ZPublisher.Conflict ConflictError

[rfernandes]

Hi.

I have a plone 3.1.2 (zeo) and since a few months ago my plone is getting a increase rate of ZPublisher.Conflict ConflictError 's.
I even stopped instance 2 which wasn't being used but the conflicts continue to arise.
After stoping instance 2 i didn't had any more conflicts during the instance 1 start but in instance one i get often the following error:

2008-06-23T14:00:49 INFO ZPublisher.Conflict ConflictError at /nai/portal_factory/Ploneboard/ploneboard.2008-06-23.0266525396/base_edit: database conflict error (oid 0x046cbb, class BTrees._OOBTree.OOBTree, serial this txn started with 0x0376acac7b982499 2008-06-23 13:00:28.967416, serial currently committed 0x0376acacccf740cc 2008-06-23 13:00:48.038867) (39 conflicts (0 unresolved) since startup at Thu Jun 19 13:35:03 2008)

How can i reduce the conflicts? Sometimes when 2 or 3 users press save almost simultaneously they get an error.

Thanks in advance,
Rui

[ajung]

--On 23. Juni 2008 06:06:57 -0700 rfernandes <[hidden email]> wrote:

>
> Hi.
>
> I have a plone 3.1.2 (zeo) and since a few months ago my plone is getting
> a increase rate of ZPublisher.Conflict ConflictError 's.
> I even stopped instance 2 which wasn't being used but the conflicts
> continue to arise.
> After stoping instance 2 i didn't had any more conflicts during the
> instance 1 start but in instance one i get often the following error:
>
> 2008-06-23T14:00:49 INFO ZPublisher.Conflict ConflictError at
> /nai/portal_factory/Ploneboard/ploneboard.2008-06-23.0266525396/base_edit:
> database conflict error (oid 0x046cbb, class BTrees._OOBTree.OOBTree,
> serial this txn started with 0x0376acac7b982499 2008-06-23
> 13:00:28.967416, serial currently committed 0x0376acacccf740cc 2008-06-23
> 13:00:48.038867) (39 conflicts (0 unresolved) since startup at Thu Jun 19
> 13:35:03 2008)
>
> How can i reduce the conflicts? Sometimes when 2 or 3 users press save
> almost simultaneously they get an error.
>

The first thing is to figure out the objects where the conflict errors
occur. See

<http://www.zopelabs.com/cookbook/1020679104>

-aj

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[Dieter Maurer]

rfernandes wrote at 2008-6-23 06:06 -0700:

> ...
>2008-06-23T14:00:49 INFO ZPublisher.Conflict ConflictError at
>/nai/portal_factory/Ploneboard/ploneboard.2008-06-23.0266525396/base_edit:
>database conflict error (oid 0x046cbb, class BTrees._OOBTree.OOBTree, serial
>this txn started with 0x0376acac7b982499 2008-06-23 13:00:28.967416, serial
>currently committed 0x0376acacccf740cc 2008-06-23 13:00:48.038867) (39
>conflicts (0 unresolved) since startup at Thu Jun 19 13:35:03 2008)
>
>How can i reduce the conflicts? Sometimes when 2 or 3 users press save
>almost simultaneously they get an error.

"ConflictError"s happen when two transactions concurrently
try to modify the same object.

In the case above, this object has been an "OOBTree" instance,
the one with object id "0x46cbb". It has been read at 13:00:28
but a concurrent transaction has changed it a 13:00:48,
therefore the current transaction cannot write it now (probably at
13:00:49 in the above used timezone).


Occasional "ConflictError"s are normal -- not to worry about.
Only when they occur with higher frequency, they may pose
a problem (as the probability increases that they cannot be resolved).
39 conflicts in 25 minutes may start to get troubling....


The "OOBTree" above is probably part of a catalog.
A "QueueCatalog" may help to reduce catalog related conflicts.
It delays cataloguing and lets perform it in a separate thread/process
such that catalog objects are only modified by a single transaction
(no more concurrent modifications). Disadvantage: Your indexes
are behind the world of objects as their updates is delayed.



--
Dieter

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