Allow for metrics to be exchanged between mapps and reduces
-----------------------------------------------------------
Key: MAPREDUCE-3520
URL: https://issues.apache.org/jira/browse/MAPREDUCE-3520
Project: Hadoop Map/Reduce
Issue Type: New Feature
Components: mrv2
Affects Versions: 0.24.0
Reporter: Robert Joseph Evans
Some people on the mailing lists have requested having read access in reducers
to counters that were set by mappers. I propose that we provide a new
interface for doing this. The counter data in addition to being set
periodically to the Application Master would be put into the intermediate
output of the mapper for each reducer and be specially marked as such. When
the reducers fetch that data they can combine it together and provide a read
only interface to it.
This allows users to potentially optimize their code on the reducer side if
they know some special metadata before hand.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
