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Posted to issues@spark.apache.org by "Trystan Leftwich (JIRA)" <ji...@apache.org> on 2016/06/17 14:27:05 UTC

[jira] [Created] (SPARK-16017) YarnClientSchedulerBackend now registers backends as IPs instead of Hostnames which causes all tasks to run with RACK_LOCAL locality.

Trystan Leftwich created SPARK-16017:
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             Summary: YarnClientSchedulerBackend now registers backends as IPs instead of Hostnames which causes all tasks to run with RACK_LOCAL locality.
                 Key: SPARK-16017
                 URL: https://issues.apache.org/jira/browse/SPARK-16017
             Project: Spark
          Issue Type: Bug
            Reporter: Trystan Leftwich
            Priority: Critical


Since this change: [SPARK-15395|https://issues.apache.org/jira/browse/SPARK-15395]

When registering new executor backends it registers them as IPs instead of hostnames. This causes a flow on effect that when the Task manager is trying to figure out what Locality tasks should run at, no tasks can be run At the NODE_LOCAL level.

This specific call:
https://github.com/apache/spark/blob/branch-2.0/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala#L886

[pendingTasksForHost|https://github.com/apache/spark/blob/branch-2.0/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala#L886]  are all hostnames pulled from the DFS locations while [hasExecutorsAliveOnHost|https://github.com/apache/spark/blob/9b234b55d1b5e4a7c80e482b3e297bfb8b583a56/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala#L560], uses [executorsByHost|https://github.com/apache/spark/blob/branch-2.0/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala#L98], which are all IP's because they are populated from the RpcAddress.

As expected this causes significant performance problems, A simple count query will take 22 seconds, But if I revert the change from [SPARK-15395|https://issues.apache.org/jira/browse/SPARK-15395], tasks will run with NODE_LOCAL locality and the same count will take 3 seconds.



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