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From "Wangda Tan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-6050) AMs can't be scheduled on racks or nodes
Date Thu, 16 Feb 2017 23:12:41 GMT

    [ https://issues.apache.org/jira/browse/YARN-6050?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15870845#comment-15870845
] 

Wangda Tan commented on YARN-6050:
----------------------------------

Thanks [~rkanter],

Some comments:

1) {{RMAppImpl#createNewAttempt}}, we don't have to initialize BlacklistManager here, correct?
Since we will do this in ScheduledTransition. This can be done in a separate patch.
2) Changes in getApplicableNodeCountForAM doesn't get #Nodes correct, at least for following
cases: 
- If host1-3/rack1 have relaxLocality set to true, and host1-3 belongs to rack1, this method
get usable nodes = 3 + #rack1.
- If rack1 has 29 nodes, rack2 has 35 nodes, if relaxLocality set to true for both of them,
usable nodes = 35 instead of 29+35.
3) Not caused by your patch, but we'd better fix: {{ScheduleTransition}} happens only once
for every attempt, this won't get updated for node add/remove, it's better to periodically
update this. This can be done in a separate patch.


> AMs can't be scheduled on racks or nodes
> ----------------------------------------
>
>                 Key: YARN-6050
>                 URL: https://issues.apache.org/jira/browse/YARN-6050
>             Project: Hadoop YARN
>          Issue Type: Bug
>    Affects Versions: 2.9.0, 3.0.0-alpha2
>            Reporter: Robert Kanter
>            Assignee: Robert Kanter
>         Attachments: YARN-6050.001.patch, YARN-6050.002.patch, YARN-6050.003.patch, YARN-6050.004.patch,
YARN-6050.005.patch, YARN-6050.006.patch, YARN-6050.007.patch, YARN-6050.008.patch
>
>
> Yarn itself supports rack/node aware scheduling for AMs; however, there currently are
two problems:
> # To specify hard or soft rack/node requests, you have to specify more than one {{ResourceRequest}}.
 For example, if you want to schedule an AM only on "rackA", you have to create two {{ResourceRequest}},
like this:
> {code}
> ResourceRequest.newInstance(PRIORITY, ANY, CAPABILITY, NUM_CONTAINERS, false);
> ResourceRequest.newInstance(PRIORITY, "rackA", CAPABILITY, NUM_CONTAINERS, true);
> {code}
> The problem is that the Yarn API doesn't actually allow you to specify more than one
{{ResourceRequest}} in the {{ApplicationSubmissionContext}}.  The current behavior is to either
build one from {{getResource}} or directly from {{getAMContainerResourceRequest}}, depending
on if {{getAMContainerResourceRequest}} is null or not.  We'll need to add a third method,
say {{getAMContainerResourceRequests}}, which takes a list of {{ResourceRequest}} so that
clients can specify the multiple resource requests.
> # There are some places where things are hardcoded to overwrite what the client specifies.
 These are pretty straightforward to fix.



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