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Posted to mapreduce-issues@hadoop.apache.org by "Tsuyoshi OZAWA (JIRA)" <ji...@apache.org> on 2013/01/04 09:14:14 UTC
[jira] [Updated] (MAPREDUCE-4863) Adding aggregationWaitMap for
node-level combiner.
[ https://issues.apache.org/jira/browse/MAPREDUCE-4863?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Tsuyoshi OZAWA updated MAPREDUCE-4863:
--------------------------------------
Attachment: 0002-Adding-aggregationWaitMap-for-node-level-combiner.patch
First patch.
> Adding aggregationWaitMap for node-level combiner.
> --------------------------------------------------
>
> Key: MAPREDUCE-4863
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4863
> Project: Hadoop Map/Reduce
> Issue Type: Sub-task
> Components: applicationmaster
> Affects Versions: 3.0.0
> Reporter: Tsuyoshi OZAWA
> Assignee: Tsuyoshi OZAWA
> Attachments: 0002-Adding-aggregationWaitMap-for-node-level-combiner.patch
>
>
> To manage node/rack-level combining, MRAppMaster needs to have a management information about outputs of completed MapTasks to be aggregated. AggregationWaitMap is used so that MRAppMaster decides whether or not MapTasks start to combine local MapOutputFiles.
> AggregationWaitMap is a abstraction class of ConcurrentHashMap<String, ArrayList<TaskAttemptCompletionEvent>. These Events are candidate files to be aggregated.
> When MapTasks are completed, MRAppMaster buffer TaskAttemptCompletionEvent into AggregationWaitMap to delay reducers' fethcing outputs from mappers until node-level aggregation are finished. After node-level aggreagtion, MRAppMaster write back mapAttemptCompletionEvents, to restart reducers' feching outputs from mappers.
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