[Zope] strange database read conflict error

Fri Aug 28 07:49:06 EDT 2009

Ooops, paste it the wrong link below.... the URL of the object with
conflicts is http://metropotam.ro/Opera/loc4769172835-Ateneul-Roman/

On Fri, Aug 28, 2009 at 2:47 PM, Dragos Chirila<objectvalues at gmail.com> wrote:
> 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
>>>>> **   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
>>> _______________________________________________
>>> 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
>

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