Efficient and Robust Sharing of Memory in Message-Passing Systems

A simulation of a wait-free, atomic, single-writer multireader register in an asynchronous message passing system is presented. The simulation can withstand the failure of up to half of the processors and requires O(n) messages (for each read or write operation), assuming there are n+1 processors in the system. It improves on the previous simulation, which requires O(n2) messages (for each read or write operation). The message complexity of the new simulation is within a constant factor of the optimum. The new simulation improves the complexity of algorithms for the following problems in the message-passing model in the presence of processor failures: multiwriter multireader registers, concurrent time-stamp systems, ?-exclusion, atomic snapshots, randomized consensus, implementation of data structures, as well as improved fault-tolerant algorithms for any solvable decision task.