[jira] [Resolved] (KAFKA-6214) Using standby replicas with an in memory state store causes Streams to crash

["Guozhang Wang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-6214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Guozhang Wang resolved KAFKA-6214.
----------------------------------
       Resolution: Fixed
    Fix Version/s: 1.0.1
                   1.1.0

Issue resolved by pull request 4239
[https://github.com/apache/kafka/pull/4239]

> Using standby replicas with an in memory state store causes Streams to crash
> ----------------------------------------------------------------------------
>
>                 Key: KAFKA-6214
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6214
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 0.11.0.1
>            Reporter: Matt Farmer
>            Assignee: Damian Guy
>              Labels: statestore
>             Fix For: 1.1.0, 1.0.1
>
>
> We decided to start experimenting with Standby Replicas of our State Stores by setting the following configuration setting:
> {code}
> num.standby.replicas=1
> {code}
> Most applications did okay with this except for one that used an in memory state store instead of a persistent state store. With the new configuration, the first instance of this application booted fine. When the second instance came up, both instances crashed with the following exception:
> {code}
> java.lang.IllegalStateException: Consumer is not subscribed to any topics or assigned any partitions
>         at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1037)
>         at org.apache.kafka.streams.processor.internals.StreamThread.maybeUpdateStandbyTasks(StreamThread.java:752)
>         at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:524)
>         at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:480)
>         at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:457)
> {code}
> Monit attempted to restart both instances but they would just continue to crash over and over again. The state store in our problematic application is declared like so:
> {code}
> Stores
>     .create("TheStateStore")
>     .withStringKeys()
>     .withStringValues()
>     .inMemory()
>     .build()
> {code}
> Luckily we had a config switch in place that could turn on an alternate, persistent state store. As soon as we flipped to the persistent state store, things started working as we expected.



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