Advertisement

On the limitation of the global time assumption in distributed systems

  • Uri Abraham
  • Shai Ben-David
  • Shlomo Moran
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 579)

Abstract

An ongoing debate among theoreticians of distributed systems concerns the global time issue. The basic question seems to be to what extent does a model with global time reflect the ‘real’ behavior of a distributed system. The assumption of the existence of global time simplifies the analysis of distributed algorithms to an extent that makes it almost irresistible. On the other hand it should be clear that when the operations discussed are of time duration that is comparable to that of the time needed for a signal to pass between different components of the system, then such an assumption is unrealistic. The debate is of a somewhat philosophical nature mainly because, so far, there were no known examples of faulty conclusions caused by excessive use of the global time model.

In this note we demonstrate, for the first time, a protocol that is guaranteed to perform well as long as it is run in a system that enjoys the existence of global time, yet it may fail in some other conceivable circumstances. The protocol is very simple and is often used as a basic step in protocols for mutual exclusion.

By the results of [5], such a phenomenon could not have occurred had we been running our protocol on one of the three common types of shared registers (safe, regular or atomic). Another contribution of this work is the introduction of a new class of shared memory registers — ‘weakly regular registers’. Our weak regularity is a natural variant on Lamport's definition of regularity of registers.

Keywords

Shared Memory Read Operation Global Time System Execution Philosophical Nature 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    Abraham, U., “On interprocess communication and the problem of common atomic registers”, manuscript, 1989.Google Scholar
  2. [2]
    Abraham, U., and Ben-David, S., “Informal and Formal Correctness Proofs for Programs”, manuscript, November 1987.Google Scholar
  3. [3]
    Avraham, U., Ben-David, S., and Magidor, M., “On Global Time and Inter-Process Communication”, Semantics for Concurrency, M.Z. Kwiatkowska, M.W. Shield, and R.M. Thomas (Eds.), Springer-Verlag, July 1990, 311–323.Google Scholar
  4. [4]
    Anger, F. D., “On Lamport's interprocess communication model”, ACM Transactions on Programming Languages and Systems, Vol. 11 No. 3, July 1989, 404–417.Google Scholar
  5. [5]
    Ben-David, S., “The global-time assumption and semantics for concurrent systems”, Proceedings of the 7th Annual ACM Symposium on Principles of Distributed Computing, ACM Press, 1988, 223–232.Google Scholar
  6. [6]
    Ben-David, S., “On Lamport's Shared Memory Registers”, in preparation.Google Scholar
  7. [7]
    Van Benthem, J. F. A. K., “ Time, Logic and computation”, in Bakker, Roever and Rozenberg (Eds), Linear Time, Branching Time and partial Order in Logics and Models for Concurrency, pp. 1–49, Springer, Berlin, 1989.Google Scholar
  8. [8]
    Fishburn, P.C., “Interval orders and interval graphs”, Wiley, New-York (Wiley-Interscience series in discrete mathematics), 1987.Google Scholar
  9. [9]
    Lamport, L., “The mutual Exclusion Problem: Part I-A Theory of interprocess Communication; Part II-Statements and Solutions”, J. of the A.C.M., Vol 33, 21986), pp. 313–326.Google Scholar
  10. [10]
    Lamport, L., “On Interprocess Communication, Part I: Basic formalism, Part II: Algorithms”, Distributed Computing, Vol. 1(1986), pp. 77–101.Google Scholar
  11. [11]
    Wiener, N., “A contribution to the theory of relative position”, Proc. Camb. Philos. Soc. 17(1914), pp.441–449.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • Uri Abraham
    • 1
  • Shai Ben-David
    • 2
  • Shlomo Moran
    • 2
  1. 1.Dept. of Mathematics and Computer ScienceBen-Gurion UniversityBeer-ShevaIsrael
  2. 2.Dept. of Computer ScienceTechnionHaifaIsrael

Personalised recommendations