[Zope] strange database read conflict error

Fri Aug 28 07:47:28 EDT 2009

All objects as the same type of this one that generates conflicts are
displayed using the same template that contains the same elements (js,
images, etc.).

I can access any object in the same folder
(http://metropotam.ro/Opera/) and I will get no read conflicts (e.g.
http://metropotam.ro/Opera/loc8982879061-Sala-Palatului/). I have
conflicts when I access this particular object
http://metropotam.ro/Opera/loc8982879061-Sala-Palatului/.

If the problem is related with some piece of code I can't find any
logical explanation for this behavior. ... or maybe I am looking in
the wrong place.

Also, told you before, I even erased the object from the Data.fs and
then packed it. Conflicts stopped. After I have created a new object
and rename it with the old id the conflicts showed up again...

Thanks,
Dragos

On Fri, Aug 28, 2009 at 2:37 PM, Peter Bengtsson<peterbe at gmail.com> wrote:
> 2009/8/28 Dragos Chirila <objectvalues at gmail.com>:
>> Peter,
>>
>> Than you for your response. Please find below a few things:
>>
>> - I give up using sessions in the website's front and years ago :)
>> There is only one page left that is using them, when u subscribe to
>> our newsletter but I don't think that this affects because is used
>> rarely
>>
> It might be used anyway. It'll be empty (except the
> subscribe-to-newsletter page) all the time but it might still be in
> use.
> I think there is always a REQUEST.SESSION object.
>
>> - I am using Yahoo Maps Ajax API to display maps; also some ajax calls
>> for our build in chat (only for logged users)
> That's unrelated. Yahoo! isn't using ZODB.
>
>>
>> So if the things above are causing read conflicts why only for this
>> particular object? There is nothing special or different with this
>> one...
>>
> It could be some other piece of code that tries to read from ZODB more
> than once and whatever it's trying to read might be something slow
> (slow for a computer).
>
> Have you tried running ZopeProfiler on your site to figure out if
> there are certain (ZO)DB related functions that are called either many
> many times or few but slow times.
>
>> Thanks again,
>> Dragos
>>
>> On Fri, Aug 28, 2009 at 12:19 PM, Peter Bengtsson<peterbe at gmail.com> wrote:
>>> 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
>>> fine.
>>> 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 2.8.9.1-final, 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
>>>> _______________________________________________
>>>> Zope maillist  -  Zope at zope.org
>>>> https://mail.zope.org/mailman/listinfo/zope
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>>>>  https://mail.zope.org/mailman/listinfo/zope-announce
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>>>>
>>>
>>>
>>>
>>> --
>>> Peter Bengtsson,
>>> work www.fry-it.com
>>> home www.peterbe.com
>>> hobby www.issuetrackerproduct.com
>>> fun crosstips.org
>>>
>>
>>
>>
>> --
>> Dragos Chirila
>> objectValues at gmail.com
>> (+4) 0722 395375
>> _______________________________________________
>> Zope maillist  -  Zope at zope.org
>> https://mail.zope.org/mailman/listinfo/zope
>> **   No cross posts or HTML encoding!  **
>> (Related lists -
>>  https://mail.zope.org/mailman/listinfo/zope-announce
>>  https://mail.zope.org/mailman/listinfo/zope-dev )
>>
>
>
>
> --
> Peter Bengtsson,
> work www.fry-it.com
> home www.peterbe.com
> hobby www.issuetrackerproduct.com
> fun crosstips.org
>

-- 
Dragos Chirila
objectValues at gmail.com
(+4) 0722 395375