Distributed Computing

, Volume 12, Issue 4, pp 179–195

Plausible clocks: constant size logical clocks for distributed systems

  • Francisco J. Torres-Rojas
  • Mustaque Ahamad
Original articles

DOI: 10.1007/s004460050065

Cite this article as:
Torres-Rojas, F. & Ahamad, M. Distrib Comput (1999) 12: 179. doi:10.1007/s004460050065


In a Distributed System with N sites, the precise detection of causal relationships between events can only be done with vector clocks of size N. This gives rise to scalability and efficiency problems for logical clocks that can be used to order events accurately. In this paper we propose a class of logical clocks called plausible clocks that can be implemented with a number of components not affected by the size of the system and yet they provide good ordering accuracy. We develop rules to combine plausible clocks to produce more accurate clocks. Several examples of plausible clocks and their combination are presented. Using a simulation model, we evaluate the performance of these clocks. We also present examples of applications where constant size clocks can be used.

Key words:Logical clocks – Causality detection – Distributed algorithms 

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Francisco J. Torres-Rojas
    • 1
  • Mustaque Ahamad
    • 1
  1. 1.College of Computing, Georgia Institute of Technology, USA (e-mail: {torres, mustaq}@cc.gatech.edu) US

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