Apache Ratis (Incubating)

Clone this repo:
  1. 90cd474 RATIS-795. Read SateMachine data failure should result in log fail notification. Contributed by Siddharth Wagle. by Shashikant Banerjee · 2 days ago master
  2. e51d531 RATIS-796. Add watch time out for Ratis Client. Contributed by Bharat Viswanadham. by Shashikant Banerjee · 2 days ago
  3. 9954074 RATIS-458. GrpcLogAppender#shouldWait should wait on pending log entries to follower. Contributed by Lokesh Jain. by Lokesh Jain · 2 weeks ago
  4. fd7091c Statemachine updater fails with assertion. by Shashikant Banerjee · 2 weeks ago
  5. 92dac6e RATIS-781. Add ResourceSemaphore#acquire(int... permits) api. Contributed by Lokesh Jain. by Lokesh Jain · 2 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 https://raft.github.io/raft.pdf. 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.