Fast Dual Ring Queues

Abstract

In this paper, we present two new FIFO dual queues. Like all dual queues, they arrange for dequeue operations to block when the queue is empty, and to complete in the original order when data becomes available. Compared to alternatives in which dequeues on an empty queue return an error code and force the caller to retry, dual queues provide a valuable guarantee of fairness. Our algorithms, based on Morrison and Afek's LCRQ from PPoPP'13, outperform existing dual queues - notably the one in java.util.concurrent - by a factor of four to six. For both of our algorithms, we present extensions that guarantee lock freedom, albeit at some cost in performance