Repository: kubernetes/kubernetes (language: go)

Issue:
Filter gated pods before calling isPodWorthRequeueing
#### What type of PR is this?

/kind bug

#### What this PR does / why we need it:
When there are many gated pods and many events which trigger requeueing from the unschedulable pool (e.g. [deletePodFromCache](https://github.com/kubernetes/kubernetes/blob/72524fa574c58e08a5e1f3334aad7c8a8889d5a0/pkg/scheduler/eventhandlers.go#L254)) , we observe increased scheduling latency. We mitigate this issue by exiting before hitting the hotspots identified in #124384.

#### Which issue(s) this PR fixes:
Fixes #124384

/sig scheduling
#### Special notes for your reviewer:

#### Does this PR introduce a user-facing change?
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```release-note
Improved scheduling latency when many gated pods
```

#### Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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Discussion / hints:
This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the `triage/accepted` label and provide further guidance.

The `triage/accepted` label can be added by org members by writing `/triage accepted` in a comment.


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Welcome @gabesaba! <br><br>It looks like this is your first PR to <a href='https://github.com/kubernetes/kubernetes'>kubernetes/kubernetes</a> 🎉. Please refer to our [pull request process documentation](https://git.k8s.io/community/contributors/guide/pull-requests.md) to help your PR have a smooth ride to approval. <br><br>You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. [Here is the bot commands documentation](https://go.k8s.io/bot-commands). <br><br>You can also check if kubernetes/kubernetes has [its own contribution guidelines](https://github.com/kubernetes/kubernetes/tree/master/CONTRIBUTING.md). <br><br>You may want to refer to our [testing guide](https://git.k8s.io/community/contributors/devel/sig-testing/testing.md) if you run into trouble with your tests not passing. <br><br>If you are having difficulty getting your pull request seen, please follow the [recommended escalation practices](https://github.com/kubernetes/community/blob/master/contributors/guide/pull-requests.md#why-is-my-pull-request-not-getting-reviewed). Also, for tips and tricks in the contribution process you may want to read the [Kubernetes contributor cheat sheet](https://git.k8s.io/community/contributors/guide/contributor-cheatsheet/README.md). We want to make sure your contribution gets all the attention it needs! <br><br>Thank you, and welcome to Kubernetes. :smiley:
Hi @gabesaba. Thanks for your PR.

I'm waiting for a [kubernetes](https://github.com/orgs/kubernetes/people) member to verify that this patch is reasonable to test. If it is, they should reply with `/ok-to-test` on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should [join the org](https://git.k8s.io/community/community-membership.md#member) to skip this step.

Once the patch is verified, the new status will be reflected by the `ok-to-test` label.

I understand the commands that are listed [here](https://go.k8s.io/bot-commands?repo=kubernetes%2Fkubernetes).

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/ok-to-test
@sanposhiho do you want to give it a pass?
> But, can we move `TestGatedPodSchedulableAfterEvent` and `Test_queuedPodInfo_gatedSetUponCreationAndUnsetUponUpdate` in a different PR? I cannot relate them to the core change.

I asked for a change of this nature. Since we are changing how we are processing gated pods, I wanted to make sure they are still scheduled after a delete event for a different pod.

TestGatedPodSchedulableAfterEvent is ok then, but Test_queuedPodInfo_gatedSetUponCreationAndUnsetUponUpdate doesn't go thru any changed part at all.
Right, it can be added in a separate PR, so that it's not part of the cherry-pick.
/retest
LGTM label has been added.  <details>Git tree hash: 231011af712388280ca884c98f940ed9ad17f3d9</details>
[APPROVALNOTIFIER] This PR is **APPROVED**

This pull-request has been approved by: *<a href="https://github.com/kubernetes/kubernetes/pull/124618#pullrequestreview-2048462019" title="Approved">alculquicondor</a>*, *<a href="https://github.com/kubernetes/kubernetes/pull/124618#" title="Author self-approved">gabesaba</a>*

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<details >
