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Posted to common-issues@hadoop.apache.org by "Daryn Sharp (JIRA)" <ji...@apache.org> on 2017/02/03 18:58:51 UTC

[jira] [Updated] (HADOOP-14032) Reduce fair call queue priority inversion

     [ https://issues.apache.org/jira/browse/HADOOP-14032?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Daryn Sharp updated HADOOP-14032:
---------------------------------
    Status: Patch Available  (was: Open)

Forgot to submit...

> Reduce fair call queue priority inversion
> -----------------------------------------
>
>                 Key: HADOOP-14032
>                 URL: https://issues.apache.org/jira/browse/HADOOP-14032
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: ipc
>    Affects Versions: 2.7.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>         Attachments: HADOOP-14032.patch
>
>
> The fcq's round robin multiplexer actually rewards abusive users.  Queue consumers scan for a call from the roving multiplexer index to the lowest prio ring before wrapping around to the higher prio rings.
> Let's take a fcq with 4 priority rings.  Multiplexer shares per index are 8, 4, 2, 1.  
> All well behaved clients are operating in ring 0.  Bad client floods the server and drops to the lowest prio.  Unfortunately the service order gives 8 shares to the good clients, followed by 4+2+1=7 shares to the bad client.



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