[IMPALA-8805] Clarify behaviour around when resource pool config changes take effect

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Backend
• Labels: admission-control
• Target Version: Product Backlog
• Epic Color: ghx-label-3
• Assignee: Unassigned
• Reporter: Tim Armstrong
• Created: 29/Jul/19 17:05
• Updated: 11/Mar/20 17:28

Description

I spent some time playing around with resource pool configs and it's quite difficult to tell when a config change took effect - I at least was temporarily convinced that there was a bug where change were not picked up. I believe I was mistaken and just getting confused by the staleness of the /admission UI until a query is submitted by the pool, plus my query not getting routed to the right pool.

• Confirm that all resource pool config changes take effect dynamically when the next query is submitted
• Document this behaviour
• Investigate what it would take to reflect pool configs in the admission UI immediately when they take effect
• Add information to the debug UI that indicates that pool configs are correct as-of the last query submitted to the pool
• Maybe add logging when the config change is picked up
• Maybe add a warning when REQUEST_POOL is specified but the query does not end up in that pool (e.g. if the pool doesn't exist).