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Ramnatthan Alagappan commented on KAFKA-1120: --------------------------------------------- I ran into this issue and have a reproducible setup irrespective of the number of partitions or nodes. [~onurkaraman]'s analysis in comment @ [#comment-16113645] is correct. The root cause is that the shutdown broker restarts and registers with ZK in a short interval of time. During this time, ZK delivers a callback for deletion of the broker. Before ZKClient can reestablish the callback (by issuing a stat call), the broker registers with ZK. By the time ZKClient gets the /brokers/ids node from ZK, the shutdown broker also appears in /brokers/ids. With this, the shutdown broker appears both in curBrokerIds and liveOrShuttingDownBrokerIds, causing newBrokerIds to be empty, which causes this problem. > Controller could miss a broker state change > -------------------------------------------- > > Key: KAFKA-1120 > URL: https://issues.apache.org/jira/browse/KAFKA-1120 > Project: Kafka > Issue Type: Sub-task > Components: core > Affects Versions: 0.8.1 > Reporter: Jun Rao > Assignee: Mickael Maison > Labels: reliability > Fix For: 1.1.0 > > > When the controller is in the middle of processing a task (e.g., preferred > leader election, broker change), it holds a controller lock. During this > time, a broker could have de-registered and re-registered itself in ZK. After > the controller finishes processing the current task, it will start processing > the logic in the broker change listener. However, it will see no broker > change and therefore won't do anything to the restarted broker. This broker > will be in a weird state since the controller doesn't inform it to become the > leader of any partition. Yet, the cached metadata in other brokers could > still list that broker as the leader for some partitions. Client requests > routed to that broker will then get a TopicOrPartitionNotExistException. This > broker will continue to be in this bad state until it's restarted again. -- This message was sent by Atlassian JIRA (v6.4.14#64029)