Fixed a situation when, sometimes, the scheduler incorrectly placed a pod in the `unschedulable` queue instead of the `backoff` queue. This happened when some plugin previously declared the pod as `unschedulable` and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the `active` queue. ([#120334](https://github.com/kubernetes/kubernetes/pull/120334), [@pohly](https://github.com/pohly))...

        * `{WorkQueueName}_queue_latency`
        * `{WorkQueueName}_work_duration`
        * `{WorkQueueName}_unfinished_work_seconds`
        * `{WorkQueueName}_longest_running_processor_microseconds`
        * `{WorkQueueName}_retries`
    * Please convert to the following metrics:
        * `workqueue_depth`
        * `workqueue_adds_total`
        * `workqueue_queue_latency_seconds`

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active" queue. ([#120334](https://github.com/kubernetes/kubernetes/pull/120334), [@pohly](https://github.com/pohly))...

- Added a `Processing` condition for the `workqueue` API.
  Changed `Shutdown` for the `workqueue` API to wait until the work queue finishes processing all in-flight items. ([#101928](https://github.com/kubernetes/kubernetes/pull/101928), [@alexanderConstantinescu](https://github.com/alexanderConstantinescu))

- Sometimes, the scheduler incorrectly placed a pod in the "unschedulable" queue instead of the "backoff" queue. This happened when some plugin previously declared the pod as "unschedulable" and then in a later attempt encounters some other error. Scheduling of that pod then got delayed by up to five minutes, after which periodic flushing moved the pod back into the "active" queue. ([#120334](https://github.com/kubernetes/kubernetes/pull/120334), [@pohly](https://github.com/pohly))...

- Implement the scheduling framework with `Reserve`, `Prebind`, `Permit`, `Post-bind`, `Queue sort` and `Unreserve` extension points.
([#77567](https://github.com/kubernetes/kubernetes/pull/77567), [@wgliang](https://github.com/wgliang))

- Add a deprecated cmd flag for the time interval between flushing pods from unschedulable queue to active queue or backoff queue. ([#108017](https://github.com/kubernetes/kubernetes/pull/108017), [@denkensk](https://github.com/denkensk))