[Zope-dev] Conflict errors on BDBMinimal storage

[Dr. Thomas Wagner]

Hi Chris, hi folks.

thanks for the hint with minimal storage. however the same problem 
occurs with filestorage and is even worse.

we know very well, that we cannot avoid the appearance of conflict 
errors in particular with zeo, and we understand what causes them.

what wonders us is, that we find some contributions about this errors in 
the mailing lists, but no one seems to have a real problem with it. but 
we have! we are not worried about some errors appearing in a log, but we 
are using plone2 witch currently 30 concurrent authenticated users, so 
that this error occurs permanently, thus decreasing system performance 
due to several retries and moreover leading to very frequent nasty 
'POS.Exception Errors' in the browser, whenever four successive tries 
fail (almost every 100. request).

this is not acceptable, and i  wonder wheter there are any plone sites 
with more than a handful of authenticated users that experience the same 
problem.  we found that one (there are more) product responsible for it 
is the placeless translation service, which heavily writes to the session.

so we desperately need a solution for this problem, maybe uncouple the 
session of the locking mechanism or whatever, and this should be a 
problem that should be addressed by the core team. because this is a 
strong reason (and so far the only one) to avoid using zope/plone in a 
large user environment.

i hope some of the community sees the importance of this.

Regards
Thomas
 


>On Thu, 2004-05-13 at 05:23, Gerhard Schmidt wrote:
>  
>
>>Hi,
>>
>>whe are running portal unter zope2.7 with one zeo server and six frontend 
>>application servers. 
>>
>>I have set up zeo to server two storages
>>
>><filestorage main>
>>  path $INSTANCE_HOME/var/Data.fs
>></filestorage>
>>
>><minimalstorage temp>
>>  envdir $INSTANCE_HOME/var/session
>></minimalstorage>
>>
>>temp should provide an shared session. But when is set up the frontends 
>>to use temp as /temp_folder, we see many  ZODB conflict errors. The 
>>performance decreases and PosErrors appear quite often. 
>>    
>>
>
>BDBMininalStorage is no longer maintained and doesn't do any "conflict
>resolution".  Even though you'll need to pack frequently, you might want
>to try a FileStorage instead.
>
>Regardless, using ZEO will presumably always generate more conflict
>errors than using a "local" ZODB because the commit time is longer, and
>thus there's a better chance that two threads will be committing at the
>same time.
>
>- C
>
>
>  
>