Open source Java implementation for Raft consensus protocol.

Clone this repo:
  1. 03f3b68 RATIS-1388 Add an isEmpty method to TaskQueue. (#487) by Tsz-Wo Nicholas Sze · 2 weeks ago master
  2. 3f4f5ff RATIS-1384.Change pending request limit unit to MB (#483) by Sadanand Shenoy · 3 weeks ago
  3. 9b57296 RATIS-1386. Some MetricsRegistry instances never unregistered (#486) by Doroszlai, Attila · 5 weeks ago
  4. 4bef7f8 RATIS-1387. bump to fix 0.7.0 thirdparty (#485) by Elek, Márton · 6 weeks ago
  5. a606fd2 RATIS-1385. Project assembly fails on linux (#484) by Elek, Márton · 6 weeks ago

Apache Ratis

Apache Ratis is a Java library that implements the Raft protocol [1], where an extended version of the Raft paper is available at The paper introduces Raft and states its motivations in following words:

Raft is a consensus algorithm for managing a replicated log. It produces a result equivalent to (multi-)Paxos, and it is as efficient as Paxos, but its structure is different from Paxos; this makes Raft more understandable than Paxos and also provides a better foundation for building practical systems.

Ratis aims to make Raft available as a java library that can be used by any system that needs to use a replicated log. It provides pluggability for state machine implementations to manage replicated states. It also provides pluggability for Raft log, and rpc implementations to make it easy for integration with other projects. Another important goal is to support high throughput data ingest so that it can be used for more general data replication use cases.


  1. Diego Ongaro and John Ousterhout, In Search of an Understandable Consensus Algorithm, 2014 USENIX Annual Technical Conference (USENIX ATC 14) (Philadelphia, PA), USENIX Association, 2014, pp. 305-319.