querier: set minimum concurrency to 4 for query-scheduler's new querier-worker queue prioritization #9054
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chencs
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oh no that damn suggestion thing created a merge commit |
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…er-worker queue prioritization
Co-authored-by: Taylor C <[email protected]>
Co-authored-by: Taylor C <[email protected]>
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chencs
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chencs
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Aug 20, 2024
Yeah, I never actually use the suggestion thing (or do any code changes like resolve merge conflicts in-browser) for this reason, I just copy the suggested changes into my branch. I'm not sure if there's a better way, but I haven't found it. |
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Docstring for constant should be a sufficient description, but will expand a bit here:
When we move to a new RequestQueue dequeuing algorithm, we will modulo querier-worker IDs to distribute them across 4 request queue dimensions, one each for the "expected query component" which is assigned to the query request: ingester, store-gateway, both, or unknown.
Having querier-worker connections < num queue dimensions will result in queue starvation unless not all 4 queue dimensions are active. In any minimally utilized cluster, we expect all 4 dimensions will exist at almost all times.
Because the queriers have no centralized knowledge or coordination of how many queriers exist in the cluster, we must set a minimum of 4 for each querier<->request queue instance connection, where a "request queue instance" is a query-frontend or a query-scheduler.
What this PR does
Which issue(s) this PR fixes or relates to
Fixes #
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX].about-versioning.mdupdated with experimental features.