[Twisted-Python] SQLAlchemy and Twisted

[Chris Withers]

Doug Farrell wrote:
> 
> I’ve been doing some searching about how to get SQLAlchemy and Twisted 
> working together in a Twisted application. 

Short version: to be safe, anything that touches any SQLAlchemy-mapped 
object needs to be run in its own thread. Any query or access of an 
attribute of a mapped object may result in a blocking sql query. (aka: 
twisted doesn't play nice with orms)

> definitive answer. The most promising one I’ve run across concerns 
> running the SQLAlchemy queries in a separate process (rather than a 
> separate thread) and communicating the queries between the Twisted 
> application in one process and the SQLAlchemy application in another. 

That seems a little odd.
What would be the IPC?
How would the "sqlachemy application" be run?

> 1)      Would the SQLAlchemy process also be a Twisted application with 
> all the queries running as deferreds in the main thread, and blocking?

What do you men by "all the queries"?

> Thanks in advance for any help!

In my case, since most of the app I'm working on is "web requested" 
(either xmlrpc or http), I just agve up and used a good wsgi stack 
(repoze.bfg in my case) and munge other incoming requests into wsgi 
requests.

Twisted's wsgi server runs each request in its own thread, so be it.

cheers,

Chris