[IMPALA-5662] Log all information relevant to admission control decision making

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 3.1.0
• Component/s: Backend
• Labels: admission-control observability resource-management supportability
• Target Version: Product Backlog
• Epic Color: ghx-label-1
• Assignee: Bikramjeet Vig
• Reporter: Balazs Jeszenszky
• Created: 13/Jul/17 20:51
• Updated: 29/May/18 19:14
• Resolved: 23/May/18 17:24

Description

Currently, when making a decision whether to admit a query or not, the log has the following format:

I0705 14:43:04.031771  7388 admission-controller.cc:442] Stats: agg_num_running=1, agg_num_queued=0, agg_mem_reserved=486.74 MB,  local_host(local_mem_admitted=0, num_admitted_running=0, num_queued=0, backend_mem_reserved=56.07 MB)

Since it's also possible to queue queries due to one node not being able to reserve the required memory, we should also log the max(backend_mem_reserved) across all nodes.