[release-0.17] MultiKueue: one slow remote no longer stalls every other cluster#11333
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k8s-ci-robot merged 3 commits intoMay 19, 2026
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The single controller wide write lock in setRemoteClientConfig used to be held across the synchronous remote watch establishment in setConfig, which can take minutes against an unresponsive or warming apiserver. While that lock is held, every other MultiKueueCluster reconcile that calls setRemoteClientConfig blocks, so one slow remote stalls admission for every other cluster regardless of GroupKindConcurrency. Narrow the controller wide lock to just the remoteClients map find or insert, then serialize setConfig with a per cluster sync.Mutex on remoteClient. Concurrent reconciles for different clusters now run in parallel under their own locks. Same cluster reconciles still serialize through the workqueue dedup contract; the per cluster lock is belt and suspenders. Adds TestSetRemoteClientConfigDoesNotBlockOtherClusters which pins the property: while one cluster is parked inside its remote Watch call, another cluster's setRemoteClientConfig still completes. Refs 11297.
Per @mimowo's review, factor the map find or insert out of setRemoteClientConfig so each function uses the simple Lock(); defer Unlock() pattern instead of a manual unlock in the middle.
Per @mimowo's review on the test: - use Reconcile as the entry point instead of calling setRemoteClientConfig directly, so the test stays valid if watches ever get triggered from a different path - replace the magic 2s timeouts with a named stuckWatchTimeout = 5s so they survive a loaded CI runner
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: k8s-infra-cherrypick-robot, mimowo The full list of commands accepted by this bot can be found here. The pull request process is described here DetailsNeeds approval from an approver in each of these files:
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This is an automated cherry-pick of #11305
/assign mimowo