Dynamic deadlock avoidance: a prototype

Abstract

In this paper, we describe a prototype of an expert system software advisor for the deadlock treatment of a lock manager in a database system. The software advisor, called EAGLE (External Advisor for Granting Locks Expertly), maintains a record of lock requests and lock status within a simulated database management system environment processing transactions. The sequence of lock information is held as a script(s). EAGLE matches lock request sequences against previously stored scripts. As EAGLE gains experience of lock event sequences leading to deadlock, it recognises patterns which have led to deadlock, and dynamically objects to the further granting of locks which would repeat a previous deadlock-inducing sequence of locks. This paper describes the design of EAGLE, EAGLE's dynamic deadlock avoidance (DDA) technique, and presents preliminary results from the EAGLE prototype compared with a simulated Deadlock Detection and Resolution technique (DLD).