[Zope-dev] Session Errors

[Toby Dickenson]

On Saturday 15 March 2003 5:40 pm, Chris McDonough wrote:

> - The second is an unidentified (yet) bug in TemporaryStorage. 

As a cause of the KeyError exception? Could be.... I have seen equivalent 
exceptions with plain FileStorage in applications that do not use sessions, 
so I suspect there might be a hard-to-hit zodb bug that can cause this too. 
(In FileStorage the equivalent exception is POSKeyError, a subclass of 
KeyError)

> If I find and fix the TemporaryStorage bug I will let you know. In the
> meantime, you can probably work around this by using a different
> non-undoing storage to put your session data in (e.g. Berkeley, or maybe
> DirectoryStorage?).

It would be interesting to hear if this exception is repeatable with the 
session state stored in a FileStorage too.

> > > You may see many more conflicts with this running.  But maybe the data
> > > structures will not become desynchronized.
> >
> > You weren't kidding about the increase in conflict errors.

Read conflicts occur if a change is committed in between the start of a 
transaction, and the transaction needing to load the object. A workaround to 
reduce the number of read conflicts is to touch the objects that are likely 
to change early in the transaction.


-- 
Toby Dickenson
http://www.geminidataloggers.com/people/tdickenson