Map tasks with no locality hints should not always be considered off-rack
-------------------------------------------------------------------------
Key: MAPREDUCE-2388
URL: https://issues.apache.org/jira/browse/MAPREDUCE-2388
Project: Hadoop Map/Reduce
Issue Type: Bug
Components: jobtracker
Reporter: Todd Lipcon
When a map task has no locality hints, it's currently always considered
"off-rack". This has a couple side effects which aren't great, most notably
that most schedulers will only assign one off-rack task per heartbeat. This
limits the scheduling throughput of these jobs.
It's unclear that it's always correct to schedule them as "node-local" either,
though most examples I can think of are probably better treated this way.
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
