taintManager的主要功能为：当某个node被打上NoExecute污点后，其上面的pod如果不能容忍该污点，则taintManager将会驱逐这些pod，而新建的pod也需要容忍该污点才能调度到该node上；

(相关资料图)

通过kcm启动参数--enable-taint-manager来确定是否启动taintManager，true时启动（启动参数默认值为true）；

kcm启动参数--feature-gates=TaintBasedEvictions=xxx，默认值true，配合--enable-taint-manager共同作用，两者均为true，才会开启污点驱逐；

当node出现NoExecute污点时，判断node上的pod是否能容忍node的污点，不能容忍的pod，会被立即删除，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，pod被删除；

NoExecuteTaintManager结构体为taintManager的主要结构体，其主要属性有：（1）taintEvictionQueue：不能容忍node上NoExecute的污点的pod，会被加入到该队列中，然后pod会被删除；（2）taintedNodes：记录了每个node的taint；（3）nodeUpdateQueue：当node对象发生add、delete、update（新旧node对象的taint不相同）事件时，node会进入该队列；（4）podUpdateQueue：当pod对象发生add、delete、update（新旧pod对象的NodeName或Tolerations不相同）事件时，pod会进入该队列；（5）nodeUpdateChannels：nodeUpdateChannels即8个nodeUpdateItem类型的channel，有worker负责消费nodeUpdateQueue队列，然后根据node name计算出index，把node放入其中1个nodeUpdateItem类型的channel中；（6）podUpdateChannels：podUpdateChannels即8个podUpdateItem类型的channel，有worker负责消费podUpdateQueue队列，然后根据pod的node name计算出index，把pod放入其中1个podUpdateItem类型的channel中；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gotype NoExecuteTaintManager struct {client                clientset.Interfacerecorder              record.EventRecordergetPod                GetPodFuncgetNode               GetNodeFuncgetPodsAssignedToNode GetPodsByNodeNameFunctaintEvictionQueue *TimedWorkerQueue// keeps a map from nodeName to all noExecute taints on that NodetaintedNodesLock sync.MutextaintedNodes     map[string][]v1.TaintnodeUpdateChannels []chan nodeUpdateItempodUpdateChannels  []chan podUpdateItemnodeUpdateQueue workqueue.InterfacepodUpdateQueue  workqueue.Interface}

taintEvictionQueue属性是一个TimedWorkerQueue类型的队列，调用tc.taintEvictionQueue.AddWork，会将pod添加到该队列中，会添加一个定时器，然后到期之后会自动执行workFunc，初始化taintEvictionQueue时，传入的workFunc是deletePodHandler函数，作用是删除pod；

所以进入taintEvictionQueue中的pod，会在设置好的时间，被删除；

pod.Spec.Tolerations配置的是pod的污点容忍信息；

// vendor/k8s.io/api/core/v1/types.gotype Toleration struct {Key string `json:"key,omitempty" protobuf:"bytes,1,opt,name=key"`Operator TolerationOperator `json:"operator,omitempty" protobuf:"bytes,2,opt,name=operator,casttype=TolerationOperator"`Value string `json:"value,omitempty" protobuf:"bytes,3,opt,name=value"`Effect TaintEffect `json:"effect,omitempty" protobuf:"bytes,4,opt,name=effect,casttype=TaintEffect"`TolerationSeconds *int64 `json:"tolerationSeconds,omitempty" protobuf:"varint,5,opt,name=tolerationSeconds"`}

Tolerations的属性值解析如下：（1）Key：匹配node污点的Key；（2）Operator：表示Tolerations中Key与node污点的Key相同时，其Value与node污点的Value的关系，默认值Equal，代表相等，Exists则代表Tolerations中Key与node污点的Key相同即可，不用比较其Value值；（3）Value：匹配node污点的Value；（4）Effect：匹配node污点的Effect；（5）TolerationSeconds：node污点容忍时间；

