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

[yacine chaouche]

Hi Dieter,

What part of what I said don't you understand ? I will try to make it
clearer here :
>
>   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...

Yes, when I posted the XMLRPC and strace message on the list I did not
know yet the publishing process and everything. So I thought that zope
just went crazy pretending to receive new requests. In reality, it was
the same request that was retried over and over again until no
exception was raised.

Once I understood the publishing process, I edited the publish.py file
to display a traceback  of every raised exception before retrying the
request. Thus, I could see that there were database conflict errors
that were raised.


> >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:

I do NOT use frames.

> >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.
>

That's what I am saying : in my code I need to use the session to
store objects. When I use the session, in my code, not in a plugin or
so, in my own code, I have errors.
When I do not use session, in my own code, I have no errors. This is
supposed to prove that the conflict error comes from the use of the
session object in my code. This is not supposed to prove that another
plugin is using it anyway...

Thanks,

Y.Chaouche

2007/2/2, Dieter Maurer <dieter at handshake.de>:
> 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
>