Fast Collect in the absence of contention

Abstract

We present a generic module, called Fast Collect. Fast Collect is an implementation of single-writer multi-reader (SWMR) shared-memory in an asynchronous system in which a processor updates its cell and then reads in any order all the other cells. Our simple implementation of Fast Collect uses some multiwriter multi-reader (MWMR) variables and one local Boolean per processor, such that eventually, in the absence of contention, i.e. if only a single processor repeatedly performs collect, the amortized cost per each collect is a constant. With the example of Disk Paxos we show how Fast Collect can be used as a building block in wait-free algorithms.