[Zope] Florent Guillaume's database Conflict Error on session objects patch not working ?

Dieter Maurer dieter at handshake.de
Fri Feb 2 17:39:10 EST 2007


yacine chaouche wrote at 2007-2-2 14:39 +0100:
> ...
> As discussed  here :
> http://mail.zope.org/pipermail/zope/2007-January/170151.html
> and continued here :
> http://mail.zope.org/pipermail/zope/2007-January/170156.html
> 
> I am experiencing issues regarding a database ConflictError on session objects.

Hm, I have issues with your problem descriptions...

  The referenced links above do not refer to conflict errors
  but to "XMLRPC and strace".

  Then, too, I had great difficulties to understand your problem...

> ...
>It is not a ReadConflictError, nor a
>WriteConflictError. It is a "ConflictError: database conflict error".

A "ConflictError" is in fact a "WriteConflictError".

>I am aware that conflicts occure up to 20% of the time, but in my case
>it is almost 100% in this specific situation !

You can easily achieve almost sure conflicts.

We did once with a frame based solution:

   All frames in a frameset accessed the session and tried
   to store some information in it.

   As the browser requested the frames concurrently, there
   was a very high probablity for conflicts.

In our case, there was no real need for most of the frames
to access the session. Removing the unnecessary accesses removed
the problem.

But, if the frames had a real need to store something in the
session, we would have to use persistent subobjects in the session
to separate the access of the various frames into different objects.

>If I do not use the session object in my code, I have no errors at all
>and everything just goes fine.

Then, you are using some add-on component that *is* using the session
object.

If the session is not used, there will be no session
related conflict error.

>Any idea on how to debug this ? Florent, maybe ?  someone help me ! I
>am stuck on this for 2 weeks now.

You could try to delete "/temp_folder/session_data" temporarily
(it will be recreated on the next Zope startup) to find out
which component does use sessions.



-- 
Dieter


More information about the Zope mailing list