SIMPLE ANALYSIS OF EXCLUSIVE AND SHARED LOCK CONTENTION IN A DATABASE SYSTEM.

We consider a probabilistic model of locking in a database system in which an arriving transaction is blocked and lost when its lock requests conflict with the locks held by currently executing transactions. Both exclusive and shared locks are considered. We derive a simple asymptotic expression for the probability of blocking which is exact to order 1/N where N is the number of lockable items in the database. This expression reduces to one recently by Mitra and Weinberger for the special case where all locks are exclusive.