- The job controller back-off logic is now decoupled from workqueue. In case of parallelism > 1, if there are multiple new failures in a reconciliation cycle, all the failures are taken into account to compute the back-off. Previously, the back-off kicked in for all types of failures; with this change, only pod failures are taken into account. If the back-off limits exceeds, the job is marked as failed immediately; before this change, the...

- When the go-client reflector relists, the ResourceVersion list option is set to the reflector's latest synced resource version to ensure the reflector does not "go back in time" and reprocess events older than it has already processed. If the server responds with an HTTP 410 (Gone) status code response, the relist falls back to using `resourceVersion=""`. ([#83520](https://github.com/kubernetes/kubernetes/pull/83520), [@jpbetz](https://github.com/jpbetz))

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 registration...

* fix detach azure disk back off issue which has too big lock in failure retry condition ([#76573](https://github.com/kubernetes/kubernetes/pull/76573), [@andyzhangx](https://github.com/andyzhangx))

* fix network setup in hack/local-up-cluster.sh (https://github.com/kubernetes/kubernetes/pull/60431) ([#60633](https://github.com/kubernetes/kubernetes/pull/60633), [@pohly](https://github.com/pohly))
    * better error diagnostics in hack/local-up-cluster.sh output

### Other (Cleanup or Flake)

### Other (Cleanup or Flake)

- Reverts the EventedPLEG feature (beta, but disabled by default) back to alpha for a known issue ([#122719](https://github.com/kubernetes/kubernetes/pull/122719), [@pacoxu](https://github.com/pacoxu)) [SIG Node]

## Dependencies

### Added
_Nothing has changed._

  Previously, when unschedulable Pods are updated, the scheduler always put Pods back to activeQ/backoffQ. But, actually not all updates to Pods make Pods schedulable, especially considering many scheduling constraints nowadays are immutable.

### Other (Cleanup or Flake)

- Reverts the EventedPLEG feature (beta, but disabled by default) back to alpha for a known issue ([#122718](https://github.com/kubernetes/kubernetes/pull/122718), [@pacoxu](https://github.com/pacoxu)) [SIG Node]

## Dependencies

### Added
_Nothing has changed._

## 1.9 Release Notes

## WARNING: etcd backup strongly recommended

Before updating to 1.9, you are strongly recommended to back up your etcd data. Consult the installation procedure you are using (kargo, kops, kube-up, kube-aws, kubeadm etc) for specific advice.