- Scheduler's CycleState now embeds internal read/write locking inside its `Read()` and `Write()` functions. Meanwhile, `Lock()` and `Unlock()` function are removed. Scheduler plugin developers are now required to remove `CycleState#Lock()` and `CycleState#Unlock()`. Just simply use `Read()` and `Write()` as they're natively thread-safe now. ([#101542](https://github.com/kubernetes/kubernetes/pull/101542), [@Huang-Wei](https://github.com/Huang-Wei))...

<code>E</code>
[<a href="#Go_1.18">Go 1.18</a>].
</p>

<pre>
type Reader interface {
	Read(p []byte) (n int, err error)
	Close() error
}

type Writer interface {
	Write(p []byte) (n int, err error)
	Close() error
}

// ReadWriter's methods are Read, Write, and Close.
type ReadWriter interface {
	Reader  // includes methods of Reader in ReadWriter's method set

  - The deprecated `--etcd-quorum-read` flag has been removed. Quorum reads are now always enabled when fetching data from etcd. Remove the `--etcd-quorum-read` flag from kube-apiserver invocations before upgrading.
- kube-controller-manager

    - [Container Images](#container-images-14)
  - [Changelog since v1.30.0](#changelog-since-v1300)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)
    - [(No, really, you MUST read this before you upgrade)](#no-really-you-must-read-this-before-you-upgrade)
  - [Changes by Kind](#changes-by-kind-14)
    - [Deprecation](#deprecation-1)
    - [API Change](#api-change-2)
    - [Feature](#feature-10)

* In GCE with COS, increase TasksMax for Docker service to raise cap on number of threads/processes used by containers. ([#51986](https://github.com/kubernetes/kubernetes/pull/51986), [@yujuhong](https://github.com/yujuhong))

    * controller REST client now uses that version.  For v1beta1, the API is now known as
    * resource-metrics.metrics.k8s.io.
* In GCE with COS, increase TasksMax for Docker service to raise cap on number of threads/processes used by containers. ([#51986](https://github.com/kubernetes/kubernetes/pull/51986), [@yujuhong](https://github.com/yujuhong))

### **API Machinery**

*   The kube-apiserver `--etcd-quorum-read` flag is deprecated and the ability to switch off quorum read will be removed in a future release. ([#53795](https://github.com/kubernetes/kubernetes/pull/53795),[ @xiangpengzhao](https://github.com/xiangpengzhao))

* In GCE with COS, increase TasksMax for Docker service to raise cap on number of threads/processes used by containers. ([#51986](https://github.com/kubernetes/kubernetes/pull/51986), [@yujuhong](https://github.com/yujuhong))