Chandra–Toueg consensus algorithm: Difference between revisions

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{{inline|date=May 2024}}

The '''Chandra–Toueg consensus algorithm''', published by Tushar Deepak Chandra and Sam Toueg in 1996, is an algorithm for solving [[Consensus (computer science)|consensus]] in a network of unreliable processes equipped with an ''eventually strong'' [[failure detector]]. The failure detector is an abstract version of [[Timeout (computing)|timeouts]]; it signals to each process when other processes may have crashed. An eventually strong failure detector is one that never identifies ''some'' specific non-faulty process as having failed after some initial period of confusion, and, at the same time, eventually identifies ''all'' faulty processes as failed (where a faulty process is a process which eventually fails or crashes and a non-faulty process never fails). The Chandra–Toueg consensus algorithm assumes that the number of faulty processes, denoted by {{var|f}}, is less than n/2 (i.e. the minority), i.e. it assumes {{var|f}} < {{var|n}}/2, where n is the total number of processes.

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# The coordinator waits to receive ack(r) or nack(r) from a majority of processes.

## If it receives ack(r) from a majority, it sends decide(preference) to all processes.

# Any process that receives decide(preference) for the first time sendsrelays decide(preference) to all processes, then decides preference and terminates.

Note that this algorithm is used to decide only on one value.

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{{DEFAULTSORT:Chandra-Toueg consensus algorithm}}

[[Category:Distributed algorithms]]

[[Category:Fault tolerance]]

[[Category:Fault-tolerant computer systems]]