A distributed deadlock detection and resolution algorithm based on a hybrid wait-for graph and probe generation scheme

We present a continuous deadlock detection and resolution algorithm in distributed database systems. Our algorithm maintains an augmented transaction wait-for graph at each site and uses a modified priority-based probe generation scheme in order to detect local deadlocks without transmitting any intra-site deadlock detection messages, to minimize the number of inter-site messages sent for detection of global deadlocks and also for the early detection of global deadlocks that might occur in the future without transmitting detection messages repeatedly. The augmented transaction wait-for graph contains, in addition to lock-wait information, information about message-wait relationships among agents of a transaction, probes received from other sites and transitive wait-for relationships among transactions. Global deadlocks are declared whenever a transitive wait-for relationship from an agent of a global transaction is constructed for some agent of the transaction.