KCCM: fix slow node sync + service update

Author: alexanderConstantinescu

staging/src/k8s.io/cloud-provider/controllers/service/controller.go

@@ -93,10 +93,10 @@ type Controller struct {
 	serviceQueue workqueue.RateLimitingInterface
 	nodeQueue    workqueue.RateLimitingInterface
 	// lastSyncedNodes is used when reconciling node state and keeps track of
-	// the last synced set of nodes. This field is concurrently safe because the
-	// nodeQueue is serviced by only one go-routine, so node events are not
-	// processed concurrently.
-	lastSyncedNodes []*v1.Node
+	// the last synced set of nodes per service key. This is accessed from the
+	// service and node controllers, hence it is protected by a lock.
+	lastSyncedNodes     map[string][]*v1.Node
+	lastSyncedNodesLock sync.Mutex
 }
 
 // New returns a new service controller to keep cloud provider service resources
@@ -124,7 +124,7 @@ func New(
 		nodeListerSynced: nodeInformer.Informer().HasSynced,
 		serviceQueue:     workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(minRetryDelay, maxRetryDelay), "service"),
 		nodeQueue:        workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(minRetryDelay, maxRetryDelay), "node"),
-		lastSyncedNodes:  []*v1.Node{},
+		lastSyncedNodes:  make(map[string][]*v1.Node),
 	}
 
 	serviceInformer.Informer().AddEventHandlerWithResyncPeriod(
@@ -439,16 +439,32 @@ func (c *Controller) ensureLoadBalancer(ctx context.Context, service *v1.Service
 	if err != nil {
 		return nil, err
 	}
-
 	// If there are no available nodes for LoadBalancer service, make a EventTypeWarning event for it.
 	if len(nodes) == 0 {
 		c.eventRecorder.Event(service, v1.EventTypeWarning, "UnAvailableLoadBalancer", "There are no available nodes for LoadBalancer")
 	}
-
-	// - Only one protocol supported per service
 	// - Not all cloud providers support all protocols and the next step is expected to return
 	//   an error for unsupported protocols
-	return c.balancer.EnsureLoadBalancer(ctx, c.clusterName, service, nodes)
+	status, err := c.balancer.EnsureLoadBalancer(ctx, c.clusterName, service, nodes)
+	if err != nil {
+		return nil, err
+	}
+	c.storeLastSyncedNodes(service, nodes)
+	return status, nil
+}
+
+func (c *Controller) storeLastSyncedNodes(svc *v1.Service, nodes []*v1.Node) {
+	c.lastSyncedNodesLock.Lock()
+	defer c.lastSyncedNodesLock.Unlock()
+	key, _ := cache.MetaNamespaceKeyFunc(svc)
+	c.lastSyncedNodes[key] = nodes
+}
+
+func (c *Controller) getLastSyncedNodes(svc *v1.Service) []*v1.Node {
+	c.lastSyncedNodesLock.Lock()
+	defer c.lastSyncedNodesLock.Unlock()
+	key, _ := cache.MetaNamespaceKeyFunc(svc)
+	return c.lastSyncedNodes[key]
 }
 
 // ListKeys implements the interface required by DeltaFIFO to list the keys we
@@ -662,15 +678,6 @@ func portEqualForLB(x, y *v1.ServicePort) bool {
 	return true
 }
 
-func serviceKeys(services []*v1.Service) sets.String {
-	ret := sets.NewString()
-	for _, service := range services {
-		key, _ := cache.MetaNamespaceKeyFunc(service)
-		ret.Insert(key)
-	}
-	return ret
-}
-
 func nodeNames(nodes []*v1.Node) sets.String {
 	ret := sets.NewString()
 	for _, node := range nodes {
@@ -737,19 +744,29 @@ func (c *Controller) syncNodes(ctx context.Context, workers int) sets.String {
 // load balancers and finished doing it successfully, or didn't try to at all because
 // there's no need. This function returns true if we tried to update load balancers and
 // failed, indicating to the caller that we should try again.
-func (c *Controller) nodeSyncService(svc *v1.Service, oldNodes, newNodes []*v1.Node) bool {
+func (c *Controller) nodeSyncService(svc *v1.Service) bool {
 	const retSuccess = false
 	const retNeedRetry = true
 	if svc == nil || !wantsLoadBalancer(svc) {
 		return retSuccess
 	}
+	newNodes, err := listWithPredicates(c.nodeLister)
+	if err != nil {
+		runtime.HandleError(fmt.Errorf("failed to retrieve node list: %v", err))
+		nodeSyncErrorCount.Inc()
+		return retNeedRetry
+	}
 	newNodes = filterWithPredicates(newNodes, getNodePredicatesForService(svc)...)
-	oldNodes = filterWithPredicates(oldNodes, getNodePredicatesForService(svc)...)
-
+	oldNodes := filterWithPredicates(c.getLastSyncedNodes(svc), getNodePredicatesForService(svc)...)
+	// Store last synced nodes without actually determining if we successfully
+	// synced them or not. Failed node syncs are passed off to retries in the
+	// service queue, so no need to wait. If we don't store it now, we risk
+	// re-syncing all LBs twice, one from another sync in the node sync and
+	// from the service sync
+	c.storeLastSyncedNodes(svc, newNodes)
 	if nodesSufficientlyEqual(oldNodes, newNodes) {
 		return retSuccess
 	}
-
 	klog.V(4).Infof("nodeSyncService started for service %s/%s", svc.Namespace, svc.Name)
 	if err := c.lockedUpdateLoadBalancerHosts(svc, newNodes); err != nil {
 		runtime.HandleError(fmt.Errorf("failed to update load balancer hosts for service %s/%s: %v", svc.Namespace, svc.Name, err))
@@ -794,20 +811,12 @@ func nodesSufficientlyEqual(oldNodes, newNodes []*v1.Node) bool {
 func (c *Controller) updateLoadBalancerHosts(ctx context.Context, services []*v1.Service, workers int) (servicesToRetry sets.String) {
 	klog.V(4).Infof("Running updateLoadBalancerHosts(len(services)==%d, workers==%d)", len(services), workers)
 
