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https://issues.apache.org/jira/browse/HADOOP-10281?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14061070#comment-14061070
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Lei (Eddy) Xu commented on HADOOP-10281:
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[~chrili] Thank you for this great work. It looks nice overall. I only have a
few minor questions:
1. Does the latest design abandon the concept of the RPC window (e.g., tracking
latest 1000 RPCs)?
2. With the combination of a relatively larger {{decayPeriodMillis}} (i.e.,
inappropriate settings?), would it be possible that {{totalCount}} actually
increases for a long time？In this case, when there is a large {{totalCount}}
(e.g., 1M), it might be difficult to detect a burst traffic (e.g., 800 of the
latest 1000 RPCs from the same faulty user)?
3. Also, would the schedule cache be difficult to detect the same burst above?
What do you think?
> 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-preview.patch, HADOOP-10281.patch,
> 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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