LeaderElection 深度分析（上篇）--- 模块定位、结构、LeaderElector 核心逻辑
基于
client-go v0.36.1tools/leaderelection/源码的超深度、逐行、专业级分析源文件：leaderelection.go (561行) + leasecandidate.go (220行) + healthzadaptor.go (69行) + metrics.go (119行) + resourcelock/interface.go (179行) + resourcelock/leaselock.go (181行) + resourcelock/multilock.go (111行)
一、模块定位
1.1 业务职责与功能定位
LeaderElection 实现了 Kubernetes 中多副本控制器实例的领导者选举机制。在多副本部署场景下，同一控制器（如 kube-controller-manager）有多个实例同时运行，但只有一个实例应该执行实际调谐工作，避免重复操作。LeaderElection 通过 Lease 资源的竞争获取来决定谁是领导者。
核心职责：
| 职责 | 描述 |
|---|---|
| 竞争选举 | 多个候选者通过 Lease 资源的 Get/Create/Update 竞争领导者 |
| 租约续约 | 领导者持续续约 Lease，证明自己仍然存活 |
| 租约过期 | 非领导者检测到租约过期后尝试接管 |
| 优雅释放 | 主动释放租约（ReleaseOnCancel），避免僵尸领导者 |
| 健康检查 | HealthzAdaptor 将选举状态暴露给 /healthz 端点 |
| 协调选举 | ALPHA: 基于 LeaseCandidate 的协调选举（支持优雅切换） |
| 锁迁移 | MultiLock 支持从旧锁类型迁移到新锁类型 |
LeaderElection 解决的核心问题：如何保证多副本控制器只有一个在执行关键路径？
1.2 在系统中的位置
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LeaderElection (本次分析)
Kubernetes 控制面
Leader
Standby
Standby
kube-controller-manager #1
kube-controller-manager #2
kube-controller-manager #3
LeaderElector
LeaseLock
(resourcelock)
MultiLock
(迁移用)
HealthzAdaptor
LeaseCandidate
(ALPHA)
Metrics
Lease CRD
coordination.k8s.io
LeaseCandidate CRD
coordination.k8s.io (v1beta1)
1.3 数据流入流出
输入：
- 多个候选者通过
Lock.Get/Create/Update竞争 Lease 资源 - LeaseCandidate 的 Informer 事件（PingTime 触发续约）
- 健康检查请求 (
/healthz)
输出：
OnStartedLeading(ctx)--- 成为领导者时回调OnStoppedLeading()--- 失去领导权时回调OnNewLeader(identity)--- 观察到新领导者时回调- Lease 资源的更新（续约/获取/释放）
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LeaderElection
输入
Lock.Get()
Lock.Create()
Lock.Update()
LeaseCandidate PingTime
HTTP /healthz
acquire()
renew()
Check()
Callbacks
OnStartedLeading(ctx)
OnStoppedLeading()
OnNewLeader(identity)
Lease 资源更新
1.4 选举时间参数关系
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约束关系
时间参数 (默认值)
LeaseDuration = 15s
租约有效期
RenewDeadline = 10s
续约截止时间
RetryPeriod = 2s
重试间隔
LeaseDuration > RenewDeadline
(15 > 10) ✓
RenewDeadline > RetryPeriod × JitterFactor
(10 > 2×1.2=2.4) ✓
非领导者等待 LeaseDuration
后才能尝试接管
领导者在 RenewDeadline 内
必须成功续约一次
每隔 RetryPeriod 尝试一次
(带 1.2x 抖动)
二、模块整体结构
2.1 类结构、接口定义、依赖注入关系
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.lollipop{fill:#ECECFF!important;stroke:#333333!important;stroke-width:1;}#mermaid-svg-CV4EZc1oyNh5PcIF .edgeTerminals{font-size:11px;line-height:initial;}#mermaid-svg-CV4EZc1oyNh5PcIF .classTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-CV4EZc1oyNh5PcIF .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-CV4EZc1oyNh5PcIF .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-CV4EZc1oyNh5PcIF :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} uses
contains
depends on
optional
tracks
references
implements
implements
wraps two
contains
optional (Coordinated)
LeaderElector
-config LeaderElectionConfig
-observedRecord LeaderElectionRecord
-observedRawRecord \[\]byte
-observedTime time.Time
-reportedLeader string
-clock clock.Clock
-observedRecordLock sync.RWMutex
-metrics leaderMetricsAdapter
+Run(ctx)
+acquire(ctx) : bool
+renew(ctx)
+tryAcquireOrRenew(ctx) : bool
+tryCoordinatedRenew(ctx) : bool
+release(logger) : bool
+IsLeader() : bool
+GetLeader() : string
+Check(maxTolerableExpiredLease) : error
-maybeReportTransition()
-isLeaseValid(now) : bool
-setObservedRecord(record)
-getObservedRecord() : LeaderElectionRecord
LeaderElectionConfig
+Lock rl.Interface
+LeaseDuration time.Duration
+RenewDeadline time.Duration
+RetryPeriod time.Duration
+Callbacks LeaderCallbacks
+WatchDog *HealthzAdaptor
+ReleaseOnCancel bool
+Name string
+Coordinated bool
LeaderCallbacks
+OnStartedLeading func(ctx)
+OnStoppedLeading func()
+OnNewLeader func(identity)
LeaderElectionRecord
+HolderIdentity string
+LeaseDurationSeconds int
+AcquireTime metav1.Time
+RenewTime metav1.Time
+LeaderTransitions int
+Strategy v1.CoordinatedLeaseStrategy
+PreferredHolder string
HealthzAdaptor
-pointerLock sync.Mutex
-le *LeaderElector
-timeout time.Duration
+Name() : string
+Check(req) : error
+SetLeaderElection(le)