配置示例：

tolerations:- key: "key1"  operator: "Equal"  value: "value1"  effect: "NoExecute"  tolerationSeconds: 3600

上述配置表示如果该pod正在运行，同时一个匹配的污点被添加到其所在的node节点上，那么该pod还将继续在节点上运行3600秒，然后会被驱逐（如果在此之前其匹配的node污点被删除了，则该pod不会被驱逐）；

NewNodeLifecycleController为NodeLifecycleController的初始化函数，里面给taintManager注册了pod与node的EventHandler，Add、Update、Delete事件都会调用taintManager的PodUpdated或NodeUpdated方法来做处理；

// pkg/controller/nodelifecycle/node_lifecycle_controller.gofunc NewNodeLifecycleController(    ...    podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{AddFunc: func(obj interface{}) {...if nc.taintManager != nil {nc.taintManager.PodUpdated(nil, pod)}},UpdateFunc: func(prev, obj interface{}) {...if nc.taintManager != nil {nc.taintManager.PodUpdated(prevPod, newPod)}},DeleteFunc: func(obj interface{}) {...if nc.taintManager != nil {nc.taintManager.PodUpdated(pod, nil)}},})    ...    if nc.runTaintManager {podGetter := func(name, namespace string) (*v1.Pod, error) { return nc.podLister.Pods(namespace).Get(name) }nodeLister := nodeInformer.Lister()nodeGetter := func(name string) (*v1.Node, error) { return nodeLister.Get(name) }nc.taintManager = scheduler.NewNoExecuteTaintManager(kubeClient, podGetter, nodeGetter, nc.getPodsAssignedToNode)nodeInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{AddFunc: nodeutil.CreateAddNodeHandler(func(node *v1.Node) error {nc.taintManager.NodeUpdated(nil, node)return nil}),UpdateFunc: nodeutil.CreateUpdateNodeHandler(func(oldNode, newNode *v1.Node) error {nc.taintManager.NodeUpdated(oldNode, newNode)return nil}),DeleteFunc: nodeutil.CreateDeleteNodeHandler(func(node *v1.Node) error {nc.taintManager.NodeUpdated(node, nil)return nil}),})}...}

tc.NodeUpdated方法会判断新旧node对象的taint是否相同，不相同则调用tc.nodeUpdateQueue.Add，将该node放入到nodeUpdateQueue队列中；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) NodeUpdated(oldNode *v1.Node, newNode *v1.Node) {nodeName := ""oldTaints := []v1.Taint{}if oldNode != nil {nodeName = oldNode.NameoldTaints = getNoExecuteTaints(oldNode.Spec.Taints)}newTaints := []v1.Taint{}if newNode != nil {nodeName = newNode.NamenewTaints = getNoExecuteTaints(newNode.Spec.Taints)}if oldNode != nil && newNode != nil && helper.Semantic.DeepEqual(oldTaints, newTaints) {return}updateItem := nodeUpdateItem{nodeName: nodeName,}tc.nodeUpdateQueue.Add(updateItem)}

tc.PodUpdated方法会判断新旧pod对象的NodeName或Tolerations是否相同，不相同则调用tc.podUpdateQueue.Add，将该pod放入到podUpdateQueue队列中；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) PodUpdated(oldPod *v1.Pod, newPod *v1.Pod) {podName := ""podNamespace := ""nodeName := ""oldTolerations := []v1.Toleration{}if oldPod != nil {podName = oldPod.NamepodNamespace = oldPod.NamespacenodeName = oldPod.Spec.NodeNameoldTolerations = oldPod.Spec.Tolerations}newTolerations := []v1.Toleration{}if newPod != nil {podName = newPod.NamepodNamespace = newPod.NamespacenodeName = newPod.Spec.NodeNamenewTolerations = newPod.Spec.Tolerations}if oldPod != nil && newPod != nil && helper.Semantic.DeepEqual(oldTolerations, newTolerations) && oldPod.Spec.NodeName == newPod.Spec.NodeName {return}updateItem := podUpdateItem{podName:      podName,podNamespace: podNamespace,nodeName:     nodeName,}tc.podUpdateQueue.Add(updateItem)}

