[jira] [Created] (KAFKA-16144) Controller leader checkQuorum timer should skip only 1 controller case

["Luke Chen (Jira)" <ji...@apache.org>]

Luke Chen created KAFKA-16144:
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             Summary: Controller leader checkQuorum timer should skip only 1 controller case
                 Key: KAFKA-16144
                 URL: https://issues.apache.org/jira/browse/KAFKA-16144
             Project: Kafka
          Issue Type: Bug
            Reporter: Luke Chen


In KAFKA-15489, we fixed the potential "split brain" issue by adding the check quorum timer. This timer will be updated when the follower fetch request arrived. And it expires the timer when the there are no majority of voter followers fetch from leader, and resign the leadership. 

But in KAFKA-15489, we forgot to consider the case where there's only 1 controller node. If there's only 1 controller node (and no broker node), there will be no fetch request arrived, so the timer will expire each time. However, if there's only 1 node, we don't have to care about the "check quorum" at all. We should skip the check for only 1 controller node case.

Currently, this issue will happen only when there's 1 controller node and no any broker node (i.e. no fetch request sent to the controller). 



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