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；

kcm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；

1.结构体分析

1.1 NoExecuteTaintManager结构体分析

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.go
type NoExecuteTaintManager struct {
    client                clientset.Interface
    recorder              record.EventRecorder
    getPod                GetPodFunc
    getNode               GetNodeFunc
    getPodsAssignedToNode GetPodsByNodeNameFunc

    taintEvictionQueue *TimedWorkerQueue
    // keeps a map from nodeName to all noExecute taints on that Node
    taintedNodesLock sync.Mutex
    taintedNodes     map[string][]v1.Taint

    nodeUpdateChannels []chan nodeUpdateItem
    podUpdateChannels  []chan podUpdateItem

    nodeUpdateQueue workqueue.Interface
    podUpdateQueue  workqueue.Interface
}

1.2 taintEvictionQueue分析

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；

1.3 pod.Spec.Tolerations分析

pod.Spec.Tolerations配置的是pod的污点容忍信息；

// vendor/k8s.io/api/core/v1/types.go
type 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）；

2.初始化分析

2.1 NewNodeLifecycleController

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.go
func 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
            }),
        })
    }
    ...
}

2.1.1 tc.NodeUpdated

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.go
func (tc *NoExecuteTaintManager) NodeUpdated(oldNode *v1.Node, newNode *v1.Node) {
    nodeName := ""
    oldTaints := []v1.Taint{}
    if oldNode != nil {
        nodeName = oldNode.Name
        oldTaints = getNoExecuteTaints(oldNode.Spec.Taints)
    }

    newTaints := []v1.Taint{}
    if newNode != nil {
        nodeName = newNode.Name
        newTaints = getNoExecuteTaints(newNode.Spec.Taints)
    }

    if oldNode != nil && newNode != nil && helper.Semantic.DeepEqual(oldTaints, newTaints) {
        return
    }
    updateItem := nodeUpdateItem{
        nodeName: nodeName,
    }

    tc.nodeUpdateQueue.Add(updateItem)
}

2.1.2 tc.PodUpdated

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.go
func (tc *NoExecuteTaintManager) PodUpdated(oldPod *v1.Pod, newPod *v1.Pod) {
    podName := ""
    podNamespace := ""
    nodeName := ""
    oldTolerations := []v1.Toleration{}
    if oldPod != nil {
        podName = oldPod.Name
        podNamespace = oldPod.Namespace
        nodeName = oldPod.Spec.NodeName
        oldTolerations = oldPod.Spec.Tolerations
    }
    newTolerations := []v1.Toleration{}
    if newPod != nil {
        podName = newPod.Name
        podNamespace = newPod.Namespace
        nodeName = newPod.Spec.NodeName
        newTolerations = 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)
}

2.2 taintEvictionQueue

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.go
func 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.go
func CreateWorkerQueue(f func(args *WorkArgs) error) *TimedWorkerQueue {
    return &TimedWorkerQueue{
        workers:  make(map[string]*TimedWorker),
        workFunc: f,
    }
}

2.2.1 deletePodHandler

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.go
func deletePodHandler(c clientset.Interface, emitEventFunc func(types.NamespacedName)) func(args *WorkArgs) error {
    return func(args *WorkArgs) error {
        ns := args.NamespacedName.Namespace
        name := args.NamespacedName.Name
        klog.V(0).Infof("NoExecuteTaintManager is deleting Pod: %v", args.NamespacedName.String())
        if emitEventFunc != nil {
            emitEventFunc(args.NamespacedName)
        }
        var err error
        for 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
    }
}

2.2.2 tc.taintEvictionQueue.AddWork

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.go
func (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.go
func 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,
    }
}

2.2.3 tc.taintEvictionQueue.Cancel

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.go
func (w *TimedWorker) Cancel() {
    if w != nil {
        w.Timer.Stop()
    }
}

3.核心处理逻辑分析

nc.taintManager.Run

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.go
func (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)
                return
            case 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)
                return
            case 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

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.go
func (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:
            return
        case 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)
        }
    }
}

3.1 tc.handleNodeUpdate

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.go
func (tc *NoExecuteTaintManager) handleNodeUpdate(nodeUpdate nodeUpdateItem) {
    node, err := tc.getNode(nodeUpdate.nodeName)
    if err != nil {
        if apierrors.IsNotFound(err) {
            // Delete
            klog.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 Update
    klog.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)
    }
}

3.1.1 tc.processPodOnNode

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.go
func (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 := now
    triggerTime := startTime.Add(minTolerationTime)
    scheduledEviction := tc.taintEvictionQueue.GetWorkerUnsafe(podNamespacedName.String())
    if scheduledEviction != nil {
        startTime = scheduledEviction.CreatedAt
        if startTime.Add(minTolerationTime).Before(triggerTime) {
            return
        }
        tc.cancelWorkWithEvent(podNamespacedName)
    }
    tc.taintEvictionQueue.AddWork(NewWorkArgs(podNamespacedName.Name, podNamespacedName.Namespace), startTime, triggerTime)
}

3.2 tc.handlePodUpdate

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.go
func (tc *NoExecuteTaintManager) handlePodUpdate(podUpdate podUpdateItem) {
    pod, err := tc.getPod(podUpdate.podName, podUpdate.podNamespace)
    if err != nil {
        if apierrors.IsNotFound(err) {
            // Delete
            podNamespacedName := 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 Update
    podNamespacedName := types.NamespacedName{Namespace: pod.Namespace, Name: pod.Name}
    klog.V(4).Infof("Noticed pod update: %#v", podNamespacedName)
    nodeName := pod.Spec.NodeName
    if 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；

kcm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；