[HIVE-17784] Make Tez AM's Queue headroom calculation and nParallel tasks configurable.

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2.0, 3.0.0
• Component/s: Query Planning, Tez
• Assignee: Mithun Radhakrishnan
• Reporter: Mithun Radhakrishnan
• Created: 12/Oct/17 06:40
• Updated: 12/Oct/17 18:15

Description

Here's a couple of customizations we made at Yahoo with Hive Tez AMs:

1. When calculating splits, HiveSplitGenerator takes the entire queue's capacity as available, and generates splits accordingly. While this greedy algorithm might be acceptable for exclusive queues, on a shared queue, greedy queries will hold other queries up. The algorithm that calculates the queue's headroom should be pluggable. The greedy version can be the default.
2. TEZ_AM_VERTEX_MAX_TASK_CONCURRENCY and the AM's heap-size can be tuned separately from the AM's container size. We found that users who attempt to increase vertex concurrency tend to forget to bump AM memory/container sizes. It would be handier if those values were derived from the container size.

I'm combining these into a single patch, for easier review.

(Note to self: YHIVE-840)