Towards a Necessary and Sufficient Condition for Wait-free Synchronization (Extended Abstract)

) James H. Anderson and Mark Moir Department of Computer Science, The University of Maryland College Park, Maryland 20742-3255 U.S.A. Abstract. We define a class of shared objects called snapshot objects, and give a necessary and sufficient condition for the existence of a waitfree implementation of such objects from atomic registers. Snapshot objects can be accessed by means of a read operation that returns the entire object state, or by a set of operations that do not return values. Our condition for the existence of a wait-free implementation requires that for any pair of operation invocations, either the two invocations commute or one overwrites the other. 1 Introduction The resilient implementation of shared objects is a subject that has received much recent attention. A shared object is a data structure that is accessed by a collection of processes by means of a fixed set of operations. An implementation of a shared object is k-resilient iff any process can complete any opera..

Notes on Theory of Distributed Systems

Notes for the Yale course CPSC 465/565 Theory of Distributed Systems