fix: requeue pods rejected by Extenders properly

pkg/scheduler/framework/runtime/framework.go

@@ -260,6 +260,14 @@ func NewFramework(ctx context.Context, r Registry, profile *config.KubeScheduler
 		logger:               logger,
 	}
 
+	if len(f.extenders) > 0 {
+		// Extender doesn't support any kind of requeueing feature like EnqueueExtensions in the scheduling framework.
+		// We register a defaultEnqueueExtension to framework.ExtenderName here.
+		// And, in the scheduling cycle, when Extenders reject some Nodes and the pod ends up being unschedulable,
+		// we put framework.ExtenderName to pInfo.UnschedulablePlugins.
+		f.enqueueExtensions = []framework.EnqueueExtensions{&defaultEnqueueExtension{pluginName: framework.ExtenderName}}
+	}
+
 	if profile == nil {
 		return f, nil
 	}