feat: introduce ControllerPriorityQueue feature gate

Signed-off-by: zach593 <[email protected]>

Author: zach593

cmd/agent/app/agent.go

@@ -34,6 +34,7 @@ import (
 	logsv1 "k8s.io/component-base/logs/api/v1"
 	"k8s.io/component-base/term"
 	"k8s.io/klog/v2"
+	"k8s.io/utils/ptr"
 	controllerruntime "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
 	"sigs.k8s.io/controller-runtime/pkg/config"
@@ -225,6 +226,7 @@ func run(ctx context.Context, opts *options.Options) error {
 				clusterv1alpha1.SchemeGroupVersion.WithKind("Cluster").GroupKind().String(): opts.ConcurrentClusterSyncs,
 			},
 			CacheSyncTimeout: opts.ClusterCacheSyncTimeout.Duration,
+			UsePriorityQueue: ptr.To(features.FeatureGate.Enabled(features.ControllerPriorityQueue)),
 		},
 		NewCache: func(config *rest.Config, opts cache.Options) (cache.Cache, error) {
 			opts.DefaultTransform = fedinformer.StripUnusedFields

cmd/controller-manager/app/controllermanager.go

@@ -38,6 +38,7 @@ import (
 	resourceclient "k8s.io/metrics/pkg/client/clientset/versioned/typed/metrics/v1beta1"
 	"k8s.io/metrics/pkg/client/custom_metrics"
 	"k8s.io/metrics/pkg/client/external_metrics"
+	"k8s.io/utils/ptr"
 	controllerruntime "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
 	"sigs.k8s.io/controller-runtime/pkg/config"
@@ -193,6 +194,7 @@ func Run(ctx context.Context, opts *options.Options) error {
 				schema.GroupVersionKind{Group: "", Version: "v1", Kind: "Namespace"}.GroupKind().String(): opts.ConcurrentNamespaceSyncs,
 			},
 			CacheSyncTimeout: opts.ClusterCacheSyncTimeout.Duration,
+			UsePriorityQueue: ptr.To(features.FeatureGate.Enabled(features.ControllerPriorityQueue)),
 		},
 		NewCache: func(config *rest.Config, opts cache.Options) (cache.Cache, error) {
 			opts.DefaultTransform = fedinformer.StripUnusedFields

pkg/features/features.go

@@ -113,6 +113,20 @@ const (
 	// owner: @mszacillo, @Dyex719, @RainbowMango, @XiShanYongYe-Chang, @zhzhuang-zju, @seanlaii
 	// alpha: v1.15
 	MultiplePodTemplatesScheduling featuregate.Feature = "MultiplePodTemplatesScheduling"
+
+	// ControllerPriorityQueue controls whether the controller-runtime Priority Queue for controllers is enabled.
+	// When enabled, during the startup phase of karmada-controller-manager and karmada-agent,
+	// controllers implemented with controller-runtime will prioritize processing recent cluster changes first,
+	// while deferring items without recent updates that still need to be processed to the end of the queue.
+	// This helps the system quickly catch up with the latest state and reduces the perceived
+	// backlog from external users.
+	// However, enabling this feature may increase the overall number of reconciliations. This is
+	// because newer events spend less time in the queue, which reduces the chance of them being
+	// deduplicated before processing.
+	//
+	// owner: @zach593
+	// alpha: v1.15
+	ControllerPriorityQueue featuregate.Feature = "ControllerPriorityQueue"
 )
 
 var (
@@ -139,6 +153,7 @@ var (
 		LoggingBetaOptions:                {Default: true, PreRelease: featuregate.Beta},
 		ContextualLogging:                 {Default: true, PreRelease: featuregate.Beta},
 		MultiplePodTemplatesScheduling:    {Default: false, PreRelease: featuregate.Alpha},
+		ControllerPriorityQueue:           {Default: false, PreRelease: featuregate.Alpha},
 	}
 )