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Sönke Liebau commented on KAFKA-8359: ------------------------------------- I dug around a little as to where this default comes from, but the only thing that I could find is [this brief conversation|https://reviews.apache.org/r/15711/#comment56318]. Personally I think between the ability to customize this parameter, monitoring PreferredReplicaImbalanceCount and manually triggering a leader rebalance there is no real need to change the default behavior, but I am very happy to be convinced otherwise. Would it as an alternative be useful to make this parameter dynamically updateable without cluster restart? > Reconsider default for leader imbalance percentage > -------------------------------------------------- > > Key: KAFKA-8359 > URL: https://issues.apache.org/jira/browse/KAFKA-8359 > Project: Kafka > Issue Type: Improvement > Reporter: Dhruvil Shah > Priority: Major > > By default, the leader imbalance ratio is 10%. This means that the controller > won't trigger preferred leader election for a broker unless the ratio of the > number of partitions a broker is the current leader of and the number of > partitions it is the preferred leader of is off by more than 10%. The problem > is when a broker is catching up after a restart, the smallest topics tend to > catch up first and the largest ones later, so the 10% remaining difference > may not be proportional to the broker's load. To keep better balance in the > cluster, we should consider setting > `leader.imbalance.per.broker.percentage=0` by default so that the preferred > leaders are always elected. -- This message was sent by Atlassian JIRA (v7.6.3#76005)