Atomic Broadcast Algorithms Research Articles

Ring Paxos: High-Throughput Atomic Broadcast†

Atomic broadcast is an important communication primitive often used to implement state-machine replication. Despite the large number of atomic broadcast algorithms proposed in the literature, few papers have discussed how to turn these algorithms into efficient executable protocols. This paper focuses on a class of atomic broadcast algorithms based on Paxos, with its corresponding desirable properties: safety under asynchrony assumptions, liveness under weak synchrony assumptions, and resiliency-optimality. The paper presents two protocols, M-Ring Paxos and U-Ring Paxos, derived from Paxos. The protocols inherit the properties of Paxos and can be implemented very efficiently. We report a detailed performance analysis of M-Ring Paxos and U-Ring Paxos and compare them to other atomic broadcast protocols.

A Fault-Tolerant Token-Based Atomic Broadcast Algorithm

Many atomic broadcast algorithms have been published in the last 20 years. Token-based algorithms represent a large class of these algorithms. Interestingly, all the token-based atomic broadcast algorithms rely on a group membership service and none of them uses unreliable failure detectors directly. This paper presents the first token-based atomic broadcast algorithm that uses an unreliable failure detector instead of a group membership service. It requires a system size that is quadratic in the number of supported failures. The special case of a single supported failure (f=1) requires n=3 processes. We experimentally evaluate the performance of this algorithm in local and wide area networks, in order to emphasize that atomic broadcast is efficiently implemented by combining a failure detector and a token-based mechanism. The evaluation shows that the new token-based algorithm surpasses the performance of the other algorithms in most small-system settings.

EFFICIENT SOLUTION TO UNIFORM ATOMIC BROADCAST

Chandra and Toueg proposed in 1993 a new approach to overcome the impossibility of reaching deterministically Consensus — and by corollary Atomic Broadcast — in asynchronous systems subject to crash failures. They augment the asynchronous system with a possibly Unreliable Failure Detector which provides some information about the operational state of processes. In this paper, we present an extension of the Consensus problem that we call Uniform Prefix Agreement. This extension enables all the processes to propose a flow of messages during an execution — instead of one as in the Consensus problem — and uses all these proposed messages to compose the decision value. Prefix Agreement is based on an Unreliable Failure Detector. We use repeated executions of Prefix Agreement to build an efficient Uniform Atomic Broadcast algorithm. This paper describes the Uniform Prefix Agreement and Uniform Atomic Broadcast algorithms, and provides proofs of their correctness.