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https://issues.apache.org/jira/browse/MAPREDUCE-3902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13219552#comment-13219552
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Zhihong Yu commented on MAPREDUCE-3902:
---------------------------------------
{code}
+ private void makeContainerReuseDecision() {
+ targetMapContainers =
+ conf.getInt(MRJobConfig.MR_AM_CONTAINER_REUSE_MAX_CONTAINERS,
+ numMapTasks);
+ }
{code}
Maybe more logic is going to be added to the above method ?
{code}
+ // Key->Resource Capability
+ // Value->ResourceRequest
+ protected final Map<Priority, Map<String, ResourceRequest>>
remoteRequestsTable =
- new TreeMap<Priority, Map<String, Map<Resource, ResourceRequest>>>();
+ new HashMap<Priority, Map<String, ResourceRequest>>();
{code}
The comment above doesn't seem to match the Map structure.
> MR AM should reuse containers for map tasks, there-by allowing fine-grained
> control on num-maps for users without need for CombineFileInputFormat etc.
> ------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-3902
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3902
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: applicationmaster, mrv2
> Reporter: Arun C Murthy
> Assignee: Arun C Murthy
> Attachments: MAPREDUCE-3902.patch
>
>
> The MR AM is now in a great position to reuse containers across (map) tasks.
> This is something similar to JVM re-use we had in 0.20.x, but in a
> significantly better manner:
> # Consider data-locality when re-using containers
> # Consider the new shuffle - ensure that reduces fetch output of the whole
> container at once (i.e. all maps)
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