One for All and All for One: Scalable Consensus in a Hybrid Communication Model

Michel Raynal, Jiannong Cao
2019 2019 IEEE 39th International Conference on Distributed Computing Systems (ICDCS)  
This paper addresses consensus in an asynchronous model where the processes are partitioned into clusters. Inside each cluster, processes can communicate through a shared memory, which favors efficiency. Moreover, any pair of processes can also communicate through a messagepassing communication system, which favors scalability. In such a "hybrid communication" context, the paper presents two simple binary consensus algorithms (one based on local coins, the other one based on a common coin).
more » ... a common coin). These algorithms are straightforward extensions of existing message-passing randomized round-based consensus algorithms. At each round, the processes of each cluster first agree on the same value (using an underlying shared memory consensus algorithm), and then use a message-passing algorithm to converge on the same decided value. The algorithms are such that, if all except one processes of a cluster crash, the surviving process acts as if all the processes of its cluster were alive (hence the motto "one for all and all for one"). As a consequence, the hybrid communication model allows us to obtain simple, efficient, and scalable fault-tolerant consensus algorithms. As an important side effect, according to the size of each cluster, consensus can be obtained even if a majority of processes crash.
doi:10.1109/icdcs.2019.00053 dblp:conf/icdcs/RaynalC19 fatcat:kmyd2p6bzzetvjung66tlfn27q