- CEL regex patterns in x-kubernetes-valiation rules are compiled when CRDs are created/updated if the pattern is provided as a string constant in the expression. Any regex compile errors are reported as a CRD create/update validation error. ([#108617](https://github.com/kubernetes/kubernetes/pull/108617), [@j...

- Added e2e tests for volume group snapshots. ([#128972](https://github.com/kubernetes/kubernetes/pull/128972), [@manishym](https://github.com/manishym)) [SIG Cloud Provider, Storage and Testing]
- Added unit test helpers to validate CEL and patterns in CustomResourceDefinitions. ([#129028](https://github.com/kubernetes/kubernetes/pull/129028), [@sttts](https://github.com/sttts))

- Added memory tracking to scheduler performance tests to help detect memory leaks and monitored memory usage patterns while running `scheduler_perf`. ([#132910](https://github.com/kubernetes/kubernetes/pull/132910), [@utam0k](https://github.com/utam0k)) [SIG Scheduling and Testing]

- client-go discovery clients constructed using `NewDiscoveryClientForConfig` or `NewDiscoveryClientForConfigOrDie` default to rate limits that cause normal discovery request patterns to take several seconds. This is fixed in https://issue.k8s.io/86168 and will be resolved in v1.17.1. As a workaround, the `Burst` value can be adjusted higher in the rest.Config passed into `NewDiscoveryClientForConfig` or `NewDiscoveryClientForConfigOrDie`....

  * Kubernetes now shares a single PID namespace among all containers in a pod when running with docker >= 1.13.1. This means processes can now signal processes in other containers in a pod, but it also means that the `kubectl exec {pod} kill 1` pattern will cause the Pod to be restarted rather than a single container. ([#45236](https://github.com/kubernetes/kubernetes/pull/45236), [@verb](https://github.com/verb))

    * the loop to correctly handle acquiring the write lock with deferred
    * unlock to run at that function's completion, following the normal
    * golang lock/deferred-unlock pattern.
* fix UnmountDevice failure on Windows ([#68608](https://github.com/kubernetes/kubernetes/pull/68608), [@andyzhangx](https://github.com/andyzhangx))

- CustomResourceDefinition with invalid regular expression in the pattern field of OpenAPI v3 validation schemas are no longer considered structural. ([#78453](https://github.com/kubernetes/kubernetes/pull/78453), [@sttts](https://github.com/sttts))

- Specifying the KUBE_TEST_REPO environment variable when e2e tests are executed will instruct the test infrastructure to load that image from a location within the specified repo, using a predefined pattern. ([#93510](https://github.com/kubernetes/kubernetes/pull/93510), [@smarterclayton](https://github.com/smarterclayton)) [SIG Testing]

- Introduce...

thousands of pods simultaneously across hundreds of nodes. Kubelets in this scenario can encounter temporarily increased latency of `delete pod` API calls -- above the target service level objective of 1 second. If you run clusters with this usage pattern and if pod deletion latency could be an issue for you, you might want to wait until the issue is resolved before you upgrade.

For more information and for updates on resolution of this issue, see [#51899](https://github.com/kubernete...