LeaseCandidate
-leaseClient LeaseCandidateInterface
-leaseCandidateInformer SharedIndexInformer
-leaseCandidateLister LeaseCandidateLister
-informerFactory SharedInformerFactory
-hasSynced InformerSynced
-queue TypedRateLimitingInterface
-name string
-namespace string
-leaseName string
-clock clock.Clock
-binaryVersion string
-emulationVersion string
-strategy v1.CoordinatedLeaseStrategy
+Run(ctx)
-runWorker(ctx)
-processNextWorkItem(ctx) : bool
-ensureLease(ctx) : error
-enqueueLease()
-newLeaseCandidate() : *v1beta1.LeaseCandidate
<<interface>>
rl_Interface
+Get(ctx)(*LeaderElectionRecord, \[\]byte, error)
+Create(ctx, ler) : error
+Update(ctx, ler) : error
+RecordEvent(string)
+Identity() : string
+Describe() : string
LeaseLock
+LeaseMeta metav1.ObjectMeta
+Client LeasesGetter
+LockConfig ResourceLockConfig
-lease *coordinationv1.Lease
+Labels map<string>string
+Get(ctx)(*LeaderElectionRecord, \[\]byte, error)
+Create(ctx, ler) : error
+Update(ctx, ler) : error
+RecordEvent(string)
+Describe() : string
+Identity() : string
MultiLock
+Primary Interface
+Secondary Interface
+Get(ctx)(*LeaderElectionRecord, \[\]byte, error)
+Create(ctx, ler) : error
+Update(ctx, ler) : error
+RecordEvent(string)
+Describe() : string
+Identity() : string
ResourceLockConfig
+Identity string
+EventRecorder EventRecorder
2.2 核心方法清单与作用
LeaderElector 方法
| 方法 | 作用 | 阻塞 |
|---|---|---|
Run(ctx) |
主循环：acquire + renew | ✅ 直到 ctx 取消或失去租约 |
acquire(ctx) |
竞争获取领导权 | ✅ 直到成功或 ctx 取消 |
renew(ctx) |
持续续约 | ✅ 直到续约失败或 ctx 取消 |
tryAcquireOrRenew(ctx) |
单次尝试获取/续约 | ❌ |
tryCoordinatedRenew(ctx) |
协调模式下的续约 | ❌ |
release(logger) |
主动释放租约 | ❌ |
IsLeader() |
当前是否是领导者 | ❌ |
GetLeader() |
获取当前领导者 ID | ❌ |
Check(timeout) |
健康检查 | ❌ |
maybeReportTransition() |
报告领导权转移 | ❌ |
LeaseLock 方法
| 方法 | 作用 |
|---|---|
Get(ctx) |
获取 Lease → 转换为 LeaderElectionRecord |
Create(ctx, ler) |
创建 Lease |
Update(ctx, ler) |
更新 Lease |
RecordEvent(s) |
记录事件 |
Identity() |
返回锁持有者 ID |
Describe() |
返回 ns/name 描述 |
LeaseCandidate 方法
| 方法 | 作用 |
|---|---|
Run(ctx) |
启动候选者控制器 |
ensureLease(ctx) |
创建/续约 LeaseCandidate |
enqueueLease() |
将工作项入队 |
2.3 内部调用关系
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LeaseLock
Lock (Interface)
Callbacks
LeaderElector
Run(ctx)
acquire(ctx)
renew(ctx)
tryAcquireOrRenew(ctx)
tryCoordinatedRenew(ctx)
release(logger)
maybeReportTransition()
isLeaseValid(now)
setObservedRecord()
getObservedRecord()
Check(timeout)
OnStartedLeading(ctx)
OnStoppedLeading()
OnNewLeader(identity)
Lock.Get()
Lock.Create()
Lock.Update()
LeaseLock.Get()
LeaseLock.Create()
LeaseLock.Update()
LeaseSpecToLeaderElectionRecord()
LeaderElectionRecordToLeaseSpec()
HealthzAdaptor.Check()
SetLeaderElection()
三、核心业务逻辑深度解析 --- LeaderElector
3.1 NewLeaderElector --- 构造函数
go
func NewLeaderElector(lec LeaderElectionConfig) (*LeaderElector, error) {
// ─── 参数校验 ───
// 约束1: LeaseDuration 必须大于 RenewDeadline
// 语义：租约有效期必须长于续约截止时间
// 否则：领导者还没来得及续约，租约就过期了
if lec.LeaseDuration <= lec.RenewDeadline {
return nil, fmt.Errorf("leaseDuration must be greater than renewDeadline")
}
// 约束2: RenewDeadline 必须大于 RetryPeriod × JitterFactor
// JitterFactor = 1.2，即 2s × 1.2 = 2.4s
// 语义：续约截止时间内至少能完成一次重试（考虑抖动）
// 否则：可能还没重试一次就超时了
if lec.RenewDeadline <= time.Duration(JitterFactor*float64(lec.RetryPeriod)) {
return nil, fmt.Errorf("renewDeadline must be greater than retryPeriod*JitterFactor")
}
// 约束3-5: 三个时间参数都必须大于 0
if lec.LeaseDuration < 1 {
return nil, fmt.Errorf("leaseDuration must be greater than zero")
}
if lec.RenewDeadline < 1 {
return nil, fmt.Errorf("renewDeadline must be greater than zero")
}
if lec.RetryPeriod < 1 {
return nil, fmt.Errorf("retryPeriod must be greater than zero")
}
// 约束6-7: 必须的回调函数
if lec.Callbacks.OnStartedLeading == nil {
return nil, fmt.Errorf("OnStartedLeading callback must not be nil")
}
if lec.Callbacks.OnStoppedLeading == nil {
return nil, fmt.Errorf("OnStoppedLeading callback must not be nil")
}
// OnNewLeader 可以为 nil（可选回调）
// 约束8: Lock 不能为空
if lec.Lock == nil {
return nil, fmt.Errorf("Lock must not be nil.")
