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https://issues.apache.org/jira/browse/KAFKA-13196?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jozef Vilcek updated KAFKA-13196:
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Summary: MirrorMaker 2 not always start tasks (was: MirrorMaker 2 not
always starting tasks)
> MirrorMaker 2 not always start tasks
> ------------------------------------
>
> Key: KAFKA-13196
> URL: https://issues.apache.org/jira/browse/KAFKA-13196
> Project: Kafka
> Issue Type: Bug
> Components: mirrormaker
> Affects Versions: 2.7.1
> Reporter: Jozef Vilcek
> Priority: Major
>
> I am using MirrorMaker 2.0 and running it via [
> MirrorMaker.java|https://github.com/apache/kafka/blob/2.7/connect/mirror/src/main/java/org/apache/kafka/connect/mirror/MirrorMaker.java]
> class. This method will start up `DistributedHerder` and will use
> non-functional `advertisedUrl`, and therefore workers can not talk to each
> other and coordinate.
> After upgrading from version `2.4.0` to `2.7.1` I did notice that when I am
> starting up mirror maker ti does not always start tasks - just connector is
> executing. Doing some amount of stop and start it will eventually start tasks
> too.
> After a bit of digging I did noticed that in attempt to configure connector's
> task, code ends up in this [1] branch, where configure request is being
> forwarded to the leader. From some reason, task configuration is not done on
> leader. However, MirrorMaker does not pack RestServer and therefore that
> request will never succeed.
> I am not sure what is going no or why it does seem to work better on 2.4.0. I
> noticed that connector start procedure did involve less callback on 2.4.0 in
> connector start sequence [2].
> I believe the root cause is change in startup procedure of connectors in
> general. In vestion 2.4, when connector is started by the leader here [1] it
> will immediately setup and submit configuration for connector's tasks.
> However, in 2.7.1, is it more asynchronous. Connector is started here [2]
> Does this look like a bug? Or am I doing something wrong?
>
> [1]
> https://github.com/apache/kafka/blob/2.7/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/distributed/DistributedHerder.java#L1494
> [2]
> https://github.com/apache/kafka/blob/2.4/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/distributed/DistributedHerder.java#L1236
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