The SprayList: a scalable relaxed priority queue

High-performance concurrent priority queues are essential for applications such as task scheduling and discrete event simulation. Unfortunately, even the best performing implementations do not scale past a number of threads in the single digits. This is because of the sequential bottleneck in accessing the elements at the head of the queue in order to perform a DeleteMin operation. In this paper, we present the SprayList, a scalable priority queue with relaxed ordering semantics. Starting from a nonblocking SkipList, the main innovation behind our design is that the DeleteMin operations avoid a sequential bottleneck by “spraying” themselves onto the head of the SkipList list in a coordinated fashion. The spraying is implemented using a carefully designed random walk, so that DeleteMin returns an element among the first O(p log3 p) in the list, with high probability, where p is the number of threads. We prove that the running time of a DeleteMin operation is O(log3 p), with high p...

• Type: Journal
• Year: 2015
• Where: PPOPP
• Authors: Dan Alistarh, Justin Kopinsky, Jerry Li, Nir Shavit
• Keywords: Distributed And Parallel Computing, PPOPP 2015