Virtual precedence in asynchronous systems: Concept and applications

Abstract

This paper introduces the Virtual Precedence (VP) property. An interval-based abstraction of a computation satisfies the VP property if it is possible to timestamp its intervals in a consistent way (i.e., time does not decrease inside a process and increases after communication). A very general protocol Ƥ that builds abstractions satisfying the VP property is proposed. It is shown that the VP property encompasses logical clocks systems and communication-induced checkpointing protocols. A new and efficient protocol which ensures no local checkpoint is useless is derived from Ƥ. This protocol compares very favorably with existing protocols that solve the same problem. This shows that, due the generality of its approach, a theory (namely, here VP) can give efficient solutions to practical problems (here the prevention of useless checkpoints).