}
// 约束9: Lock Identity 不能为空
id := lec.Lock.Identity()
if id == "" {
return nil, fmt.Errorf("Lock identity is empty")
}
// ─── 构造 LeaderElector ───
le := LeaderElector{
config: lec,
clock: clock.RealClock{}, // 使用真实时钟
metrics: globalMetricsFactory.newLeaderMetrics(), // 全局指标工厂
}
le.metrics.leaderOff(le.config.Name) // 初始状态：不是领导者
return &le, nil
}参数校验决策树：
#mermaid-svg-M4E9amvvRWJenOMN{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-M4E9amvvRWJenOMN .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-M4E9amvvRWJenOMN .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-M4E9amvvRWJenOMN .error-icon{fill:#552222;}#mermaid-svg-M4E9amvvRWJenOMN .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-M4E9amvvRWJenOMN .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-M4E9amvvRWJenOMN .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-M4E9amvvRWJenOMN .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-M4E9amvvRWJenOMN .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-M4E9amvvRWJenOMN .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-M4E9amvvRWJenOMN .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-M4E9amvvRWJenOMN .marker{fill:#333333;stroke:#333333;}#mermaid-svg-M4E9amvvRWJenOMN .marker.cross{stroke:#333333;}#mermaid-svg-M4E9amvvRWJenOMN svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-M4E9amvvRWJenOMN p{margin:0;}#mermaid-svg-M4E9amvvRWJenOMN .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-M4E9amvvRWJenOMN .cluster-label text{fill:#333;}#mermaid-svg-M4E9amvvRWJenOMN .cluster-label span{color:#333;}#mermaid-svg-M4E9amvvRWJenOMN .cluster-label span p{background-color:transparent;}#mermaid-svg-M4E9amvvRWJenOMN .label text,#mermaid-svg-M4E9amvvRWJenOMN span{fill:#333;color:#333;}#mermaid-svg-M4E9amvvRWJenOMN .node rect,#mermaid-svg-M4E9amvvRWJenOMN .node circle,#mermaid-svg-M4E9amvvRWJenOMN .node ellipse,#mermaid-svg-M4E9amvvRWJenOMN .node polygon,#mermaid-svg-M4E9amvvRWJenOMN .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-M4E9amvvRWJenOMN .rough-node .label text,#mermaid-svg-M4E9amvvRWJenOMN .node .label text,#mermaid-svg-M4E9amvvRWJenOMN .image-shape .label,#mermaid-svg-M4E9amvvRWJenOMN .icon-shape .label{text-anchor:middle;}#mermaid-svg-M4E9amvvRWJenOMN .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-M4E9amvvRWJenOMN .rough-node .label,#mermaid-svg-M4E9amvvRWJenOMN .node .label,#mermaid-svg-M4E9amvvRWJenOMN .image-shape .label,#mermaid-svg-M4E9amvvRWJenOMN .icon-shape .label{text-align:center;}#mermaid-svg-M4E9amvvRWJenOMN .node.clickable{cursor:pointer;}#mermaid-svg-M4E9amvvRWJenOMN .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-M4E9amvvRWJenOMN .arrowheadPath{fill:#333333;}#mermaid-svg-M4E9amvvRWJenOMN .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-M4E9amvvRWJenOMN .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-M4E9amvvRWJenOMN .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-M4E9amvvRWJenOMN .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-M4E9amvvRWJenOMN .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-M4E9amvvRWJenOMN .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-M4E9amvvRWJenOMN .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-M4E9amvvRWJenOMN .cluster text{fill:#333;}#mermaid-svg-M4E9amvvRWJenOMN .cluster span{color:#333;}#mermaid-svg-M4E9amvvRWJenOMN div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-M4E9amvvRWJenOMN .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-M4E9amvvRWJenOMN rect.text{fill:none;stroke-width:0;}#mermaid-svg-M4E9amvvRWJenOMN .icon-shape,#mermaid-svg-M4E9amvvRWJenOMN .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-M4E9amvvRWJenOMN .icon-shape p,#mermaid-svg-M4E9amvvRWJenOMN .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-M4E9amvvRWJenOMN .icon-shape .label rect,#mermaid-svg-M4E9amvvRWJenOMN .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-M4E9amvvRWJenOMN .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-M4E9amvvRWJenOMN .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-M4E9amvvRWJenOMN :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} No
Yes
No
Yes
No
No
No
No
No
No
No
Yes
NewLeaderElector(config)
LeaseDuration > RenewDeadline?
RenewDeadline > RetryPeriod × 1.2?
LeaseDuration > 0?
RenewDeadline > 0?
RetryPeriod > 0?
OnStartedLeading ≠ nil?
OnStoppedLeading ≠ nil?
Lock ≠ nil?
Lock.Identity() ≠ ''?
return &LeaderElector, nil
error: leaseDuration must be greater than renewDeadline
error: renewDeadline must be greater than retryPeriod*JitterFactor
error: xxx must be greater than zero
error: OnStartedLeading callback must not be nil
error: OnStoppedLeading callback must not be nil
error: Lock must not be nil
error: Lock identity is empty
3.2 Run --- 主循环
go
func (le *LeaderElector) Run(ctx context.Context) {
// ─── 步骤1: defer 链（LIFO 执行顺序） ───
// 最后执行：panic 恢复
defer runtime.HandleCrashWithContext(ctx)
// 倒数第二执行：OnStoppedLeading 回调
// 注意：无论是否曾成为领导者，OnStoppedLeading 都会被调用
// 这是故意的设计：即使从未成为领导者，退出时也需要清理
defer le.config.Callbacks.OnStoppedLeading()
// ─── 步骤2: 竞争获取领导权 ───
if !le.acquire(ctx) {
return // ctx 被取消 → 退出
// 注意：此时 OnStoppedLeading 已经通过 defer 被调度
}
// ─── 步骤3: 成为领导者 ───
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// 异步启动用户的领导者逻辑
// 用户的 OnStartedLeading 收到一个 ctx，
// 当失去领导权时这个 ctx 会被 cancel
go le.config.Callbacks.OnStartedLeading(ctx)
// ─── 步骤4: 持续续约 ───
le.renew(ctx)
// renew 返回意味着失去了领导权
// 此时 ctx 被 cancel → 用户的 OnStartedLeading 逻辑应该退出
}Run 的完整生命周期：