看到TaintManager的初始化方法NewNoExecuteTaintManager中，调用CreateWorkerQueue给taintEvictionQueue做了初始化；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc NewNoExecuteTaintManager(...) ... {    ...    tm.taintEvictionQueue = CreateWorkerQueue(deletePodHandler(c, tm.emitPodDeletionEvent))    ...}

CreateWorkerQueue函数初始化并返回TimedWorkerQueue结构体；

// pkg/controller/nodelifecycle/scheduler/timed_workers.gofunc CreateWorkerQueue(f func(args *WorkArgs) error) *TimedWorkerQueue {return &TimedWorkerQueue{workers:  make(map[string]*TimedWorker),workFunc: f,}}

初始化taintEvictionQueue时传入了deletePodHandler作为队列中元素的处理方法；deletePodHandler函数的主要逻辑是请求apiserver，删除pod对象，所以说，被放入到taintEvictionQueue队列中的pod，会被删除；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc deletePodHandler(c clientset.Interface, emitEventFunc func(types.NamespacedName)) func(args *WorkArgs) error {return func(args *WorkArgs) error {ns := args.NamespacedName.Namespacename := args.NamespacedName.Nameklog.V(0).Infof("NoExecuteTaintManager is deleting Pod: %v", args.NamespacedName.String())if emitEventFunc != nil {emitEventFunc(args.NamespacedName)}var err errorfor i := 0; i < retries; i++ {err = c.CoreV1().Pods(ns).Delete(name, &metav1.DeleteOptions{})if err == nil {break}time.Sleep(10 * time.Millisecond)}return err}}

再来看一下tc.taintEvictionQueue.AddWork方法，作用是添加pod进入taintEvictionQueue队列，即调用CreateWorker给该pod创建一个worker来删除该pod；

// pkg/controller/nodelifecycle/scheduler/timed_workers.gofunc (q *TimedWorkerQueue) AddWork(args *WorkArgs, createdAt time.Time, fireAt time.Time) {key := args.KeyFromWorkArgs()klog.V(4).Infof("Adding TimedWorkerQueue item %v at %v to be fired at %v", key, createdAt, fireAt)q.Lock()defer q.Unlock()if _, exists := q.workers[key]; exists {klog.Warningf("Trying to add already existing work for %+v. Skipping.", args)return}worker := CreateWorker(args, createdAt, fireAt, q.getWrappedWorkerFunc(key))q.workers[key] = worker}

CreateWorker函数会先判断是否应该立即执行workFunc，是的话立即拉起一个goroutine来执行workFunc并返回，否则定义一个timer定时器，到时间后自动拉起一个goroutine执行workFunc；

// pkg/controller/nodelifecycle/scheduler/timed_workers.gofunc CreateWorker(args *WorkArgs, createdAt time.Time, fireAt time.Time, f func(args *WorkArgs) error) *TimedWorker {delay := fireAt.Sub(createdAt)if delay <= 0 {go f(args)return nil}timer := time.AfterFunc(delay, func() { f(args) })return &TimedWorker{WorkItem:  args,CreatedAt: createdAt,FireAt:    fireAt,Timer:     timer,}}

tc.taintEvictionQueue.AddWork方法，作用是停止对应的pod的timer，即停止执行对应pod的workFunc（不删除pod）；

// pkg/controller/nodelifecycle/scheduler/timed_workers.gofunc (w *TimedWorker) Cancel() {if w != nil {w.Timer.Stop()}}

nc.taintManager.Run为taintManager的启动方法，处理逻辑都在这，主要是判断node上的pod是否能容忍node的NoExecute污点，不能容忍的pod，会被删除，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，被删除；

主要逻辑：（1）创建8个类型为nodeUpdateItem的channel（缓冲区大小10），并赋值给tc.nodeUpdateChannels；创建8个类型为podUpdateItem的channel（缓冲区大小1），并赋值给podUpdateChannels；

