Leader election − Electing a node as leader for coordination purposes. It is similar to DNS, but for nodes.Ĭonfiguration management − Latest and up-to-date configuration information of the system for a joining node.Ĭluster management − Joining/leaving of a node in a cluster and node status in real time. Naming service − Identifying the nodes in a cluster by name. Timeliness - The client's view of the system is guaranteed to be up-to-date within a certain time bound. Reliability - Once an update has been applied, it will persist from that time forward until a client overwrites the update. Single System Image - A client will see the same view of the service regardless of the server that it connects to. Sequential Consistency - Updates from a client will be applied in the order that they were sent.Ītomicity - Updates either succeed or fail.

As long as a majority of the servers are available, the Zookeeper service will be available. They maintain an in-memory image of state, along with transaction logs and snapshots in a persistent store. The servers that make up the ZooKeeper service must all know about each other. Zookeeper applications run on thousands of machines, and it performs best where reads are more common than writes, at ratios of around 10:1. It is especially fast in 'read-dominant' workloads. High throughput and low latency - data is stored data in memory and on disk as well.Īutomatic failover: When a Zookeeper dies, the session is automatically migrated over to another Zookeeper. High performant - The performance aspects of Zookeeper means it can be used in large, distributed systems. Reliability - The reliability aspects keep it from being a single point of failure.Ītomicity − Data transfer either succeeds or fails completely, but no transaction is partial. Ordered Messages - The strict ordering means that sophisticated synchronization primitives can be implemented at the client. Synchronization − Mutual exclusion and co-operation between server processes. A few of the distributed applications that use Zookeeper are Apache Hadoop, Apache Kafka, and Apache Storm. ZooKeeper is a coordination service for distributed applications with the motto 'ZooKeeper: Because Coordinating Distributed Systems is a Zoo.' The ZooKeeper framework was originally built at Yahoo.

Zookeeper heartbeat timeout synctime