#mermaid-svg-Xc4wdUGuRBFs5Abe{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-Xc4wdUGuRBFs5Abe .error-icon{fill:#552222;}#mermaid-svg-Xc4wdUGuRBFs5Abe .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-Xc4wdUGuRBFs5Abe .marker{fill:#333333;stroke:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .marker.cross{stroke:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-Xc4wdUGuRBFs5Abe p{margin:0;}#mermaid-svg-Xc4wdUGuRBFs5Abe defs #statediagram-barbEnd{fill:#333333;stroke:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe g.stateGroup text{fill:#9370DB;stroke:none;font-size:10px;}#mermaid-svg-Xc4wdUGuRBFs5Abe g.stateGroup text{fill:#333;stroke:none;font-size:10px;}#mermaid-svg-Xc4wdUGuRBFs5Abe g.stateGroup .state-title{font-weight:bolder;fill:#131300;}#mermaid-svg-Xc4wdUGuRBFs5Abe g.stateGroup rect{fill:#ECECFF;stroke:#9370DB;}#mermaid-svg-Xc4wdUGuRBFs5Abe g.stateGroup line{stroke:#333333;stroke-width:1;}#mermaid-svg-Xc4wdUGuRBFs5Abe .transition{stroke:#333333;stroke-width:1;fill:none;}#mermaid-svg-Xc4wdUGuRBFs5Abe .stateGroup .composit{fill:white;border-bottom:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .stateGroup .alt-composit{fill:#e0e0e0;border-bottom:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .state-note{stroke:#aaaa33;fill:#fff5ad;}#mermaid-svg-Xc4wdUGuRBFs5Abe .state-note text{fill:black;stroke:none;font-size:10px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .stateLabel .box{stroke:none;stroke-width:0;fill:#ECECFF;opacity:0.5;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edgeLabel .label rect{fill:#ECECFF;opacity:0.5;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-Xc4wdUGuRBFs5Abe .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-Xc4wdUGuRBFs5Abe .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-Xc4wdUGuRBFs5Abe .edgeLabel .label text{fill:#333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .label div .edgeLabel{color:#333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .stateLabel text{fill:#131300;font-size:10px;font-weight:bold;}#mermaid-svg-Xc4wdUGuRBFs5Abe .node circle.state-start{fill:#333333;stroke:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .node .fork-join{fill:#333333;stroke:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .node circle.state-end{fill:#9370DB;stroke:white;stroke-width:1.5;}#mermaid-svg-Xc4wdUGuRBFs5Abe .end-state-inner{fill:white;stroke-width:1.5;}#mermaid-svg-Xc4wdUGuRBFs5Abe .node rect{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .node polygon{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe #statediagram-barbEnd{fill:#333333;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-cluster rect{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .cluster-label,#mermaid-svg-Xc4wdUGuRBFs5Abe .nodeLabel{color:#131300;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-cluster rect.outer{rx:5px;ry:5px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-state .divider{stroke:#9370DB;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-state .title-state{rx:5px;ry:5px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-cluster.statediagram-cluster .inner{fill:white;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-cluster.statediagram-cluster-alt .inner{fill:#f0f0f0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-cluster .inner{rx:0;ry:0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-state rect.basic{rx:5px;ry:5px;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-state rect.divider{stroke-dasharray:10,10;fill:#f0f0f0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .note-edge{stroke-dasharray:5;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-note rect{fill:#fff5ad;stroke:#aaaa33;stroke-width:1px;rx:0;ry:0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-note rect{fill:#fff5ad;stroke:#aaaa33;stroke-width:1px;rx:0;ry:0;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-note text{fill:black;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram-note .nodeLabel{color:black;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagram .edgeLabel{color:red;}#mermaid-svg-Xc4wdUGuRBFs5Abe #dependencyStart,#mermaid-svg-Xc4wdUGuRBFs5Abe #dependencyEnd{fill:#333333;stroke:#333333;stroke-width:1;}#mermaid-svg-Xc4wdUGuRBFs5Abe .statediagramTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-Xc4wdUGuRBFs5Abe :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} Run()
acquire() succeeds
ctx cancelled during acquire
OnStartedLeading(ctx) goroutine
renew fails
ctx cancelled during renew
ReleaseOnCancel=true
ReleaseOnCancel=false
release() done
defer OnStoppedLeading()
Acquiring
Leading
Stopped
Renewing
LostLease
Releasing
Lock (Lease) OnStartedLeading renew() acquire() LeaderElector Context Lock (Lease) OnStartedLeading renew() acquire() LeaderElector Context #mermaid-svg-NL1aJmAphjcm3vNw{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-NL1aJmAphjcm3vNw .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-NL1aJmAphjcm3vNw .error-icon{fill:#552222;}#mermaid-svg-NL1aJmAphjcm3vNw .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-NL1aJmAphjcm3vNw .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-NL1aJmAphjcm3vNw .marker{fill:#333333;stroke:#333333;}#mermaid-svg-NL1aJmAphjcm3vNw .marker.cross{stroke:#333333;}#mermaid-svg-NL1aJmAphjcm3vNw svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-NL1aJmAphjcm3vNw p{margin:0;}#mermaid-svg-NL1aJmAphjcm3vNw .actor{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-NL1aJmAphjcm3vNw text.actor>tspan{fill:black;stroke:none;}#mermaid-svg-NL1aJmAphjcm3vNw .actor-line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-NL1aJmAphjcm3vNw .innerArc{stroke-width:1.5;stroke-dasharray:none;}#mermaid-svg-NL1aJmAphjcm3vNw .messageLine0{stroke-width:1.5;stroke-dasharray:none;stroke:#333;}#mermaid-svg-NL1aJmAphjcm3vNw .messageLine1{stroke-width:1.5;stroke-dasharray:2,2;stroke:#333;}#mermaid-svg-NL1aJmAphjcm3vNw #arrowhead path{fill:#333;stroke:#333;}#mermaid-svg-NL1aJmAphjcm3vNw .sequenceNumber{fill:white;}#mermaid-svg-NL1aJmAphjcm3vNw #sequencenumber{fill:#333;}#mermaid-svg-NL1aJmAphjcm3vNw #crosshead path{fill:#333;stroke:#333;}#mermaid-svg-NL1aJmAphjcm3vNw .messageText{fill:#333;stroke:none;}#mermaid-svg-NL1aJmAphjcm3vNw .labelBox{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-NL1aJmAphjcm3vNw .labelText,#mermaid-svg-NL1aJmAphjcm3vNw .labelText>tspan{fill:black;stroke:none;}#mermaid-svg-NL1aJmAphjcm3vNw .loopText,#mermaid-svg-NL1aJmAphjcm3vNw .loopText>tspan{fill:black;stroke:none;}#mermaid-svg-NL1aJmAphjcm3vNw .loopLine{stroke-width:2px;stroke-dasharray:2,2;stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-NL1aJmAphjcm3vNw .note{stroke:#aaaa33;fill:#fff5ad;}#mermaid-svg-NL1aJmAphjcm3vNw .noteText,#mermaid-svg-NL1aJmAphjcm3vNw .noteText>tspan{fill:black;stroke:none;}#mermaid-svg-NL1aJmAphjcm3vNw .activation0{fill:#f4f4f4;stroke:#666;}#mermaid-svg-NL1aJmAphjcm3vNw .activation1{fill:#f4f4f4;stroke:#666;}#mermaid-svg-NL1aJmAphjcm3vNw .activation2{fill:#f4f4f4;stroke:#666;}#mermaid-svg-NL1aJmAphjcm3vNw .actorPopupMenu{position:absolute;}#mermaid-svg-NL1aJmAphjcm3vNw .actorPopupMenuPanel{position:absolute;fill:#ECECFF;box-shadow:0px 8px 16px 0px rgba(0,0,0,0.2);filter:drop-shadow(3px 5px 2px rgb(0 0 0 / 0.4));}#mermaid-svg-NL1aJmAphjcm3vNw .actor-man line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-NL1aJmAphjcm3vNw .actor-man circle,#mermaid-svg-NL1aJmAphjcm3vNw line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;stroke-width:2px;}#mermaid-svg-NL1aJmAphjcm3vNw :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} loop每 RetryPeriod (带抖动) 用户开始执行领导者逻辑 loop在 RenewDeadline 内重试 继续循环 ctx 被取消 → 应退出 alt续约成功续约失败 loop每 RetryPeriod Run(ctx)acquire(ctx)tryAcquireOrRenew()true/falseacquired = truego OnStartedLeading(ctx)renew(ctx)PollUntilContextTimeout(RetryPeriod, RenewDeadline)tryAcquireOrRenew()true/false失去领导权cancel()defer OnStoppedLeading()
3.3 acquire --- 竞争获取领导权
go
func (le *LeaderElector) acquire(ctx context.Context) bool {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
succeeded := false
desc := le.config.Lock.Describe()
logger := klog.FromContext(ctx)
logger.Info("Attempting to acquire leader lease...", "lock", desc)
// JitterUntilWithContext: 以 RetryPeriod 为间隔，带 JitterFactor=1.2 抖动
// 第4个参数 true = sliding（从函数返回后开始计时）
wait.JitterUntilWithContext(ctx, func(ctx context.Context) {
if !le.config.Coordinated {
// 标准模式：tryAcquireOrRenew
succeeded = le.tryAcquireOrRenew(ctx)
} else {
// 协调模式：tryCoordinatedRenew
succeeded = le.tryCoordinatedRenew(ctx)
}
le.maybeReportTransition()
if !succeeded {
logger.V(4).Info("Failed to acquire lease", "lock", desc)
return
// 失败 → 等待下次重试
}
// 成功 → 记录事件 + 更新指标 + 取消上下文退出循环
le.config.Lock.RecordEvent("became leader")
le.metrics.leaderOn(le.config.Name)
logger.Info("Successfully acquired lease", "lock", desc)
cancel()
// cancel() → JitterUntilWithContext 检测到 ctx.Done() → 退出
}, le.config.RetryPeriod, JitterFactor, true)
return succeeded
// ctx 取消 → succeeded=false → Run 退出
// acquire 成功 → succeeded=true → Run 继续到 renew
}acquire 流程：
#mermaid-svg-Q142BvNkJZB8Gjah{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-Q142BvNkJZB8Gjah .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-Q142BvNkJZB8Gjah .error-icon{fill:#552222;}#mermaid-svg-Q142BvNkJZB8Gjah .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-Q142BvNkJZB8Gjah .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-Q142BvNkJZB8Gjah .marker{fill:#333333;stroke:#333333;}#mermaid-svg-Q142BvNkJZB8Gjah .marker.cross{stroke:#333333;}#mermaid-svg-Q142BvNkJZB8Gjah svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-Q142BvNkJZB8Gjah p{margin:0;}#mermaid-svg-Q142BvNkJZB8Gjah .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-Q142BvNkJZB8Gjah .cluster-label text{fill:#333;}#mermaid-svg-Q142BvNkJZB8Gjah .cluster-label span{color:#333;}#mermaid-svg-Q142BvNkJZB8Gjah .cluster-label span p{background-color:transparent;}#mermaid-svg-Q142BvNkJZB8Gjah .label text,#mermaid-svg-Q142BvNkJZB8Gjah span{fill:#333;color:#333;}#mermaid-svg-Q142BvNkJZB8Gjah .node rect,#mermaid-svg-Q142BvNkJZB8Gjah .node circle,#mermaid-svg-Q142BvNkJZB8Gjah .node ellipse,#mermaid-svg-Q142BvNkJZB8Gjah .node polygon,#mermaid-svg-Q142BvNkJZB8Gjah .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-Q142BvNkJZB8Gjah .rough-node .label text,#mermaid-svg-Q142BvNkJZB8Gjah .node .label text,#mermaid-svg-Q142BvNkJZB8Gjah .image-shape .label,#mermaid-svg-Q142BvNkJZB8Gjah .icon-shape .label{text-anchor:middle;}#mermaid-svg-Q142BvNkJZB8Gjah .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-Q142BvNkJZB8Gjah .rough-node .label,#mermaid-svg-Q142BvNkJZB8Gjah .node .label,#mermaid-svg-Q142BvNkJZB8Gjah .image-shape .label,#mermaid-svg-Q142BvNkJZB8Gjah .icon-shape .label{text-align:center;}#mermaid-svg-Q142BvNkJZB8Gjah .node.clickable{cursor:pointer;}#mermaid-svg-Q142BvNkJZB8Gjah .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-Q142BvNkJZB8Gjah .arrowheadPath{fill:#333333;}#mermaid-svg-Q142BvNkJZB8Gjah .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-Q142BvNkJZB8Gjah .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-Q142BvNkJZB8Gjah .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-Q142BvNkJZB8Gjah .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-Q142BvNkJZB8Gjah .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-Q142BvNkJZB8Gjah .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-Q142BvNkJZB8Gjah .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-Q142BvNkJZB8Gjah .cluster text{fill:#333;}#mermaid-svg-Q142BvNkJZB8Gjah .cluster span{color:#333;}#mermaid-svg-Q142BvNkJZB8Gjah div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-Q142BvNkJZB8Gjah .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-Q142BvNkJZB8Gjah rect.text{fill:none;stroke-width:0;}#mermaid-svg-Q142BvNkJZB8Gjah .icon-shape,#mermaid-svg-Q142BvNkJZB8Gjah .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-Q142BvNkJZB8Gjah .icon-shape p,#mermaid-svg-Q142BvNkJZB8Gjah .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-Q142BvNkJZB8Gjah .icon-shape .label rect,#mermaid-svg-Q142BvNkJZB8Gjah .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-Q142BvNkJZB8Gjah .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-Q142BvNkJZB8Gjah .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-Q142BvNkJZB8Gjah :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} No
Yes
No
Yes
acquire(ctx)
succeeded = false
JitterUntilWithContext
(RetryPeriod, JitterFactor=1.2)
Coordinated?
tryAcquireOrRenew(ctx)
tryCoordinatedRenew(ctx)
maybeReportTransition()
succeeded?
