Configuring the Fair Scheduler

The Fair Scheduler lets all applications run by default, but you can also limit the number of running applications per user and per queue through the configuration file. This can be useful when a user must submit hundreds of applications at once, or in general to improve performance if running too many applications at once would cause too much intermediate data to be created or too much context-switching. Limiting the applications does not cause any subsequently submitted applications to fail; it only causes them to wait in the scheduler's queue until earlier applications finish.

{$MAPR_HOME}/hadoop/hadoop-2.x/etc/hadoop/fair-scheduler.xml

The allocation file is reloaded every 10 seconds to refresh the scheduler with any modified settings that are specified in the file.