Apache Kafka 面试题与答案

问题 11. Explain the concept of Leader and Follower.

In every partition of Kafka, there is one server which acts as the Leader, and none or more servers plays the role as a Followers.

问题 12. What ensures load balancing of the server in Kafka?

As the main role of the Leader is to perform the task of all read and write requests for the partition, whereas Followers passively replicate the leader. Hence, at the time of Leader failing, one of the Followers takeover the role of the Leader. Basically, this entire process ensures load balancing of the servers.

问题 13. What roles do Replicas and the ISR play?

• Basically, a list of nodes that replicate the log is Replicas. Especially, for a particular partition. However, they are irrespective of whether they play the role of the Leader.
• In addition, ISR refers to In-Sync Replicas. On defining ISR, it is a set of message replicas that are synced to the leaders.

问题 14. Why are Replications critical in Kafka?

Because of Replication, we can be sure that published messages are not lost and can be consumed in the event of any machine error, program error or frequent software upgrades.

问题 15. If a Replica stays out of the ISR for a long time, what does it signify?

Simply, it implies that the Follower cannot fetch data as fast as data accumulated by the Leader.