FAULT-TOLERANT DEADLOCK DETECTION IN DISTRIBUTED DATABASE SYSTEMS.

A new distributed deadlock detection algorithm (DDDA) is presented that uses both a global detector (GD) to detect global deadlocks and local detectors (LDs) to detect local deadlocks. The algorithms essentially identifies transaction-resource interactions that may cause global (Multisite) deadlocks. Such interactions are reported to the global controller, while the remaining interactions are handled locally. In order to make the DDDA fault-tolerant, three procedures have been incorporated to handle failures of the controller, of any local sites, and of communication links. This enhanced algorithm, called FTDDDA, improves the overall performance of the database system by improving the resiliency of the deadlock detection service.