A mutable protocol for consensus in large groups

In this paper we propose the mutable con- sensus protocol, a pragmatic and theoretically appealing approach to enhance the performance of distributed con- sensus with a large number of participants. First, an apparently inefficient consensus protocol is developed using the very simple stubborn channel abstraction for unreliable message passing. Then, the introduction of judiciously chosen finite delays in the implementation of channels makes it likely that the transmission of some messages is avoided. Although this does not affect correctness, which rests on an asynchronous system model, the message exchange pattern at the network level changes noticeably and can be made to resemble several different protocols. A particularly appealing instantiation, called the permutation gossip, allows the protocol to scale gracefully to a large number of processes