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Posted to issues@tez.apache.org by "Rajesh Balamohan (JIRA)" <ji...@apache.org> on 2015/04/03 01:14:57 UTC

[jira] [Assigned] (TEZ-2251) Enabling auto reduce parallelism in certain jobs causes DAG to hang

     [ https://issues.apache.org/jira/browse/TEZ-2251?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rajesh Balamohan reassigned TEZ-2251:
-------------------------------------

    Assignee: Rajesh Balamohan

> Enabling auto reduce parallelism in certain jobs causes DAG to hang
> -------------------------------------------------------------------
>
>                 Key: TEZ-2251
>                 URL: https://issues.apache.org/jira/browse/TEZ-2251
>             Project: Apache Tez
>          Issue Type: Bug
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>         Attachments: TEZ-2251.2.patch, TEZ-2251.3.patch, TEZ-2251.VertexImpl.patch, TEZ-2251.VertexImpl.readlock.patch, TEZ-2251.fix_but_slows_down.patch, hive_console.png, tez-2251.vertexpatch.am.log.gz, tez_2251_dag.png
>
>
> Scenario:
> - Run TPCH query20 (https://github.com/cartershanklin/hive-testbench/blob/master/sample-queries-tpch/tpch_query20.sql) at 1 TB scale (tez-master branch, hive trunk)
> - Enable auto reduce parallelism
> - DAG didn't complete and got stuck in "Reducer 6"
> Vertex parallelism of "Reducer 5 & 6" happens within a span of 3 milliseconds, and tasks of "reducer 5" ends up producing wrong partition details as it sees the updated task numbers of reducer 6 when scheduled.  This causes, job to hang.



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