（2）消费tc.nodeUpdateQueue队列，根据node name计算hash，将node放入对应的tc.nodeUpdateChannels[hash]中；

（3）消费tc.podUpdateQueue队列，根据pod的node name计算hash，将node放入对应的tc.podUpdateChannels[hash]中；

（4）启动8个goroutine，调用tc.worker对其中一个tc.nodeUpdateChannels与tc.podUpdateChannels做处理，判断node上的pod是否能容忍node的NoExecute污点，不能容忍的pod，会被删除，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，被删除；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) Run(stopCh <-chan struct{}) {klog.V(0).Infof("Starting NoExecuteTaintManager")for i := 0; i < UpdateWorkerSize; i++ {tc.nodeUpdateChannels = append(tc.nodeUpdateChannels, make(chan nodeUpdateItem, NodeUpdateChannelSize))tc.podUpdateChannels = append(tc.podUpdateChannels, make(chan podUpdateItem, podUpdateChannelSize))}// Functions that are responsible for taking work items out of the workqueues and putting them// into channels.go func(stopCh <-chan struct{}) {for {item, shutdown := tc.nodeUpdateQueue.Get()if shutdown {break}nodeUpdate := item.(nodeUpdateItem)hash := hash(nodeUpdate.nodeName, UpdateWorkerSize)select {case <-stopCh:tc.nodeUpdateQueue.Done(item)returncase tc.nodeUpdateChannels[hash] <- nodeUpdate:// tc.nodeUpdateQueue.Done is called by the nodeUpdateChannels worker}}}(stopCh)go func(stopCh <-chan struct{}) {for {item, shutdown := tc.podUpdateQueue.Get()if shutdown {break}// The fact that pods are processed by the same worker as nodes is used to avoid races// between node worker setting tc.taintedNodes and pod worker reading this to decide// whether to delete pod.// It"s possible that even without this assumption this code is still correct.podUpdate := item.(podUpdateItem)hash := hash(podUpdate.nodeName, UpdateWorkerSize)select {case <-stopCh:tc.podUpdateQueue.Done(item)returncase tc.podUpdateChannels[hash] <- podUpdate:// tc.podUpdateQueue.Done is called by the podUpdateChannels worker}}}(stopCh)wg := sync.WaitGroup{}wg.Add(UpdateWorkerSize)for i := 0; i < UpdateWorkerSize; i++ {go tc.worker(i, wg.Done, stopCh)}wg.Wait()}

tc.worker方法负责消费nodeUpdateChannels和podUpdateChannels，分别调用tc.handleNodeUpdate和tc.handlePodUpdate方法做进一步处理；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) worker(worker int, done func(), stopCh <-chan struct{}) {defer done()// When processing events we want to prioritize Node updates over Pod updates,// as NodeUpdates that interest NoExecuteTaintManager should be handled as soon as possible -// we don"t want user (or system) to wait until PodUpdate queue is drained before it can// start evicting Pods from tainted Nodes.for {select {case <-stopCh:returncase nodeUpdate := <-tc.nodeUpdateChannels[worker]:tc.handleNodeUpdate(nodeUpdate)tc.nodeUpdateQueue.Done(nodeUpdate)case podUpdate := <-tc.podUpdateChannels[worker]:// If we found a Pod update we need to empty Node queue first.priority:for {select {case nodeUpdate := <-tc.nodeUpdateChannels[worker]:tc.handleNodeUpdate(nodeUpdate)tc.nodeUpdateQueue.Done(nodeUpdate)default:break priority}}// After Node queue is emptied we process podUpdate.tc.handlePodUpdate(podUpdate)tc.podUpdateQueue.Done(podUpdate)}}}

tc.handleNodeUpdate方法主要是判断node上的pod是否能容忍node的NoExecute污点，不能容忍的pod，会被删除，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，被删除；

