From 706e90a0339fae592a3854849548a5c2010b90ab Mon Sep 17 00:00:00 2001
From: Jun Gong <jungong@tencent.com>
Date: Fri, 13 Dec 2019 09:40:50 +0800
Subject: [PATCH] Skip scheduling the pod if it has been assumed and the pod
 updates could be skipped.

---
 pkg/scheduler/scheduler.go      | 23 ++++++++++++++++++++---
 pkg/scheduler/scheduler_test.go |  6 ++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/pkg/scheduler/scheduler.go b/pkg/scheduler/scheduler.go
index 2e0dc546b22..fc3863bc91f 100644
--- a/pkg/scheduler/scheduler.go
+++ b/pkg/scheduler/scheduler.go
@@ -599,9 +599,7 @@ func (sched *Scheduler) scheduleOne(ctx context.Context) {
 		return
 	}
 	pod := podInfo.Pod
-	if pod.DeletionTimestamp != nil {
-		sched.Recorder.Eventf(pod, nil, v1.EventTypeWarning, "FailedScheduling", "Scheduling", "skip schedule deleting pod: %v/%v", pod.Namespace, pod.Name)
-		klog.V(3).Infof("Skip schedule deleting pod: %v/%v", pod.Namespace, pod.Name)
+	if sched.skipPodSchedule(pod) {
 		return
 	}
 
@@ -764,6 +762,25 @@ func (sched *Scheduler) scheduleOne(ctx context.Context) {
 	}()
 }
 
+// skipPodSchedule returns true if we could skip scheduling the pod for specified cases.
+func (sched *Scheduler) skipPodSchedule(pod *v1.Pod) bool {
+	// Case 1: pod is being deleted.
+	if pod.DeletionTimestamp != nil {
+		sched.Recorder.Eventf(pod, nil, v1.EventTypeWarning, "FailedScheduling", "Scheduling", "skip schedule deleting pod: %v/%v", pod.Namespace, pod.Name)
+		klog.V(3).Infof("Skip schedule deleting pod: %v/%v", pod.Namespace, pod.Name)
+		return true
+	}
+
+	// Case 2: pod has been assumed and pod updates could be skipped.
+	// An assumed pod can be added again to the scheduling queue if it got an update event
+	// during its previous scheduling cycle but before getting assumed.
+	if sched.skipPodUpdate(pod) {
+		return true
+	}
+
+	return false
+}
+
 type podConditionUpdaterImpl struct {
 	Client clientset.Interface
 }
diff --git a/pkg/scheduler/scheduler_test.go b/pkg/scheduler/scheduler_test.go
index 1bb26fe59e8..1343abe3d2d 100644
--- a/pkg/scheduler/scheduler_test.go
+++ b/pkg/scheduler/scheduler_test.go
@@ -309,6 +309,12 @@ func TestScheduler(t *testing.T) {
 				AssumeFunc: func(pod *v1.Pod) {
 					gotAssumedPod = pod
 				},
+				IsAssumedPodFunc: func(pod *v1.Pod) bool {
+					if pod == nil || gotAssumedPod == nil {
+						return false
+					}
+					return pod.UID == gotAssumedPod.UID
+				},
 			}
 
 			s := &Scheduler{