[Zope-dev] Re: Conflict errors on BDBMinimal storage

[Tres Seaver]

Chris McDonough wrote:
> Hi Dr. Wagner,
> 
> 
>>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.
> 
> 
> Are you using ZEO for your session storage or are you using a local
> storage?  (You hint at it above but you don't actually say one way or
> the other.)
> 
> 
>>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 also need reliable sessioning for my own customers, so I am working
> towards fixing the issues I know about.  But the issues I know about may
> not be the same issues as those that you want fixed.  You can ensure
> your issues are addressed by devoting resources towards the problem, be
> that time+expertise or money or both.

I recently reworked Anthony Baxter's SQLSessions product for a 
consulting customer, essentially modernizing the code and making it 
compliant with the new Sessions interface (I dropped the bits which do 
the work currently done by BrowserIDManager).  It took me about six 
hours or so, including writing unit tests.  Unfortunately, I don't have 
access to that code, due to the nature of the consulting arrangement.

What I would like to do is revisit the effort, using the new 
PluginRegistry code released as part of the PluggableAuthService 
release;  I am, however, pretty well booked up for the next few weeks. 
I would be glad to advise anybody who felt called to take on such an 
effort, however.

Tres.
-- 
===============================================================
Tres Seaver                                tseaver at zope.com
Zope Corporation      "Zope Dealers"       http://www.zope.com