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Date: Thu, 23 Jun 2016 21:20:16 +0000 (UTC)
From: "Kuhu Shukla (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
Message-ID: <JIRA.12906251.1445350957000.14763.1466716816323@Atlassian.JIRA>
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References: <JIRA.12906251.1445350957000@Atlassian.JIRA> <JIRA.12906251.1445350957309@arcas>
Subject: [jira] [Updated] (YARN-4280) CapacityScheduler reservations may not
 prevent indefinite postponement on a busy cluster
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archived-at: Thu, 23 Jun 2016 21:20:18 -0000


     [ https://issues.apache.org/jira/browse/YARN-4280?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kuhu Shukla updated YARN-4280:
------------------------------
    Attachment: YARN-4280.005.patch

Attaching the intended patch.

> CapacityScheduler reservations may not prevent indefinite postponement on a busy cluster
> ----------------------------------------------------------------------------------------
>
>                 Key: YARN-4280
>                 URL: https://issues.apache.org/jira/browse/YARN-4280
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacity scheduler
>    Affects Versions: 2.6.1, 2.8.0, 2.7.1
>            Reporter: Kuhu Shukla
>            Assignee: Kuhu Shukla
>         Attachments: YARN-4280.001.patch, YARN-4280.002.patch, YARN-4280.003.patch, YARN-4280.004.patch, YARN-4280.005.patch
>
>
> Consider the following scenario:
> There are 2 queues A(25% of the total capacity) and B(75%), both can run at total cluster capacity. There are 2 applications, appX that runs on Queue A, always asking for 1G containers(non-AM) and appY runs on Queue B asking for 2 GB containers.
> The user limit is high enough for the application to reach 100% of the cluster resource. 
> appX is running at total cluster capacity, full with 1G containers releasing only one container at a time. appY comes in with a request of 2GB container but only 1 GB is free. Ideally, since appY is in the underserved queue, it has higher priority and should reserve for its 2 GB request. Since this request puts the alloc+reserve above total capacity of the cluster, reservation is not made. appX comes in with a 1GB request and since 1GB is still available, the request is allocated. 
> This can continue indefinitely causing priority inversion.


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