主要逻辑：（1）从informer本地缓存中获取node对象；（2）从node.Spec.Taints中获取NoExecute的taints；（3）将该node的NoExecute的taints更新到tc.taintedNodes中；（4）调用tc.getPodsAssignedToNode，获取该node上的所有pod，如果pod数量为0，直接return；（5）如果node的NoExecute的taints数量为0，则遍历该node上所有pod，调用tc.cancelWorkWithEvent，将该pod从taintEvictionQueue队列中移除，然后直接return；（6）遍历该node上所有pod，调用tc.processPodOnNode，对pod做进一步处理；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) handleNodeUpdate(nodeUpdate nodeUpdateItem) {node, err := tc.getNode(nodeUpdate.nodeName)if err != nil {if apierrors.IsNotFound(err) {// Deleteklog.V(4).Infof("Noticed node deletion: %#v", nodeUpdate.nodeName)tc.taintedNodesLock.Lock()defer tc.taintedNodesLock.Unlock()delete(tc.taintedNodes, nodeUpdate.nodeName)return}utilruntime.HandleError(fmt.Errorf("cannot get node %s: %v", nodeUpdate.nodeName, err))return}// Create or Updateklog.V(4).Infof("Noticed node update: %#v", nodeUpdate)taints := getNoExecuteTaints(node.Spec.Taints)func() {tc.taintedNodesLock.Lock()defer tc.taintedNodesLock.Unlock()klog.V(4).Infof("Updating known taints on node %v: %v", node.Name, taints)if len(taints) == 0 {delete(tc.taintedNodes, node.Name)} else {tc.taintedNodes[node.Name] = taints}}()// This is critical that we update tc.taintedNodes before we call getPodsAssignedToNode:// getPodsAssignedToNode can be delayed as long as all future updates to pods will call// tc.PodUpdated which will use tc.taintedNodes to potentially delete delayed pods.pods, err := tc.getPodsAssignedToNode(node.Name)if err != nil {klog.Errorf(err.Error())return}if len(pods) == 0 {return}// Short circuit, to make this controller a bit faster.if len(taints) == 0 {klog.V(4).Infof("All taints were removed from the Node %v. Cancelling all evictions...", node.Name)for i := range pods {tc.cancelWorkWithEvent(types.NamespacedName{Namespace: pods[i].Namespace, Name: pods[i].Name})}return}now := time.Now()for _, pod := range pods {podNamespacedName := types.NamespacedName{Namespace: pod.Namespace, Name: pod.Name}tc.processPodOnNode(podNamespacedName, node.Name, pod.Spec.Tolerations, taints, now)}}

tc.processPodOnNode方法主要作用是判断pod是否能容忍node上所有的NoExecute的污点，如果不能，则将该pod加到taintEvictionQueue队列中，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，加到taintEvictionQueue队列中；

主要逻辑：（1）如果node的NoExecute的taints数量为0，则调用tc.cancelWorkWithEvent，将该pod从taintEvictionQueue队列中移除；（2）调用v1helper.GetMatchingTolerations，判断pod是否容忍node上所有的NoExecute的taints，以及获取能容忍taints的容忍列表；（3）如果不能容忍所有污点，则调用tc.taintEvictionQueue.AddWork，将该pod加到taintEvictionQueue队列中；（4）如果能容忍所有污点，则等待所有污点的容忍时间里最小值后，再调用tc.taintEvictionQueue.AddWork，将该pod加到taintEvictionQueue队列中；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) processPodOnNode(podNamespacedName types.NamespacedName,nodeName string,tolerations []v1.Toleration,taints []v1.Taint,now time.Time,) {if len(taints) == 0 {tc.cancelWorkWithEvent(podNamespacedName)}allTolerated, usedTolerations := v1helper.GetMatchingTolerations(taints, tolerations)if !allTolerated {klog.V(2).Infof("Not all taints are tolerated after update for Pod %v on %v", podNamespacedName.String(), nodeName)// We"re canceling scheduled work (if any), as we"re going to delete the Pod right away.tc.cancelWorkWithEvent(podNamespacedName)tc.taintEvictionQueue.AddWork(NewWorkArgs(podNamespacedName.Name, podNamespacedName.Namespace), time.Now(), time.Now())return}minTolerationTime := getMinTolerationTime(usedTolerations)// getMinTolerationTime returns negative value to denote infinite toleration.if minTolerationTime < 0 {klog.V(4).Infof("New tolerations for %v tolerate forever. Scheduled deletion won"t be cancelled if already scheduled.", podNamespacedName.String())return}startTime := nowtriggerTime := startTime.Add(minTolerationTime)scheduledEviction := tc.taintEvictionQueue.GetWorkerUnsafe(podNamespacedName.String())if scheduledEviction != nil {startTime = scheduledEviction.CreatedAtif startTime.Add(minTolerationTime).Before(triggerTime) {return}tc.cancelWorkWithEvent(podNamespacedName)}tc.taintEvictionQueue.AddWork(NewWorkArgs(podNamespacedName.Name, podNamespacedName.Namespace), startTime, triggerTime)}

