Weak Read/Write Registers

Abstract

In [2], Lamport has defined three classes of shared registers which support read and write operations, called —safe, regular and atomic—depending on their properties when several reads and/or writes are executed concurrently. We consider generalizations of Lamport’s notions, called k-safe, k-regular and k-atomic. First, we provide constructions for implementing 1-atomic registers (the strongest type) in terms of k-safe registers (the weakest type). Then, we demonstrate how the constructions enable to easily and efficiently solve classical synchronization problems, such as mutual exclusion and ℓ-exclusion, using single-writer multi-reader k-safe bits, for any k ≥ 1. We also explain how, by using k-registers, it is possible to provide some level of resiliency against memory reordering.