focused on stability and performance improvements in the 1.13 release.  A new alpha feature is introduced to improve the mechanism that nodes heartbeat back to the control plane.  The `NodeLease` feature results in the node using a `Lease` resource in the `kube-node-lease` namespace that is renewed periodically.  The `NodeStatus` that was used previously to heartbeat back to the control plane is only updated when it changes.  This reduces load on the control plane for large clusters. The Kubelet plugin...

- 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),...

- 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]

* Performance test framework and basic tests for the IPAM controller, to simulate behavior of the four supported modes under lightly loaded and loaded conditions, where load is defined as the number of operations to perform as against the configured kubernetes. ([#61143](https://github.com/kubernetes/kubernetes/pull/61143), [@satyasm](https://github.com/satyasm))

executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from or
based on this library.  If you modify this library, you may extend this

* The leaderelection package allows the lease holder to release its lease when the calling context is cancelled. This allows ([#71490](https://github.com/kubernetes/kubernetes/pull/71490), [@smarterclayton](https://github.com/smarterclayton))
    * faster handoff when a leader-elected process is gracefully terminated.

### Feature

- Add flag --lease-max-object-size and metric etcd_lease_object_counts for kube-apiserver to config and observe max objects attached to a single etcd lease. ([#97480](https://github.com/kubernetes/kubernetes/pull/97480), [@lingsamuel](https://github.com/lingsamuel)) [SIG API Machinery, Instrumentation and Scalability]

* kube-scheduler: restores default leader election behavior. leader-elect command line parameter should "true" ([#60524](https://github.com/kubernetes/kubernetes/pull/60524), [@dims](https://github.com/dims))

- 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 memory leak in endpointSliceTracker ([#92838](https://github.com/kubernetes/kubernetes/pull/92838), [@tnqn](https://github.com/tnqn)) [SIG Apps and Network]