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https://issues.apache.org/jira/browse/SAMZA-947?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15281601#comment-15281601
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Yi Pan (Data Infrastructure) commented on SAMZA-947:
----------------------------------------------------
+1. Merged and submitted. Thanks!
> TaskAssignmentManager registration exception when partition count changes.
> --------------------------------------------------------------------------
>
> Key: SAMZA-947
> URL: https://issues.apache.org/jira/browse/SAMZA-947
> Project: Samza
> Issue Type: Bug
> Affects Versions: 0.10.1
> Reporter: Jake Maes
> Assignee: Jake Maes
> Priority: Minor
> Fix For: 0.10.1
>
> Attachments: SAMZA-947_1.patch, SAMZA-947_2.patch
>
>
> The GroupByPartitionCount grouper deletes the persisted task mapping if the
> partition count has changed because there may be fewer tasks and that would
> cause the old mapping to be invalid.
> To delete the mapping, the TaskAssignmentManager registers itself and writes
> null for all the keys. Later when the recalculated mapping is saved, it tries
> to reregister itself, which causes this exception:
> Exception in thread "main" org.apache.samza.SamzaException:
> SamzaTaskAssignmentManager is already registered with the queuing system
> producer
> at
> org.apache.samza.system.kafka.KafkaSystemProducer.register(KafkaSystemProducer.scala:65)
> at
> org.apache.samza.coordinator.stream.CoordinatorStreamSystemProducer.register(CoordinatorStreamSystemProducer.java:72)
> at
> org.apache.samza.coordinator.stream.AbstractCoordinatorStreamManager.registerCoordinatorStreamProducer(AbstractCoordinatorStreamManager.java:100)
> at
> org.apache.samza.container.grouper.task.TaskAssignmentManager.register(TaskAssignmentManager.java:58)
> at
> org.apache.samza.container.grouper.task.GroupByContainerCount.saveTaskAssignments(GroupByContainerCount.java:179)
> at
> org.apache.samza.container.grouper.task.GroupByContainerCount.balance(GroupByContainerCount.java:93)
> at
> org.apache.samza.coordinator.JobCoordinator$.refreshJobModel(JobCoordinator.scala:255)
> at
> org.apache.samza.coordinator.JobCoordinator$.jobModelGenerator$1(JobCoordinator.scala:187)
> at
> org.apache.samza.coordinator.JobCoordinator$.initializeJobModel(JobCoordinator.scala:193)
> at
> org.apache.samza.coordinator.JobCoordinator$.getJobCoordinator(JobCoordinator.scala:120)
> at
> org.apache.samza.coordinator.JobCoordinator$.apply(JobCoordinator.scala:104)
> at
> org.apache.samza.job.yarn.SamzaAppMaster$.main(SamzaAppMaster.scala:74)
> at org.apache.samza.job.yarn.SamzaAppMaster.main(SamzaAppMaster.scala)
> In a YARN environment, the AM restarts and since the task mapping has now
> been deleted, this 2nd attempt to save the mapping succeeds.
> Since this issue only occurs when the partition count changes and is
> recoverable, I'm marking it as low priority.
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