You might also want to use the conflict resulution hook. The reason you don't see the Conflict Error exception is that it is caught and triggers a conflict resolution process.
On Tue, 4 Jul 2006, Jonathan wrote: > > ----- Original Message ----- > From: "Dennis Allison" <[EMAIL PROTECTED]> > To: "Jonathan" <[EMAIL PROTECTED]> > Cc: <firstname.lastname@example.org> > Sent: Tuesday, July 04, 2006 1:27 PM > Subject: Re: [Zope] Trying to trap ConflictError > > > > > > Johnathan, > > > > I have been lurking, following your thread, but not paying full > > attention. Excuse me if thes points have been made before. > > > > There are many long threads on Conflict Errors. You should read them. > > Note that there have been significant changes in management strategy > > beginning with Zope 2.9.X. > > > > A "Conflict Error" is not really an error in the usual sense; it is an > > indication of conflicting transactions in the ZODB, that is, transactions > > have violated the optimistic locking used by the ZODB. In general, > > Conflict Errors are resolved without problem. The resolution usually > > involves rolling back the older transaction and committing the newer > > transaction. When the actions associated with the rolled back transaction > > are not themselves fully transactional (for example, a file write) there > > can be unanticipated side effects. > > > > Your conflicts appear to be in Temporary Storage which is used for > > Session Variables. The version that ships with Zope is flexible and > > complex and, IMHO, overkill. Moreover, it has some unexpected properties, > > the most significant is that, even though session variables are stored in > > RAM, it occasionally uses the ZODB to manage session variable expiration. > > You can often decrease the number of session variable induced conflicts by > > increasing the lifetime of session variables. > > > > As both you and Andreas have recommended, I have started researching 'ZODB > Conflict Resolution' and if I come up with generic/reusable external method > application-level solution I will post it. > > By way of providing more information: > > I am not using sessions. I am using TemporaryStorage to hold small, > custom-made, short-lived image objects (the use case requires that each user > views a static image with a custom overlay, and that the user accesses this > customized image via an html img tag). The custom images are viewed only > once, and then can be deleted. Hence the use of TemporaryStorage (to > eliminate many disk writes and ZODB bloating). The image objects stored in > TemporaryStorage are never overwritten, edited etc (which is causing me some > confusion as to why the conflict errors are occurring), they are simply > created, stored in the TemporaryStorage folder (actually a BTreeFolder2 > folder contained within the TemporaryStorage folder) and then 2 minutes > later are deleted. I am guessing that the conflicts are occuring as the > TemporaryStorage is trying to delete old images while new image object 'add > requests' are piling up, but I have yet to determine the cause of the > conflict with 100% certainty (conflicts only occur under heavy loading, and > not always in the same place in the load testing). > > > Thanks again for everyone's help! > > Jonathan > -- _______________________________________________ Zope maillist - Zope@zope.org http://mail.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://mail.zope.org/mailman/listinfo/zope-announce http://mail.zope.org/mailman/listinfo/zope-dev )