Task each Mapper Performs

Question

I have a sql which has multiple joins.

2017-12-28 05:15:53,140 Map 1: 15/15    Map 6: 9/9  Map 7: 29/29    Map 8: 198(+2)/200  Map 9: 1/1  Reducer 2: 1/1  Reducer 3: 0(+1)/1  Reducer 4: 0(+3)/3  Reducer 5: 0(+11)/11

Above is the line from the log which is rnning for last few hours. How do I check what map 8 is doing and why 2 mappers are taking so long

map 8: 198(+2)/200

Any thoughts on what each mapper does in tez will help.

Answer 1

I would recommend you to look at DAG Graphical View/ Vertex Counter and analyze. You will get some insights on why a vertex is taking so long.