I am looking for some more definitive and in depth information about record locking in Salesforce. I will admit I am quite a novice when it comes to the topic of record locking, and am not sure it is even going to solve my issue.

The reason I am investigating the feature is a difficult random bug that has been discovered. The code in question is a trigger that rolls up (lookup relationships hence code needed) some numeric values onto a parent, grandparent and great grandparent object. The value is being correctly calculated on the grandparent and great grandparent, but on rare occasions for reasons unknown the parent value is not calculated correctly. 99 times out of a 100 everything is calculated as expected.

The Salesforce Docs are quite bare of any real information.

There is a forum post which is 2.5 years old that as I read it has conflicting information. Anand claims the record locking is pessimistic, but cbarry9's quote from the unspecified manual is that other processes will wait, suggesting optimistic locking. FWIW I can not find that quote anywhere.

If I was to implement record locking, I would want to use optimistic locking.