An Impossibility Result on Strong Linearizability in Message-Passing Systems (2108.01651v2)

Abstract: We prove that in asynchronous message-passing systems where at most one process may crash, there is no lock-free strongly linearizable implementation of a weak object that we call Test-or-Set (ToS). This object allows a single distinguished process to apply the set operation once, and a different distinguished process to apply the test operation also once. Since this weak object can be directly implemented by a single-writer single-reader (SWSR) register (and other common objects such as max-register, snapshot and counter), this result implies that there is no $1$-resilient lock-free strongly linearizable implementation of a SWSR register (and of these other objects) in message-passing systems. We also prove that there is no $1$-resilient lock-free \emph{write} strongly-linearizable implementation of a 2-writer 1-reader (2W1R) register in asynchronous message-passing systems.