[jira] [Commented] (KAFKA-9839) IllegalStateException on metadata update when broker learns about its new epoch after the controller

["Jun Rao (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-9839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17079544#comment-17079544 ] 

Jun Rao commented on KAFKA-9839:
--------------------------------

Thanks for reporting this, Anna. Accepting UPDATE_METADATA (and other similar requests from the controller) with a larger broker epoch is probably the easier solution.

> IllegalStateException on metadata update when broker learns about its new epoch after the controller
> ----------------------------------------------------------------------------------------------------
>
>                 Key: KAFKA-9839
>                 URL: https://issues.apache.org/jira/browse/KAFKA-9839
>             Project: Kafka
>          Issue Type: Bug
>          Components: controller, core
>    Affects Versions: 2.3.1
>            Reporter: Anna Povzner
>            Priority: Critical
>
> Broker throws "java.lang.IllegalStateException: Epoch XXX larger than current broker epoch YYY"  on UPDATE_METADATA when the controller learns about the broker epoch and sends UPDATE_METADATA before KafkaZkCLient.registerBroker completes (the broker learns about its new epoch).
> Here is the scenario we observed in more detail:
> 1. ZK session expires on broker 1
> 2. Broker 1 establishes new session to ZK and creates znode
> 3. Controller learns about broker 1 and assigns epoch
> 4. Broker 1 receives UPDATE_METADATA from controller, but it does not know about its new epoch yet, so we get an exception:
> ERROR [KafkaApi-3] Error when handling request: clientId=1, correlationId=0, api=UPDATE_METADATA, body={
> .........
> java.lang.IllegalStateException: Epoch XXX larger than current broker epoch YYY at kafka.server.KafkaApis.isBrokerEpochStale(KafkaApis.scala:2725) at kafka.server.KafkaApis.handleUpdateMetadataRequest(KafkaApis.scala:320) at kafka.server.KafkaApis.handle(KafkaApis.scala:139) at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:69) at java.lang.Thread.run(Thread.java:748)
> 5. KafkaZkCLient.registerBroker completes on broker 1: "INFO Stat of the created znode at /brokers/ids/1"
> The result is the broker has a stale metadata for some time.
> Possible solutions:
> 1. Broker returns a more specific error and controller retries UPDATE_MEDATA
> 2. Broker accepts UPDATE_METADATA with larger broker epoch.



--
This message was sent by Atlassian Jira
(v8.3.4#803005)