else!
>
>
> Thanks.
> --
> Ed Rahn <edsr...@gmail.com>
>
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