[Zope3-Users] ZODB database conflict error

[Andreas Jung]

--On 24. Juni 2008 10:45:48 +0200 Gregor Giesen <grgi at fa.uni-tuebingen.de> 
wrote:

> Dear Andreas,
>
> thank your for your response.
>
>> > under heavy load of my zope application I got the following error:
>> >
>> >   WARNING ZopePublication Competing writes/reads at ... database
>> > conflict error (oid 0x03a272, class BTrees.OIBTree.OIBucket, serial
>> > this txn started with 0x0376b0db577575cc 2008-06-24 06:51:20.498163,
>> > serial currently committed 0x0376b0dc374f1244 2008-06-24
>> > 06:52:12.963017)
>> >
>> > This is due to many reads and writes (adding objects) to a BTreeFolder.
>> > So my questions are:
>> > 1. How can I increase the number of retries to resolve the conflict?
> I think this might be a quick workaround for my production instance.

At least in Zope 2 there is a variable "retry_max_count' within in the 
ZPublisher. Likely there is something similar within the Zope 3 publisher.
I would grep for "3" :-)

>
>> > 2. I think this might be a design problem of my application; should I
>> > use another backend for storing such data (sql, etc.)?
>
>> How about application specific conflict resolution (_p_resolveConflict()
>> hook)? How about using a nested folder structure in order to reduce the
>> number of conflicts?
> I thought about _p_resolveConflict, but I don't see how to catch up this
> conflict on my BTreeFolder derived class. Maybe I should give up the
> BTrees and use an ordinary container implementation?
>

This would make your problem even worser.

-aj

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