Synchronization with Eventcounts and Sequencers Synchronization of concurrent processes requires controlling the relative ordering of events in the processes. A new synchronization mechanism is proposed, using abstract objects called eventcounts and sequencers, that allows processes to control the ordering of events directly, rather than using mutual exclusion to protect manipulations of shared variables that control ordering of events. Direct control of ordering seems to simplify correctness arguments and also simplifies implementation in distributed systems. The mechanism is defined formally, and then several examples of its use are given. The relationship of the mechanism to protection mechanisms in the system is explained; in particular, eventcounts are shown to be applicable to situations where confinement of information matters. An implementation of eventcount s and sequencers in a system with shared memory is described. CACM February, 1979 Reed, D. Kanodia, R. Process synchronization, interprocess communication, distributed systems, security models, mutual exclusion, semaphores 4.30 4.32 CA790207 DH April 12, 1979 10:03 AM 2320 4 3128 2597 4 3128 2700 4 3128 2777 4 3128 2840 4 3128 2851 4 3128 2865 4 3128 2866 4 3128 2869 4 3128 2895 4 3128 2898 4 3128 2912 4 3128 2938 4 3128 2945 4 3128 2946 4 3128 2946 4 3128 2972 4 3128 3043 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3128 4 3128 3144 4 3128 3148 4 3128 3158 4 3128 2150 5 3128 2376 5 3128 2436 5 3128 2597 5 3128 2865 5 3128 2866 5 3128 2870 5 3128 2912 5 3128 3082 5 3128 3128 5 3128 3128 5 3128 3128 5 3128