Needs approval from an approver in each of these files:

- ~~[pkg/scheduler/OWNERS](https://github.com/kubernetes/kubernetes/blob/master/pkg/scheduler/OWNERS)~~ [alculquicondor]
- ~~[test/integration/scheduler/OWNERS](https://github.com/kubernetes/kubernetes/blob/master/test/integration/scheduler/OWNERS)~~ [alculquicondor]

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<!-- META={"approvers":[]} -->

Fix patch:
diff --git a/pkg/scheduler/internal/queue/scheduling_queue.go b/pkg/scheduler/internal/queue/scheduling_queue.go
index c50d853ba6ca7..83c7aeee99c72 100644
--- a/pkg/scheduler/internal/queue/scheduling_queue.go
+++ b/pkg/scheduler/internal/queue/scheduling_queue.go
@@ -1143,6 +1143,11 @@ func (p *PriorityQueue) requeuePodViaQueueingHint(logger klog.Logger, pInfo *fra
 func (p *PriorityQueue) movePodsToActiveOrBackoffQueue(logger klog.Logger, podInfoList []*framework.QueuedPodInfo, event framework.ClusterEvent, oldObj, newObj interface{}) {
 	activated := false
 	for _, pInfo := range podInfoList {
+		// Since there may be many gated pods and they will not move from the
+		// unschedulable pool, we skip calling the expensive isPodWorthRequeueing.
+		if pInfo.Gated {
+			continue
+		}
 		schedulingHint := p.isPodWorthRequeuing(logger, pInfo, event, oldObj, newObj)
 		if schedulingHint == queueSkip {
 			// QueueingHintFn determined that this Pod isn't worth putting to activeQ or backoffQ by this event.


Test patch:
diff --git a/pkg/scheduler/internal/queue/scheduling_queue_test.go b/pkg/scheduler/internal/queue/scheduling_queue_test.go
index 0f1c2a40c51af..bbf6f61f49862 100644
--- a/pkg/scheduler/internal/queue/scheduling_queue_test.go
+++ b/pkg/scheduler/internal/queue/scheduling_queue_test.go
@@ -95,6 +95,11 @@ var (
 	}
 )
 
+func setQueuedPodInfoGated(queuedPodInfo *framework.QueuedPodInfo) *framework.QueuedPodInfo {
+	queuedPodInfo.Gated = true
+	return queuedPodInfo
+}
+
 func getUnschedulablePod(p *PriorityQueue, pod *v1.Pod) *v1.Pod {
 	pInfo := p.unschedulablePods.get(pod)
 	if pInfo != nil {
@@ -1314,6 +1319,14 @@ func TestPriorityQueue_MoveAllToActiveOrBackoffQueueWithQueueingHint(t *testing.
 			hint:      queueHintReturnSkip,
 			expectedQ: unschedulablePods,
 		},
+		{
+			name:    "QueueHintFunction is not called when Pod is gated",
+			podInfo: setQueuedPodInfoGated(&framework.QueuedPodInfo{PodInfo: mustNewPodInfo(p), UnschedulablePlugins: sets.New("foo")}),
+			hint: func(logger klog.Logger, pod *v1.Pod, oldObj, newObj interface{}) (framework.QueueingHint, error) {
+				return framework.Queue, fmt.Errorf("QueueingHintFn should not be called as pod is gated")
+			},
+			expectedQ: unschedulablePods,
+		},
 	}
 
 	for _, test := range tests {
@@ -2483,7 +2496,7 @@ func TestPendingPodsMetric(t *testing.T) {
 	gated := makeQueuedPodInfos(total-queueableNum, "y", failme, timestamp)
 	// Manually mark them as gated=true.
 	for _, pInfo := range gated {
-		pInfo.Gated = true
+		setQueuedPodInfoGated(pInfo)
 	}
 	pInfos = append(pInfos, gated...)
 	totalWithDelay := 20
diff --git a/test/integration/scheduler/plugins/plugins_test.go b/test/integration/scheduler/plugins/plugins_test.go
index 791d1bdd72536..9803d9e8c9f60 100644
--- a/test/integration/scheduler/plugins/plugins_test.go
+++ b/test/integration/scheduler/plugins/plugins_test.go
@@ -2669,7 +2669,7 @@ func TestSchedulingGatesPluginEventsToRegister(t *testing.T) {
 		{
 			name:          "preEnqueue plugin with event registered",
 			enqueuePlugin: &SchedulingGatesPluginWithEvents{SchedulingGates: schedulinggates.SchedulingGates{EnablePodSchedulingReadiness: true}},
-			count:         3,
+			count:         2,
 		},
 	}
 
diff --git a/test/integration/scheduler/queue_test.go b/test/integration/scheduler/queue_test.go
index 42535552916a9..80802454e758d 100644
--- a/test/integration/scheduler/queue_test.go
+++ b/test/integration/scheduler/queue_test.go
@@ -56,12 +56,13 @@ import (
 
 func TestSchedulingGates(t *testing.T) {
 	tests := []struct {
-		name                  string
-		pods                  []*v1.Pod
-		featureEnabled        bool
-		want                  []string
-		rmPodsSchedulingGates []int
-		wantPostGatesRemoval  []string
+		name           string
+		pods           []*v1.Pod
+		featureEnabled bool
+		want           []string
+		delete         []string
+		unschedulable  []string
+		rmGates        []string
 	}{
 		{
 			name: "feature disabled, regular pods",
