[IMPALA-8830] Coordinator-only queries get queued when there are no executor groups

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Impala 3.3.0
• Fix Version/s: Impala 4.0.0
• Component/s: Backend
• Labels: admission-control resource-management
• Target Version: Impala 4.0.0
• Epic Color: ghx-label-1
• Assignee: Bikramjeet Vig
• Reporter: Tim Armstrong
• Created: 03/Aug/19 21:24
• Updated: 22/Jun/20 19:34
• Resolved: 22/Jun/20 19:34

Description

Reproduction:

tarmstrong@tarmstrong-box:~/Impala/incubator-impala$ start-impala-cluster.py -s1 --use_exclusive_coordinators;
[localhost:21000] default> select * from tpch.lineitem order by l_orderkey limit 5;
ERROR: Admission for query exceeded timeout 60000ms in pool default-pool. Queued reason: No healthy executor groups found for pool default-pool.
[localhost:21000] default> select 1;
ERROR: Admission for query exceeded timeout 60000ms in pool default-pool. Queued reason: No healthy executor groups found for pool default-pool.

I expected that the second query should run immediately since it doesn't actually need to be scheduled on any executors. I suspect this may be a regression from the executor group changes, but didn't confirm.