Reaching Consensus in the Presence of Contention-Related Crash Failures

Anaïs Durand, Michel Raynal, Gadi Taubenfeld

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


While consensus is at the heart of many coordination problems in asynchronous distributed systems prone to process crashes, it has been shown to be impossible to solve in such systems where processes communicate by message-passing or by reading and writing a shared memory. Hence, these systems must be enriched with additional computational power for consensus to be solved on top of them. This article presents a new restriction of the classical basic computational model that combines process participation and a constraint on failure occurrences that can happen only while a predefined contention threshold has not yet been bypassed. This type of failure is called λ -constrained crashes, where λ defines the considered contention threshold. It appears that when assuming such contention-related crash failures and enriching the system with objects whose consensus number is k≥ 1, consensus for n processes can be solved for any n≥ k assuming up to k failures. The article proceeds incrementally. It first presents an algorithm that solves consensus on top of read/write registers if at most one crash occurs before the contention threshold λ= n- 1 has been bypassed. Then, it shows that if the system is enriched with objects whose consensus number is k≥ 1, then when λ= n- k, consensus can be solved despite up to kλ -constrained crashes, for any n≥ k, andwhen λ= n- 2 k+ 1, consensus can be solved despite up to 2 k- 1 λ -constrained crashes, assuming k divides n. Finally, impossibility results are presented for the number of λ -constrained failures that can be tolerated.

Original languageEnglish
Title of host publicationStabilization, Safety, and Security of Distributed Systems - 24th International Symposium, SSS 2022, Proceedings
EditorsStéphane Devismes, Franck Petit, Karine Altisen, Giuseppe Antonio Di Luna, Antonio Fernandez Anta
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages13
ISBN (Print)9783031210167
StatePublished - 2022
Externally publishedYes
Event24th International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2022 - Clermont-Ferrand, France
Duration: 15 Nov 202217 Nov 2022

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume13751 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference24th International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2022

Bibliographical note

Publisher Copyright:
© 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.


  • Asynchronous system
  • Atomic register
  • Concurrency
  • Consensus algorithm
  • Consensus number
  • Contention
  • Participating process
  • Process crash failure
  • Read/write register
  • λ -constrained failure


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