[ https://issues.apache.org/jira/browse/MAPREDUCE-4863?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Work on MAPREDUCE-4863 started by Tsuyoshi OZAWA. > 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. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira