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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-16282) Semijoin: Disable slow-start for the bloom filter aggregate task
Date Wed, 22 Mar 2017 18:49:41 GMT
Gopal V created HIVE-16282:
------------------------------

             Summary: Semijoin: Disable slow-start for the bloom filter aggregate task
                 Key: HIVE-16282
                 URL: https://issues.apache.org/jira/browse/HIVE-16282
             Project: Hive
          Issue Type: Bug
    Affects Versions: 2.2.0
            Reporter: Gopal V


The slow-start of the bloom filter vertex is a scheduling problem which causes more pre-emption
than is useful.

When the bloom filters are arranged as follows

Map 1(10 tasks)->Reducer 2(1 task)->Map 3(100 tasks)

Map 3 and Map 1 are immediately active since Reducer 2 -> Map 3 is a broadcast edge.

Once 3 tasks in Map 1 finish, the engine kills one active task from Map 3 to make room for
Reducer 2.




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