[Zope] strange database read conflict error

Peter Bengtsson peterbe at gmail.com
Fri Aug 28 05:19:00 EDT 2009

The fact that the class is Products.Transience.Transience.Increaser
makes me suspect that you're using sessions and within the same
session you make too many read requests to the ZODB. When the load is
too high, after a certain amount of attempts Zope will say, "piss off!
...for a while and come back later". So it comes back later and works
Are you using lots of AJAX requests? That can sometimes cause read
conflict errors.

2009/8/28 Dragos Chirila <objectvalues at gmail.com>:
> Hello everyone,
> I have a question regarding a database read conflict error. I would
> appreciate any thoughts on this issue.
> I am using Zope, Python 2.3.7 with a ZEO server and 4
> clients for 6 months now. I have noticed that the event.log is filled
> with read conflict errors like the one below:
> 2009-08-28T10:29:26 INFO ZODB.Conflict database read conflict error
> (oid 0x09, class Products.Transience.Transience.Increaser) at
> /VirtualHostBase/http/metropotam.ro:80/metropotam/VirtualHostRoot/Opera/loc4769172835-Ateneul-Roman/
> (21 conflicts, of which 0 were unresolved, since startup at Thu Aug 27
> 15:25:02 2009)
> This URL of the object is
> http://metropotam.ro/Opera/loc4769172835-Ateneul-Roman . We have
> around 2000 objects of the same type and this is *the only one* that
> generates read conflict errors.
> I have tried a few things:
> 1.      Edit object and recatalog it
> 2.      Rename it
> 3.      Delete object, pack database, create a new object and then rename
> it to keep the URL alive
> 4.      checked the data.fs and got no errors (fstest.py)
> None of the above solved the problem; I still get a lot of conflicts.
> Is there a way to fix this? I found it very strange that I get
> conflicts only for this object and for no other of the same type, even
> in the same folder...
> Thank you,
> Dragos Chirila
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Peter Bengtsson,
work www.fry-it.com
home www.peterbe.com
hobby www.issuetrackerproduct.com
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