Two-phase deadlock detection algorithm

A deadlock detection algorithm utilizing a transaction-wait-for (TWF) graph is presented. It is a fully distributed algorithm which allows multiple outstanding requests. The proposed algorithm can achieve improved overall performance, using multiple disjoint controllers coupled with the two-phase property, while maintaining the simplicity of centralized schemes. The detection step is divided into two phases. Phase 1 analyzes the conditions of the system of interacting transactions, involving phase 2 only if conditions are possible for deadlocks to occur. Phase 2 performs the actual cycle detection. The proposed algorithm can be used in transaction-based distributed processing systems. Some results on the complexity of the algorithm are given