Tez holding last couple of Mappers too long

I have dynamic partition over union all query and last 2% (last couple of maps) take too long.

VERTICES STATUS TOTAL COMPLETED RUNNING PENDING FAILED KILLED
——————————————————————————–
Map 1 ………. SUCCEEDED 2 2 0 0 0 0
Map 10 ……… RUNNING 20 19 2 0 0 0
Map 11 ……… SUCCEEDED 2 2 0 0 0 0

something like this.