- Run TPCH query20 (https://github.com/cartershanklin/hive-testbench/blob/master/sample-queries-tpch/tpch_query20.sql) at 1 TB scale (tez-master branch, hive trunk)
- Enable auto reduce parallelism
- DAG didn't complete and got stuck in "Reducer 6"
Vertex parallelism of "Reducer 5 & 6" happens within a span of 3 milliseconds, and tasks of "reducer 5" ends up producing wrong partition details as it sees the updated task numbers of reducer 6 when scheduled. This causes, job to hang.