@@ -98,6 +99,7 @@ func TestSchedulingGates(t *testing.T) {
 			},
 			featureEnabled: true,
 			want:           []string{"p2"},
+			unschedulable:  []string{"p1"},
 		},
 		{
 			name: "feature enabled, two pod carrying scheduling gates, and remove gates of one pod",
@@ -106,10 +108,22 @@ func TestSchedulingGates(t *testing.T) {
 				st.MakePod().Name("p2").SchedulingGates([]string{"bar"}).Container("pause").Obj(),
 				st.MakePod().Name("p3").Container("pause").Obj(),
 			},
-			featureEnabled:        true,
-			want:                  []string{"p3"},
-			rmPodsSchedulingGates: []int{1}, // remove gates of 'p2'
-			wantPostGatesRemoval:  []string{"p2"},
+			featureEnabled: true,
+			want:           []string{"p3"},
+			unschedulable:  []string{"p1", "p2"},
+			rmGates:        []string{"p2"},
+		},
+		{
+			name: "gated pod schedulable after deleting the scheduled pod and removing gate",
+			pods: []*v1.Pod{
+				st.MakePod().Name("p1").SchedulingGates([]string{"foo"}).Container("pause").Obj(),
+				st.MakePod().Name("p2").Container("pause").Obj(),
+			},
+			featureEnabled: true,
+			want:           []string{"p2"},
+			delete:         []string{"p2"},
+			unschedulable:  []string{"p1"},
+			rmGates:        []string{"p1"},
 		},
 	}
 
@@ -130,6 +144,15 @@ func TestSchedulingGates(t *testing.T) {
 			testutils.SyncSchedulerInformerFactory(testCtx)
 
 			cs, ns, ctx := testCtx.ClientSet, testCtx.NS.Name, testCtx.Ctx
+
+			// Create node, so we can schedule pods.
+			node := st.MakeNode().Name("node").Obj()
+			if _, err := cs.CoreV1().Nodes().Create(ctx, node, metav1.CreateOptions{}); err != nil {
+				t.Fatal("Failed to create node")
+
+			}
+
+			// Create pods.
 			for _, p := range tt.pods {
 				p.Namespace = ns
 				if _, err := cs.CoreV1().Pods(ns).Create(ctx, p, metav1.CreateOptions{}); err != nil {
@@ -145,30 +168,44 @@ func TestSchedulingGates(t *testing.T) {
 				t.Fatal(err)
 			}
 
-			// Pop the expected pods out. They should be de-queueable.
-			for _, wantPod := range tt.want {
-				podInfo := testutils.NextPodOrDie(t, testCtx)
-				if got := podInfo.Pod.Name; got != wantPod {
-					t.Errorf("Want %v to be popped out, but got %v", wantPod, got)
+			go testCtx.Scheduler.Run(ctx)
+
+			// Verify pods scheduled.
+			for _, podName := range tt.want {
+				if err := wait.PollUntilContextTimeout(ctx, time.Millisecond*200, wait.ForeverTestTimeout, false, testutils.PodScheduled(cs, ns, podName)); err != nil {
+					t.Fatalf("Failed to schedule %s", podName)
+				}
+			}
+
+			// Delete pods, which triggers AssignedPodDelete event in the scheduling queue.
+			for _, podName := range tt.delete {
+				if err := cs.CoreV1().Pods(ns).Delete(ctx, podName, metav1.DeleteOptions{}); err != nil {
+					t.Fatalf("Error calling Delete on %s", podName)
+				}
+				if err := wait.PollUntilContextTimeout(ctx, time.Millisecond*200, wait.ForeverTestTimeout, false, testutils.PodDeleted(ctx, cs, ns, podName)); err != nil {
+					t.Fatalf("Failed to delete %s", podName)
 				}
 			}
 
-			if len(tt.rmPodsSchedulingGates) == 0 {
-				return
+			// Verify gated pods unschedulable.
+			for _, podName := range tt.unschedulable {
+				if err := wait.PollUntilContextTimeout(ctx, time.Millisecond*200, wait.ForeverTestTimeout, false, testutils.PodSchedulingGated(cs, ns, podName).WithContext()); err != nil {
+					t.Fatalf("Failed to verify unschedulable %s", podName)
+				}
 			}
+
 			// Remove scheduling gates from the pod spec.
-			for _, idx := range tt.rmPodsSchedulingGates {
+			for _, podName := range tt.rmGates {
 				patch := `{"spec": {"schedulingGates": null}}`
-				podName := tt.pods[idx].Name
 				if _, err := cs.CoreV1().Pods(ns).Patch(ctx, podName, types.StrategicMergePatchType, []byte(patch), metav1.PatchOptions{}); err != nil {
 					t.Fatalf("Failed to patch pod %v: %v", podName, err)
 				}
 			}
-			// Pop the expected pods out. They should be de-queueable.
-			for _, wantPod := range tt.wantPostGatesRemoval {
-				podInfo := testutils.NextPodOrDie(t, testCtx)
-				if got := podInfo.Pod.Name; got != wantPod {
-					t.Errorf("Want %v to be popped out, but got %v", wantPod, got)
+
+			// Verify pods without gates scheduled.
+			for _, podName := range tt.rmGates {
+				if err := wait.PollUntilContextTimeout(ctx, time.Millisecond*200, wait.ForeverTestTimeout, false, testutils.PodScheduled(cs, ns, podName)); err != nil {
+					t.Fatalf("Failed to schedule %s", podName)
 				}
 			}
 		})