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From "Apache Spark (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SPARK-17648) TaskSchedulerImpl.resourceOffers should take an IndexedSeq, not a Seq
Date Fri, 23 Sep 2016 19:34:20 GMT

     [ https://issues.apache.org/jira/browse/SPARK-17648?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Apache Spark reassigned SPARK-17648:
------------------------------------

    Assignee: Imran Rashid  (was: Apache Spark)

> TaskSchedulerImpl.resourceOffers should take an IndexedSeq, not a Seq
> ---------------------------------------------------------------------
>
>                 Key: SPARK-17648
>                 URL: https://issues.apache.org/jira/browse/SPARK-17648
>             Project: Spark
>          Issue Type: Improvement
>          Components: Scheduler, Spark Core
>    Affects Versions: 2.0.0
>            Reporter: Imran Rashid
>            Assignee: Imran Rashid
>            Priority: Minor
>
> {{TaskSchedulerImpl.resourceOffer}} takes in a {{Seq[WorkerOffer]}}.  however, later
on it indexes into this by position.  If you don't pass in an {{IndexedSeq}}, this turns an
O(n) operation in an O(n^2) operation.
> In practice, this isn't an issue, since just by chance the important places this is called,
the datastructures happen to already be {{IndexedSeq}} s.  But we ought to tighten up the
types to make this more clear.  I ran into this while doing some performance tests on the
scheduler, and performance was terrible when I passed in a {{Seq}} and even a few hundred
offers were scheduled very slowly.



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