tc.handlePodUpdate方法最终也是调用了tc.processPodOnNode对pod做进一步处理；

tc.processPodOnNode方法在上面已经分析过了，这里不再进行分析；

主要逻辑：（1）从informer本地缓存中获取pod对象；（2）获取pod的node name，如果为空，直接return；（3）根据node name从tc.taintedNodes中获取node的污点，如果污点为空，直接return；（4）调用tc.processPodOnNode对pod做进一步处理；

// pkg/controller/nodelifecycle/scheduler/taint_manager.gofunc (tc *NoExecuteTaintManager) handlePodUpdate(podUpdate podUpdateItem) {pod, err := tc.getPod(podUpdate.podName, podUpdate.podNamespace)if err != nil {if apierrors.IsNotFound(err) {// DeletepodNamespacedName := types.NamespacedName{Namespace: podUpdate.podNamespace, Name: podUpdate.podName}klog.V(4).Infof("Noticed pod deletion: %#v", podNamespacedName)tc.cancelWorkWithEvent(podNamespacedName)return}utilruntime.HandleError(fmt.Errorf("could not get pod %s/%s: %v", podUpdate.podName, podUpdate.podNamespace, err))return}// We key the workqueue and shard workers by nodeName. If we don"t match the current state we should not be the one processing the current object.if pod.Spec.NodeName != podUpdate.nodeName {return}// Create or UpdatepodNamespacedName := types.NamespacedName{Namespace: pod.Namespace, Name: pod.Name}klog.V(4).Infof("Noticed pod update: %#v", podNamespacedName)nodeName := pod.Spec.NodeNameif nodeName == "" {return}taints, ok := func() ([]v1.Taint, bool) {tc.taintedNodesLock.Lock()defer tc.taintedNodesLock.Unlock()taints, ok := tc.taintedNodes[nodeName]return taints, ok}()// It"s possible that Node was deleted, or Taints were removed before, which triggered// eviction cancelling if it was needed.if !ok {return}tc.processPodOnNode(podNamespacedName, nodeName, pod.Spec.Tolerations, taints, time.Now())}

taintManager的主要功能为：当某个node被打上NoExecute污点后，其上面的pod如果不能容忍该污点，则taintManager将会驱逐这些pod，而新建的pod也需要容忍该污点才能调度到该node上；

通过kcm启动参数--enable-taint-manager来确定是否启动taintManager，true时启动（启动参数默认值为true）；

kcm启动参数--feature-gates=TaintBasedEvictions=xxx，默认值true，配合--enable-taint-manager共同作用，两者均为true，才会开启污点驱逐；

当node出现NoExecute污点时，判断node上的pod是否能容忍node的污点，不能容忍的pod，会被立即删除，能容忍所有污点的pod，则等待所有污点的容忍时间里最小值后，pod被删除；

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