Cluster Size = 16GB [2NM's]
Queue A Capacity = 50%
Queue B Capacity = 50%
Consider there are 3 applications running in Queue A which has taken the full cluster capacity.
J1 = 2GB AM + 1GB * 4 Maps
J2 = 2GB AM + 1GB * 4 Maps
J3 = 2GB AM + 1GB * 2 Maps
Another Job J4 is submitted in Queue B [J4 needs a 2GB AM + 1GB * 2 Maps ].
Currently in this scenario, Jobs J3 will get killed including its AM.
It is better if AM can be given least priority among multiple applications. In this same scenario, map tasks from J3 and J2 can be preempted.
Later when cluster is free, maps can be allocated to these Jobs.