- Fixes the bug in PodTopologySpread that only happens with QHint enabled, 

    val snapshot = cache["b"]!!
    snapshot.close()
    assertThat(cache.edit("d")).isNull()
    assertThat(taskFaker.isIdle()).isFalse()

    // On cache misses, no retry job is queued.
    assertThat(cache["c"]).isNull()
    assertThat(taskFaker.isIdle()).isFalse()

    // Let the rebuild complete successfully.
    filesystem.setFaultyRename(cacheDir / DiskLruCache.JOURNAL_FILE_BACKUP, false)

- 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))...

- Previously, the scheduling queue didn't notice any extenders' failures, potentially resulting in missed cluster events and Pods rejected by Extenders being stuck in the unschedulable pod pool for up to 5 minutes in the worst-case scenario. Now, the scheduling queue notices extenders' failures and requeues Pods rejected by Extenders appropriately.

    @Synchronized
    override fun dispatch(request: RecordedRequest): MockResponse {
      // This guarantees a deterministic sequence when handling the canceled request:
      // 1. Server reads request and dequeues first response
      // 2. Client cancels request
      // 3. Server tries to send response on the canceled stream
      // Otherwise, there is no guarantee for the sequence. For example, the server may use the

### Scheduling

- Improved fairness of the scheduling queue by placing pods which are attempted recently behind other pods with the same priority. ([#73700](https://github.com/kubernetes/kubernetes/pull/73700), [@denkensk](https://github.com/denkensk))

* Change default value of deleting-pods-burst to 1 ([#27606](https://github.com/kubernetes/kubernetes/pull/27606), [@gmarek](https://github.com/gmarek))
* MESOS: fix race condition in contrib/mesos/pkg/queue/delay ([#24916](https://github.com/kubernetes/kubernetes/pull/24916), [@jdef](https://github.com/jdef))

### **Instrumentation**

#### **Audit**

*   Adjust batching audit webhook default parameters: increase queue size, batch size, and initial backoff. Add throttling to the batching audit webhook. Default rate limit is 10 QPS. ([#53417](https://github.com/kubernetes/kubernetes/pull/53417),[ @crassirostris](https://github.com/crassirostris))

- Added `SchedulerPopFromBackoffQ` feature gate that is in beta and enabled by default. Improved scheduling queue behavior by popping pods from the backoffQ when the activeQ is empty. This allows to process potentially schedulable pods ASAP, eliminating a penalty effect of the backoff queue. ([#130772](https://github.com/kubernetes/kubernetes/pull/130772), [@macsko](https://github.com/macsko)) [SIG Scheduling and Testing]

    - `scheduler_async_api_call_duration_seconds`: histogram of API call execution duration by call type and result
    - `scheduler_pending_async_api_calls`: gauge showing current number of pending API calls in the queue. ([#133120](https://github.com/kubernetes/kubernetes/pull/133120), [@utam0k](https://github.com/utam0k)) [SIG Release and Scheduling]