[Zope-DB] ZODB/ZEO question.

Willadsens aagg at comcast.net
Tue Apr 5 08:55:46 EDT 2005

Chris Withers wrote:

> Willadsens wrote:
>>> Apparently, two concurrent transactions try to modify the
>>> root object.
>> Correct, and very intentional.
> Why? I'd suggest an architecture change that removes the root as a 
> hotspot.

Chris, please help me understand how this makes a difference in ZODB.
I currently store a persistent list in the ZODB as follows:
root[db_name] = some list

Are you suggesting that I store it in some other, nested dictionary off 
of root, such as:
root[db_name][listname] = some list

Can you give a simple example of what you mean? because, it seems that 
in eitehr case, I am hittting the same persistent resource, and this 
would not solve my problem.

The whole appeal of the ZODB and the persistence class is the ability to 
use Python data structures _normally_. I am hoping to accomplish this 
without adding an ugly layer of complexity.

>> The current question is: semaphore or trap error and retry? Chris 
>> suggested a retry, and said the semaphore is not necessary.
> If you need a semaphore for this, it doesn't need to be persistent. 
> Just use a lok from Python's threading module...

These are good suggestions. Thank you, Dieter and Chris.


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