[Twisted-Python] Using sqlalchemy in twisted.

Peter Cai newptcai at gmail.com
Wed Mar 11 22:05:29 MDT 2009


Hi,
I've read some mails in this list that recommend use sqlalchemy in separate
processes.

But if u use multiprocessing which provides only synchronous API, doesn't
you have to use deferToThread also?

Another way would be using "twisted.internet.protocol.ProcessProtocol",
which use pipes.  But can we pass SA Objects through pipes?

If you can write a little code to describe how you use multiprocessing,  I
will be very thankful!

On Wed, Mar 11, 2009 at 1:22 AM, luper rouch <luper.rouch at gmail.com> wrote:

> I would recommend sandboxing Twisted code in another process when used
> in conjunction with synchronous code (sqlalchemy, GUI, etc...). This
> proved quite simple in my project, using the multiprocessing module
> [1], and avoided me lots of headaches since.
>
> This way I don't mix coding styles everywhere using deferToThread(),
> nor do I care about threads safety madness.
>
> Now I'm not sure if this could apply to your situation, but if like me
> you're just routing the SA traffic through Twisted (just guessing as
> you mentioned deferToThread()), have not so much interaction between
> Twisted and the synchronous code part, it might be a better solution
> than writing wrappers / limiting your usage of the synchronous code.
>
> Luper
>
> [1]http://code.google.com/p/python-multiprocessing/ (now part of python
> 2.6)
>
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