V(4): Failed to acquire lease
RecordEvent('became leader')
metrics.leaderOn()
cancel() → 退出循环
return succeeded
3.4 renew --- 持续续约
go
func (le *LeaderElector) renew(ctx context.Context) {
defer le.config.Lock.RecordEvent("stopped leading")
// 无论何时退出 renew，都记录 "stopped leading" 事件
ctx, cancel := context.WithCancel(ctx)
defer cancel()
logger := klog.FromContext(ctx)
// UntilWithContext: 以 RetryPeriod 为间隔无限循环
// 直到 ctx 被取消
wait.UntilWithContext(ctx, func(ctx context.Context) {
// 在每次 RetryPeriod 间隔内，使用 PollUntilContextTimeout 进行续约
// PollUntilContextTimeout:
// - 以 RetryPeriod 为内部重试间隔
// - 以 RenewDeadline 为总体超时
// - immediate=true: 第一次立即执行
err := wait.PollUntilContextTimeout(ctx, le.config.RetryPeriod, le.config.RenewDeadline, true,
func(ctx context.Context) (done bool, err error) {
// 短路：ctx 已取消 → 不执行
if err := ctx.Err(); err != nil {
return false, err
}
if !le.config.Coordinated {
return le.tryAcquireOrRenew(ctx), nil
} else {
return le.tryCoordinatedRenew(ctx), nil
}
},
)
le.maybeReportTransition()
if err == nil {
logger.V(5).Info("Successfully renewed lease", "lock", le.config.Lock.Describe())
return
// 续约成功 → 等待下一个 RetryPeriod 再续约
}
// 续约失败 → 失去领导权
le.metrics.leaderOff(le.config.Name)
logger.Info("Failed to renew lease", "lock", le.config.Lock.Describe(), "err", err)
cancel()
// cancel → UntilWithContext 退出
}, le.config.RetryPeriod)
// ─── 失去领导权后的处理 ───
if le.config.ReleaseOnCancel {
le.release(logger)
// 主动释放租约，将 HolderIdentity 清空
// 避免：领导者已停止但仍持有 Lease → 其他候选者需等 LeaseDuration
}
}renew 的双层循环结构：
#mermaid-svg-CVfNwwSTVa6jcJz2{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-CVfNwwSTVa6jcJz2 .error-icon{fill:#552222;}#mermaid-svg-CVfNwwSTVa6jcJz2 .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-CVfNwwSTVa6jcJz2 .marker{fill:#333333;stroke:#333333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .marker.cross{stroke:#333333;}#mermaid-svg-CVfNwwSTVa6jcJz2 svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-CVfNwwSTVa6jcJz2 p{margin:0;}#mermaid-svg-CVfNwwSTVa6jcJz2 .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster-label text{fill:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster-label span{color:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster-label span p{background-color:transparent;}#mermaid-svg-CVfNwwSTVa6jcJz2 .label text,#mermaid-svg-CVfNwwSTVa6jcJz2 span{fill:#333;color:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .node rect,#mermaid-svg-CVfNwwSTVa6jcJz2 .node circle,#mermaid-svg-CVfNwwSTVa6jcJz2 .node ellipse,#mermaid-svg-CVfNwwSTVa6jcJz2 .node polygon,#mermaid-svg-CVfNwwSTVa6jcJz2 .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .rough-node .label text,#mermaid-svg-CVfNwwSTVa6jcJz2 .node .label text,#mermaid-svg-CVfNwwSTVa6jcJz2 .image-shape .label,#mermaid-svg-CVfNwwSTVa6jcJz2 .icon-shape .label{text-anchor:middle;}#mermaid-svg-CVfNwwSTVa6jcJz2 .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .rough-node .label,#mermaid-svg-CVfNwwSTVa6jcJz2 .node .label,#mermaid-svg-CVfNwwSTVa6jcJz2 .image-shape .label,#mermaid-svg-CVfNwwSTVa6jcJz2 .icon-shape .label{text-align:center;}#mermaid-svg-CVfNwwSTVa6jcJz2 .node.clickable{cursor:pointer;}#mermaid-svg-CVfNwwSTVa6jcJz2 .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .arrowheadPath{fill:#333333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-CVfNwwSTVa6jcJz2 .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-CVfNwwSTVa6jcJz2 .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-CVfNwwSTVa6jcJz2 .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster text{fill:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 .cluster span{color:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-CVfNwwSTVa6jcJz2 .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-CVfNwwSTVa6jcJz2 rect.text{fill:none;stroke-width:0;}#mermaid-svg-CVfNwwSTVa6jcJz2 .icon-shape,#mermaid-svg-CVfNwwSTVa6jcJz2 .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-CVfNwwSTVa6jcJz2 .icon-shape p,#mermaid-svg-CVfNwwSTVa6jcJz2 .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-CVfNwwSTVa6jcJz2 .icon-shape .label rect,#mermaid-svg-CVfNwwSTVa6jcJz2 .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-CVfNwwSTVa6jcJz2 .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-CVfNwwSTVa6jcJz2 .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-CVfNwwSTVa6jcJz2 :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} Yes
No
Yes
No
UntilWithContext
(RetryPeriod 间隔)
PollUntilContextTimeout
(RetryPeriod 间隔, RenewDeadline 超时)
tryAcquireOrRenew()
续约成功?
V(5): renewed
return → 等下次
metrics.leaderOff()
cancel() → 退出
ReleaseOnCancel?
