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https://issues.apache.org/jira/browse/HADOOP-10281?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Li reassigned HADOOP-10281:
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Assignee: Chris Li
> Create a scheduler, which assigns schedulables a priority level
> ---------------------------------------------------------------
>
> Key: HADOOP-10281
> URL: https://issues.apache.org/jira/browse/HADOOP-10281
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Chris Li
> Assignee: Chris Li
> Attachments: HADOOP-10281.patch, HADOOP-10281.patch
>
>
> The Scheduler decides which sub-queue to assign a given Call. It implements a
> single method getPriorityLevel(Schedulable call) which returns an integer
> corresponding to the subqueue the FairCallQueue should place the call in.
> The HistoryRpcScheduler is one such implementation which uses the username of
> each call and determines what % of calls in recent history were made by this
> user.
> It is configured with a historyLength (how many calls to track) and a list of
> integer thresholds which determine the boundaries between priority levels.
> For instance, if the scheduler has a historyLength of 8; and priority
> thresholds of 4,2,1; and saw calls made by these users in order:
> Alice, Bob, Alice, Alice, Bob, Jerry, Alice, Alice
> * Another call by Alice would be placed in queue 3, since she has already
> made >= 4 calls
> * Another call by Bob would be placed in queue 2, since he has >= 2 but less
> than 4 calls
> * A call by Carlos would be placed in queue 0, since he has no calls in the
> history
> Also, some versions of this patch include the concept of a 'service user',
> which is a user that is always scheduled high-priority. Currently this seems
> redundant and will probably be removed in later patches, since its not too
> useful.
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