Optimal Deadlock Detection in Distributed Systems Based on Locally Constructed Wait-for Graphs - Distributed Computing Systems, 1996., Proceedings of the 16th International Conference on

We present a new algorithm for detecting generalized deadlocks in distributed systems. Our algorithm incrementally constructs and reduces a wait-for graph (WFG) at an initiator process. This WFG is then searched for deadlock. The proposed algorithm has two primary advantages: First, it avoids sending messages along the edges of the global wait-for graph (WFG), thereby achieving a worst-case message complexity of 2n, where n is the number of processes in the WFG. Since information must be obtained from every process reachable from the initiatol; this is optimal to within a constant factol: All the existing algorithms for the same problem construct a distributed snapshot of the WFG. As this involves sending messages along the edges of the WFG, the best available message complexity among these algorithms is 4e 2n + 21, which is O ( n 2 ) in the worst case, where e and 1 are the number of edges and leaves in the WFG, respectively. Second, since the information about a detected deadlock is readily available at the initiatorprocess, rather lhan distributed among dizerent processes, it significantly !rimplifies the task of deadlock resolution, and helps to reduce system overhead associated with the resolution. The time complexity of our algorithm is also better than or equal to the existing algorithms.