-	// Include all nodes and let nodeSyncService filter and figure out if
-	// the update is relevant for the service in question.
-	nodes, err := listWithPredicates(c.nodeLister)
-	if err != nil {
-		runtime.HandleError(fmt.Errorf("failed to retrieve node list: %v", err))
-		return serviceKeys(services)
-	}
-
 	// lock for servicesToRetry
 	servicesToRetry = sets.NewString()
 	lock := sync.Mutex{}
 
 	doWork := func(piece int) {
-		if shouldRetry := c.nodeSyncService(services[piece], c.lastSyncedNodes, nodes); !shouldRetry {
+		if shouldRetry := c.nodeSyncService(services[piece]); !shouldRetry {
 			return
 		}
 		lock.Lock()
@@ -816,7 +825,6 @@ func (c *Controller) updateLoadBalancerHosts(ctx context.Context, services []*v1
 		servicesToRetry.Insert(key)
 	}
 	workqueue.ParallelizeUntil(ctx, workers, len(services), doWork)
-	c.lastSyncedNodes = nodes
 	klog.V(4).Infof("Finished updateLoadBalancerHosts")
 	return servicesToRetry
 }

staging/src/k8s.io/cloud-provider/controllers/service/controller_test.go

@@ -177,7 +177,7 @@ func newController(stopCh <-chan struct{}, objects ...runtime.Object) (*Controll
 		nodeListerSynced:    nodeInformer.Informer().HasSynced,
 		serviceQueue:        workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(minRetryDelay, maxRetryDelay), "service"),
 		nodeQueue:           workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(minRetryDelay, maxRetryDelay), "node"),
-		lastSyncedNodes:     []*v1.Node{},
+		lastSyncedNodes:     make(map[string][]*v1.Node),
 	}
 
 	informerFactory.Start(stopCh)
@@ -609,7 +609,10 @@ func TestNodeChangesForExternalTrafficPolicyLocalServices(t *testing.T) {
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
 
-			controller.lastSyncedNodes = tc.initialState
+			for _, svc := range services {
+				key, _ := cache.MetaNamespaceKeyFunc(svc)
+				controller.lastSyncedNodes[key] = tc.initialState
+			}
 
 			for _, state := range tc.stateChanges {
 				setupState := func() {
@@ -782,7 +785,10 @@ func TestNodeChangesForStableNodeSetEnabled(t *testing.T) {
 			ctx, cancel := context.WithCancel(context.Background())
 			defer cancel()
 
-			controller.lastSyncedNodes = tc.initialState
+			for _, svc := range services {
+				key, _ := cache.MetaNamespaceKeyFunc(svc)
+				controller.lastSyncedNodes[key] = tc.initialState
+			}
 
 			for _, state := range tc.stateChanges {
 				setupState := func() {
@@ -989,7 +995,10 @@ func TestNodesNotEqual(t *testing.T) {
 			defer cancel()
 			controller.nodeLister = newFakeNodeLister(nil, tc.newNodes...)
 
-			controller.lastSyncedNodes = tc.lastSyncNodes
+			for _, svc := range services {
+				key, _ := cache.MetaNamespaceKeyFunc(svc)
+				controller.lastSyncedNodes[key] = tc.lastSyncNodes
+			}
 
 			controller.updateLoadBalancerHosts(ctx, services, 5)
 			compareUpdateCalls(t, tc.expectedUpdateCalls, cloud.UpdateCalls)
@@ -1420,9 +1429,8 @@ func TestSlowNodeSync(t *testing.T) {
 		{Service: service1, Hosts: []*v1.Node{node1, node2}},
 		// Second update call for impacted service from controller.syncService
 		{Service: service2, Hosts: []*v1.Node{node1, node2, node3}},
-		// Third update call for second service from controller.syncNodes. Here
-		// is the problem: this update call removes the previously added node3.
-		{Service: service2, Hosts: []*v1.Node{node1, node2}},
+		// Third update call for second service from controller.syncNodes.
+		{Service: service2, Hosts: []*v1.Node{node1, node2, node3}},
 	}
 
 	wg := sync.WaitGroup{}