release(logger)
退出
渲染错误: Mermaid 渲染失败: Parse error on line 14: ... POLL-->>LOOP: err=nil → 继续 -----------------------^ Expecting '+', '-', '()', 'ACTOR', got 'loop'
3.5 tryAcquireOrRenew --- 单次获取/续约尝试（核心算法）
go
func (le *LeaderElector) tryAcquireOrRenew(ctx context.Context) bool {
logger := klog.FromContext(ctx)
now := metav1.NewTime(le.clock.Now())
// ─── 构造本地的选举记录 ───
leaderElectionRecord := rl.LeaderElectionRecord{
HolderIdentity: le.config.Lock.Identity(), // 本候选者 ID
LeaseDurationSeconds: int(le.config.LeaseDuration / time.Second),
RenewTime: now, // 续约时间 = 当前时间
AcquireTime: now, // 获取时间 = 当前时间（如果是新获取）
}
// ═══ 步骤1: Fast Path --- 乐观更新 ═══
// 如果当前是领导者且租约有效，直接 Update 而不先 Get
// 这是最常见的路径（领导者大部分时间都在续约）
if le.IsLeader() && le.isLeaseValid(now.Time) {
oldObservedRecord := le.getObservedRecord()
leaderElectionRecord.AcquireTime = oldObservedRecord.AcquireTime
// 保持原始获取时间不变
leaderElectionRecord.LeaderTransitions = oldObservedRecord.LeaderTransitions
// 保持领导权转移次数不变
err := le.config.Lock.Update(ctx, leaderElectionRecord)
if err == nil {
le.setObservedRecord(&leaderElectionRecord)
return true
// Fast Path 成功 → 直接返回
}
// Fast Path 失败（可能是冲突/网络问题）→ 回退到 Slow Path
logger.V(2).Info("Failed to update lease optimistically, falling back to slow path",
"lock", le.config.Lock.Describe(), "err", err)
}
// ═══ 步骤2: Slow Path --- Get 或 Create ═══
oldLeaderElectionRecord, oldLeaderElectionRawRecord, err := le.config.Lock.Get(ctx)
if err != nil {
if !errors.IsNotFound(err) {
logger.Error(err, "Error retrieving lease lock", "lock", le.config.Lock.Describe())
return false
// 其他错误（网络/权限）→ 失败
}
// Lease 不存在 → 创建
if err = le.config.Lock.Create(ctx, leaderElectionRecord); err != nil {
logger.Error(err, "Error initially creating lease lock", "lock", le.config.Lock.Describe())
return false
}
le.setObservedRecord(&leaderElectionRecord)
return true
// 创建成功 → 成为领导者
}
// ═══ 步骤3: 检查当前租约状态 ═══
// 如果 raw record 发生变化 → 更新本地观测
if !bytes.Equal(le.observedRawRecord, oldLeaderElectionRawRecord) {
le.setObservedRecord(oldLeaderElectionRecord)
le.observedRawRecord = oldLeaderElectionRawRecord
}
// 检查：是否有持有者 + 租约是否有效 + 自己不是领导者
if len(oldLeaderElectionRecord.HolderIdentity) > 0 &&
le.isLeaseValid(now.Time) &&
!le.IsLeader() {
// 有其他领导者且租约未过期 → 不能抢
logger.V(4).Info("Lease is held by and has not yet expired",
"lock", le.config.Lock.Describe(),
"holder", oldLeaderElectionRecord.HolderIdentity)
return false
}
// ═══ 步骤4: 尝试更新（获取或续约）═══
if le.IsLeader() {
// 自己是领导者 → 续约（Slow Path）
leaderElectionRecord.AcquireTime = oldLeaderElectionRecord.AcquireTime
// 保持获取时间
leaderElectionRecord.LeaderTransitions = oldLeaderElectionRecord.LeaderTransitions
// 保持转移次数
le.metrics.slowpathExercised(le.config.Name)
// 记录走了 Slow Path（监控用）
} else {
// 自己不是领导者 → 获取领导权
leaderElectionRecord.LeaderTransitions = oldLeaderElectionRecord.LeaderTransitions + 1
// 转移次数 +1
}
// 执行 Update
if err = le.config.Lock.Update(ctx, leaderElectionRecord); err != nil {
logger.Error(err, "Failed to update lease", "lock", le.config.Lock.Describe())
return false
}
le.setObservedRecord(&leaderElectionRecord)
return true
}tryAcquireOrRenew 完整决策流程：
#mermaid-svg-MDa320m5FqdUxzRZ{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-MDa320m5FqdUxzRZ .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-MDa320m5FqdUxzRZ .error-icon{fill:#552222;}#mermaid-svg-MDa320m5FqdUxzRZ .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-MDa320m5FqdUxzRZ .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-MDa320m5FqdUxzRZ .marker{fill:#333333;stroke:#333333;}#mermaid-svg-MDa320m5FqdUxzRZ .marker.cross{stroke:#333333;}#mermaid-svg-MDa320m5FqdUxzRZ svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-MDa320m5FqdUxzRZ p{margin:0;}#mermaid-svg-MDa320m5FqdUxzRZ .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-MDa320m5FqdUxzRZ .cluster-label text{fill:#333;}#mermaid-svg-MDa320m5FqdUxzRZ .cluster-label span{color:#333;}#mermaid-svg-MDa320m5FqdUxzRZ .cluster-label span p{background-color:transparent;}#mermaid-svg-MDa320m5FqdUxzRZ .label text,#mermaid-svg-MDa320m5FqdUxzRZ span{fill:#333;color:#333;}#mermaid-svg-MDa320m5FqdUxzRZ .node rect,#mermaid-svg-MDa320m5FqdUxzRZ .node circle,#mermaid-svg-MDa320m5FqdUxzRZ .node ellipse,#mermaid-svg-MDa320m5FqdUxzRZ .node polygon,#mermaid-svg-MDa320m5FqdUxzRZ .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-MDa320m5FqdUxzRZ .rough-node .label text,#mermaid-svg-MDa320m5FqdUxzRZ .node .label text,#mermaid-svg-MDa320m5FqdUxzRZ .image-shape .label,#mermaid-svg-MDa320m5FqdUxzRZ .icon-shape .label{text-anchor:middle;}#mermaid-svg-MDa320m5FqdUxzRZ .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-MDa320m5FqdUxzRZ .rough-node .label,#mermaid-svg-MDa320m5FqdUxzRZ .node .label,#mermaid-svg-MDa320m5FqdUxzRZ .image-shape .label,#mermaid-svg-MDa320m5FqdUxzRZ .icon-shape .label{text-align:center;}#mermaid-svg-MDa320m5FqdUxzRZ .node.clickable{cursor:pointer;}#mermaid-svg-MDa320m5FqdUxzRZ .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-MDa320m5FqdUxzRZ .arrowheadPath{fill:#333333;}#mermaid-svg-MDa320m5FqdUxzRZ .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-MDa320m5FqdUxzRZ .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-MDa320m5FqdUxzRZ .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-MDa320m5FqdUxzRZ .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-MDa320m5FqdUxzRZ .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-MDa320m5FqdUxzRZ .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-MDa320m5FqdUxzRZ .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-MDa320m5FqdUxzRZ .cluster text{fill:#333;}#mermaid-svg-MDa320m5FqdUxzRZ .cluster span{color:#333;}#mermaid-svg-MDa320m5FqdUxzRZ div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-MDa320m5FqdUxzRZ .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-MDa320m5FqdUxzRZ rect.text{fill:none;stroke-width:0;}#mermaid-svg-MDa320m5FqdUxzRZ .icon-shape,#mermaid-svg-MDa320m5FqdUxzRZ .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-MDa320m5FqdUxzRZ .icon-shape p,#mermaid-svg-MDa320m5FqdUxzRZ .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-MDa320m5FqdUxzRZ .icon-shape .label rect,#mermaid-svg-MDa320m5FqdUxzRZ .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-MDa320m5FqdUxzRZ .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-MDa320m5FqdUxzRZ .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-MDa320m5FqdUxzRZ :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} Yes
Yes
No
No
NotFound
Yes
No
其他错误
nil
变化
未变化
Yes
No
Yes
No
Yes
No
tryAcquireOrRenew(ctx)
构造 leaderElectionRecord
Holder=自己, RenewTime=now, AcquireTime=now
Fast Path: IsLeader() && isLeaseValid()?
