- Added Coordinated Leader Election as Alpha under the `CoordinatedLeaderElection` feature gate. With the feature enabled, the control plane can use LeaseCandidate objects (coordination.k8s.io/v1alpha1 API group) to participate in a leader election and let the kube-apiserver select the best instance according to some strategy. ([#124012](https://github.com/kubernetes/kubernetes/pull/124012),...

- Client-go: Optimized leaders renewing leases by updating leader lock optimistically without getting the record from the API server first. Also, a new metric `leader_election_slowpath_total` was added to allow users to monitor how many leader elections are updated non-optimistically.

- The deprecated flag `--lock-object-namespace` and `--lock-object-name` have been removed from kube-scheduler. Please use `--leader-elect-resource-namespace` and `--leader-elect-resource-name` or ComponentConfig instead to configure those parameters. ([#119130](https://github.com/kubernetes/kubernetes/pull/119130), [@SataQiu](https://github.com/SataQiu)) [SIG Scheduling]

- The `--leader-elect*` CLI args are now honored in scheduler. ([#105915](https://github.com/kubernetes/kubernetes/pull/105915), [@Huang-Wei](https://github.com/Huang-Wei))

- Fixed a scheduler panic due to internal cache inconsistency ([#71063](https://github.com/kubernetes/kubernetes/pull/71063), [@Huang-Wei](https://github.com/Huang-Wei))
- Report kube-scheduler unhealthy if leader election is deadlocked. ([#71085](https://github.com/kubernetes/kubernetes/pull/71085), [@bsalamat](https://github.com/bsalamat))

* kube-scheduler has been fixed to use `--leader-elect` option back to true (as it was in previous versions) ([#59732](https://github.com/kubernetes/kubernetes/pull/59732), [@dims](https://github.com/dims))

- Fixes a bug of identifying the correct containerd process. ([#97888](https://github.com/kubernetes/kubernetes/pull/97888), [@pacoxu](https://github.com/pacoxu))
- Fixes add-on manager leader election to use leases instead of endpoints, similar to what kube-controller-manager does in 1.20 ([#98968](https://github.com/kubernetes/kubernetes/pull/98968), [@liggitt](https://github.com/liggitt))

* Migrate controller-manager and scheduler to EndpointsLeases leader election. ([#84084](https://github.com/kubernetes/kubernetes/pull/84084), [@wojtek-t](https://github.com/wojtek-t))

    * faster handoff when a leader-elected process is gracefully terminated.
* Make volume binder resilient to races between main schedule loop and async binding operation  ([#72045](https://github.com/kubernetes/kubernetes/pull/72045), [@cofyc](https://github.com/cofyc))

* Fix kubelet errors in AArch64 with huge page sizes smaller than 1MiB ([#78495](https://github.com/kubernetes/kubernetes/pull/78495), [@odinuge](https://github.com/odinuge))
* kube-addon-manager has been updated to v9.0.2 to fix a bug in leader election (https://github.com/kubernetes/kubernetes/pull/80575) ([#80861](https://github.com/kubernetes/kubernetes/pull/80861), [@mborsz](https://github.com/mborsz))