Shulou(Shulou.com)06/03 Report--

In this issue, the editor will bring you about what is ZooKeeper. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

ZooKeeper is an open source distributed coordinator and a typical distributed data consistency solution. It is designed to encapsulate complex and error-prone distributed consistency services to form an efficient and reliable system and provide users with a series of easy-to-use atomic operations.

Main characteristics of ZooKeeper

Zookeeper itself is a distributed program, as long as more than half of the nodes survive, zookeeper can serve normally.

To ensure high availability, zookeeper is usually deployed in the form of a cluster, so that zookeeper itself is available as long as most of the machines in the cluster are available.

Zookeeper keeps data in memory, which ensures high throughput and low latency

Zookeeper is high performance, especially in programs that read more than write, because writing causes state to be synchronized across all servers.

Zookeeper has the concept of temporary nodes. When the client session that creates the temporary node remains active, the temporary node always exists. When the session ends, the temporary node is deleted.

The bottom layer of zookeeper provides only two functions. 1 manages the data submitted by the user program, and 2 provides monitoring services for the data nodes submitted by the user program.

Characteristics of ZooKeeper

ZooKeeper is based on Fast Paxos algorithm, Paxos algorithm has the problem of live lock, that is, when there are multiple proposer staggered submissions, it is possible that no proposer can be submitted successfully due to mutual exclusion, while Fast Paxos has made some optimizations to produce a leader (leader) through election, and only leader can submit proposer. The specific algorithm can be seen in Fast Paxos. Therefore, if you want to understand ZooKeeper, you must first know something about Fast Paxos. [2]

The basic operation flow of ZooKeeper:

1. Elect Leader.

2. Synchronize data.

3. There are many algorithms in the process of electing Leader, but the election criteria are the same.

4. Leader should have the highest execution ID, similar to root permission.

5. Most of the machines in the cluster respond and accept the selected Leader.

The above is the editor for you to share what is ZooKeeper, if you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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