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From "Wangda Tan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-2297) Preemption can prevent progress in small queues
Date Sat, 19 Jul 2014 14:55:38 GMT

    [ https://issues.apache.org/jira/browse/YARN-2297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14067544#comment-14067544

Wangda Tan commented on YARN-2297:

bq. I feel this can create a little bit more starvation for queues configured with less capacity.
+1, this should not be reasonable
bq. Yes. This make more sense, it can neutralize ratio as well as difference to a uniform
way. I feel more sampling can be done to come with a better approach. i can check and update
I feel it should be a better way too, looking forward your update, we should make a fact-based
decision :)

> Preemption can prevent progress in small queues
> -----------------------------------------------
>                 Key: YARN-2297
>                 URL: https://issues.apache.org/jira/browse/YARN-2297
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: capacityscheduler
>    Affects Versions: 2.5.0
>            Reporter: Tassapol Athiapinya
>            Assignee: Wangda Tan
>            Priority: Critical
> Preemption can cause hang issue in single-node cluster. Only AMs run. No task container
can run.
> h3. queue configuration
> Queue A/B has 1% and 99% respectively. 
> No max capacity.
> h3. scenario
> Turn on preemption. Configure 1 NM with 4 GB of memory. Use only 2 apps. Use 1 user.
> Submit app 1 to queue A. AM needs 2 GB. There is 1 task that needs 2 GB. Occupy entire
> Submit app 2 to queue B. AM needs 2 GB. There are 3 tasks that need 2 GB each.
> Instead of entire app 1 preempted, app 1 AM will stay. App 2 AM will launch. No task
of either app can proceed. 
> h3. commands
> /usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop-mapreduce/hadoop-mapreduce-examples.jar
randomtextwriter "-Dmapreduce.map.memory.mb=2000" "-Dyarn.app.mapreduce.am.command-opts=-Xmx1800M"
"-Dmapreduce.randomtextwriter.bytespermap=2147483648" "-Dmapreduce.job.queuename=A" "-Dmapreduce.map.maxattempts=100"
"-Dmapreduce.am.max-attempts=1" "-Dyarn.app.mapreduce.am.resource.mb=2000" "-Dmapreduce.map.java.opts=-Xmx1800M"
"-Dmapreduce.randomtextwriter.mapsperhost=1" "-Dmapreduce.randomtextwriter.totalbytes=2147483648"
> /usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop-mapreduce/hadoop-mapreduce-client-jobclient-tests.jar
sleep "-Dmapreduce.map.memory.mb=2000" "-Dyarn.app.mapreduce.am.command-opts=-Xmx1800M" "-Dmapreduce.job.queuename=B"
"-Dmapreduce.map.maxattempts=100" "-Dmapreduce.am.max-attempts=1" "-Dyarn.app.mapreduce.am.resource.mb=2000"
"-Dmapreduce.map.java.opts=-Xmx1800M" -m 1 -r 0 -mt 4000  -rt 0

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