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From "Matthias J. Sax (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KAFKA-6437) Streams does not warn about missing input topics, but hangs
Date Fri, 23 Mar 2018 18:43:00 GMT

    [ https://issues.apache.org/jira/browse/KAFKA-6437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16411873#comment-16411873
] 

Matthias J. Sax commented on KAFKA-6437:
----------------------------------------

Sounds good to me. Feel free to work on this, [~johnma]. I think we can put this check into
{{KafkaStreams}} constructor and log a warning if input/output topics are missing.

> Streams does not warn about missing input topics, but hangs
> -----------------------------------------------------------
>
>                 Key: KAFKA-6437
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6437
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>    Affects Versions: 1.0.0
>         Environment: Single client on single node broker
>            Reporter: Chris Schwarzfischer
>            Priority: Minor
>              Labels: newbie
>
> *Case*
> Streams application with two input topics being used for a left join.
> When the left side topic is missing upon starting the streams application, it hangs "in
the middle" of the topology (at …00009, see below). Only parts of the intermediate topics
are created (up to …00009)
> When the missing input topic is created, the streams application resumes processing.
> {noformat}
> Topology:
> StreamsTask taskId: 2_0
> 	ProcessorTopology:
> 		KSTREAM-SOURCE-0000000011:
> 			topics:		[mystreams_app-KTABLE-AGGREGATE-STATE-STORE-0000000009-repartition]
> 			children:	[KTABLE-AGGREGATE-0000000012]
> 		KTABLE-AGGREGATE-0000000012:
> 			states:		[KTABLE-AGGREGATE-STATE-STORE-0000000009]
> 			children:	[KTABLE-TOSTREAM-0000000020]
> 		KTABLE-TOSTREAM-0000000020:
> 			children:	[KSTREAM-SINK-0000000021]
> 		KSTREAM-SINK-0000000021:
> 			topic:		data_udr_month_customer_aggregration
> 		KSTREAM-SOURCE-0000000017:
> 			topics:		[mystreams_app-KSTREAM-MAP-0000000014-repartition]
> 			children:	[KSTREAM-LEFTJOIN-0000000018]
> 		KSTREAM-LEFTJOIN-0000000018:
> 			states:		[KTABLE-AGGREGATE-STATE-STORE-0000000009]
> 			children:	[KSTREAM-SINK-0000000019]
> 		KSTREAM-SINK-0000000019:
> 			topic:		data_UDR_joined
> Partitions [mystreams_app-KSTREAM-MAP-0000000014-repartition-0, mystreams_app-KTABLE-AGGREGATE-STATE-STORE-0000000009-repartition-0]
> {noformat}
> *Why this matters*
> The applications does quite a lot of preprocessing before joining with the missing input
topic. This preprocessing won't happen without the topic, creating a huge backlog of data.
> *Fix*
> Issue an `warn` or `error` level message at start to inform about the missing topic and
it's consequences.



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