What is the mechanism of the Zookeeper cluster leader e…

The mechanism for electing a leader in a Zookeeper cluster is implemented through the ZAB protocol (Zookeeper Atomic Broadcast). When the leader node in the Zookeeper cluster fails or is unable to communicate due to network partition, Zookeeper will automatically trigger an election process to select a new leader node.

The election process includes the following steps:

1. Choose one node in the cluster to act as the Leader Election Coordinator across all nodes.
2. The leader election coordinator initiates a vote request to all nodes in the cluster and waits for their responses.
3. When a node receives a vote request, it checks its own status. If the current node has not voted or the received vote request has a higher Zookeeper Transaction ID (ZXID), it will send its vote information to the Leader election coordinator.
4. The leader election coordinator will wait for a certain period of time before tallying the collected voting information.
5. If a node receives votes from the majority of nodes and has the highest ZXID among them, it will become the new Leader node.
6. After receiving the election result of the new Leader node, the other nodes will update their own status and, if necessary, reconnect to the new Leader node.

The election mechanism of Zookeeper ensures that only one Leader node exists in the cluster, guaranteeing consistency and reliability of the data.