Tsuyoshi OZAWA created MAPREDUCE-4863:
-----------------------------------------
Summary: 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
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
|