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https://issues.apache.org/jira/browse/KAFKA-7657?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thomas Crowley updated KAFKA-7657:
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    Summary: Invalid reporting of stream state in Kafka streams application  
(was: Invalid reporting of StreamState in KafkaStreams application)

> Invalid reporting of stream state in Kafka streams application
> --------------------------------------------------------------
>
>                 Key: KAFKA-7657
>                 URL: https://issues.apache.org/jira/browse/KAFKA-7657
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 2.0.1
>            Reporter: Thomas Crowley
>            Priority: Minor
>
> We have a streams application with 3 instances running, two of which are 
> reporting the state of `REBALANCING` even after they have been running for 
> days. Restarting the application has no effect on the stream state.
> This seems suspect because each instance appears to be processing messages, 
> and the `kafka-consumer-groups` CLI tool reports no offset lag in any of the 
> partitions assigned to the `REBALANCING` consumers. Each partition seems to 
> be processing an equal amount of records too.
> Inspecting the `state.dir` on disk, it looks like the RocksDB state has been 
> built and hovers at the expected size on disk.
> This problem has persisted for us after we rebuilt our Kafka cluster and 
> reset topics + consumer groups in our dev environment.
> There is nothing in the logs (with level set to `DEBUG`) in both the broker 
> or the application that suggests something exceptional has happened causing 
> the application to be stuck `REBALANCING`
> We are also running multiple streaming applications where this problem does 
> not exist.
> Two differences between this application and our other streaming applications 
> are:
>  * We have `processing.guarantee` set to `exactly_once`
>  * We are using a `ValueTransformer` which fetches from and puts data on a 
> windowed state store
> The `REBALANCING` state is returned from both polling the `state` method of 
> our `KafkaStreams` instance, and our custom metric which is derived from some 
> logic in a `KafkaStreams.StateListener` class attached via the 
> `setStateListener` method.
>  
> While I have provided a bit of context, before I reply with some reproducible 
> code - is there a simple way in which I can determine that my streams 
> application is in a `RUNNING` state without relying on the same mechanisms as 
> used above?
> Further, given that it seems like my application is actually running - could 
> this perhaps be a bug to do with how the stream state is being reported (in 
> the context of a transactional stream using the processor API)?
>  
>  
>  
>  



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