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Posted to mapreduce-issues@hadoop.apache.org by "Karthik Kambatla (JIRA)" <ji...@apache.org> on 2014/11/22 00:01:34 UTC

[jira] [Updated] (MAPREDUCE-5785) Derive heap size or mapreduce.*.memory.mb automatically

     [ https://issues.apache.org/jira/browse/MAPREDUCE-5785?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Karthik Kambatla updated MAPREDUCE-5785:
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    Summary: Derive heap size or mapreduce.*.memory.mb automatically  (was: Derive task attempt JVM max heap size and io.sort.mb automatically from mapreduce.*.memory.mb)

> Derive heap size or mapreduce.*.memory.mb automatically
> -------------------------------------------------------
>
>                 Key: MAPREDUCE-5785
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5785
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>          Components: mr-am, task
>            Reporter: Gera Shegalov
>            Assignee: Gera Shegalov
>         Attachments: MAPREDUCE-5785.v01.patch, MAPREDUCE-5785.v02.patch, MAPREDUCE-5785.v03.patch, mr-5785-4.patch, mr-5785-5.patch
>
>
> Currently users have to set 2 memory-related configs per Job / per task type.  One first chooses some container size map reduce.\*.memory.mb and then a corresponding maximum Java heap size Xmx < map reduce.\*.memory.mb. This makes sure that the JVM's C-heap (native memory + Java heap) does not exceed this mapreduce.*.memory.mb. If one forgets to tune Xmx, MR-AM might be 
> - allocating big containers whereas the JVM will only use the default -Xmx200m.
> - allocating small containers that will OOM because Xmx is too high.
> With this JIRA, we propose to set Xmx automatically based on an empirical ratio that can be adjusted. Xmx is not changed automatically if provided by the user.



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