Lock.Update(乐观)
Update 成功?
return true (Fast Path)
回退到 Slow Path
Lock.Get() → oldRecord, oldRaw
err?
Lock.Create(record)
Create 成功?
return true
return false
raw record 变化?
setObservedRecord + observedRawRecord
有持有者 && 租约有效 && 不是自己?
return false
(租约被他人持有)
IsLeader()?
续约 Slow Path:
保持 AcquireTime + Transitions
metrics.slowpathExercised
获取领导权:
Transitions + 1
Lock.Update(record)
Update 成功?
setObservedRecord
return true
return false
3.6 tryCoordinatedRenew --- 协调模式续约
go
func (le *LeaderElector) tryCoordinatedRenew(ctx context.Context) bool {
logger := klog.FromContext(ctx)
now := metav1.NewTime(le.clock.Now())
leaderElectionRecord := rl.LeaderElectionRecord{
HolderIdentity: le.config.Lock.Identity(),
LeaseDurationSeconds: int(le.config.LeaseDuration / time.Second),
RenewTime: now,
AcquireTime: now,
}
// ─── 步骤1: 获取当前 Lease ───
oldLeaderElectionRecord, oldLeaderElectionRawRecord, err := le.config.Lock.Get(ctx)
if err != nil {
if !errors.IsNotFound(err) {
logger.Error(err, "Error retrieving lease lock")
return false
}
logger.Info("Lease lock not found")
return false
// 注意：协调模式下 NotFound 直接返回 false，不尝试 Create
// 因为协调选举需要通过 LeaseCandidate 协商
}
// ─── 步骤2: 检查租约状态 ───
if !bytes.Equal(le.observedRawRecord, oldLeaderElectionRawRecord) {
le.setObservedRecord(oldLeaderElectionRecord)
le.observedRawRecord = oldLeaderElectionRawRecord
}
// 检查租约是否过期
le.observedRecordLock.RLock()
obsTime := le.observedTime
le.observedRecordLock.RUnlock()
hasExpired := obsTime.Add(time.Second * time.Duration(oldLeaderElectionRecord.LeaseDurationSeconds)).Before(now.Time)
if hasExpired {
logger.Info("Lease has expired")
return false
}
// 自己不是领导者 → 不能续约
if !le.IsLeader() {
logger.V(6).Info("Lease is held and has not yet expired",
"holder", oldLeaderElectionRecord.HolderIdentity)
return false
}
// ─── 步骤2b: 检查是否被标记为 "任期结束" ───
// 如果 Lease 上有 PreferredHolder，意味着协调选举已选出新的偏好领导者
// 当前持有者应该停止续约，让新领导者接管
if le.IsLeader() && oldLeaderElectionRecord.PreferredHolder != "" {
logger.V(4).Info("Lease is marked as 'end of term'")
return false
// 不续约 → 租约自然过期 → PreferredHolder 接管
}
// ─── 步骤3: 更新 Lease ───
if le.IsLeader() {
leaderElectionRecord.AcquireTime = oldLeaderElectionRecord.AcquireTime
leaderElectionRecord.LeaderTransitions = oldLeaderElectionRecord.LeaderTransitions
leaderElectionRecord.Strategy = oldLeaderElectionRecord.Strategy
le.metrics.slowpathExercised(le.config.Name)
} else {
leaderElectionRecord.LeaderTransitions = oldLeaderElectionRecord.LeaderTransitions + 1
}
if err = le.config.Lock.Update(ctx, leaderElectionRecord); err != nil {
logger.Error(err, "Failed to update lock")
return false
}
le.setObservedRecord(&leaderElectionRecord)
return true
}协调模式 vs 标准模式差异：
#mermaid-svg-SK4YMuYZBvygrjGw{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-SK4YMuYZBvygrjGw .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-SK4YMuYZBvygrjGw .error-icon{fill:#552222;}#mermaid-svg-SK4YMuYZBvygrjGw .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-SK4YMuYZBvygrjGw .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-SK4YMuYZBvygrjGw .marker{fill:#333333;stroke:#333333;}#mermaid-svg-SK4YMuYZBvygrjGw .marker.cross{stroke:#333333;}#mermaid-svg-SK4YMuYZBvygrjGw svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-SK4YMuYZBvygrjGw p{margin:0;}#mermaid-svg-SK4YMuYZBvygrjGw .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-SK4YMuYZBvygrjGw .cluster-label text{fill:#333;}#mermaid-svg-SK4YMuYZBvygrjGw .cluster-label span{color:#333;}#mermaid-svg-SK4YMuYZBvygrjGw .cluster-label span p{background-color:transparent;}#mermaid-svg-SK4YMuYZBvygrjGw .label text,#mermaid-svg-SK4YMuYZBvygrjGw span{fill:#333;color:#333;}#mermaid-svg-SK4YMuYZBvygrjGw .node rect,#mermaid-svg-SK4YMuYZBvygrjGw .node circle,#mermaid-svg-SK4YMuYZBvygrjGw .node ellipse,#mermaid-svg-SK4YMuYZBvygrjGw .node polygon,#mermaid-svg-SK4YMuYZBvygrjGw .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-SK4YMuYZBvygrjGw .rough-node .label text,#mermaid-svg-SK4YMuYZBvygrjGw .node .label text,#mermaid-svg-SK4YMuYZBvygrjGw .image-shape .label,#mermaid-svg-SK4YMuYZBvygrjGw .icon-shape .label{text-anchor:middle;}#mermaid-svg-SK4YMuYZBvygrjGw .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-SK4YMuYZBvygrjGw .rough-node .label,#mermaid-svg-SK4YMuYZBvygrjGw .node .label,#mermaid-svg-SK4YMuYZBvygrjGw .image-shape .label,#mermaid-svg-SK4YMuYZBvygrjGw .icon-shape .label{text-align:center;}#mermaid-svg-SK4YMuYZBvygrjGw .node.clickable{cursor:pointer;}#mermaid-svg-SK4YMuYZBvygrjGw .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-SK4YMuYZBvygrjGw .arrowheadPath{fill:#333333;}#mermaid-svg-SK4YMuYZBvygrjGw .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-SK4YMuYZBvygrjGw .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-SK4YMuYZBvygrjGw .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-SK4YMuYZBvygrjGw .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-SK4YMuYZBvygrjGw .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-SK4YMuYZBvygrjGw .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-SK4YMuYZBvygrjGw .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-SK4YMuYZBvygrjGw .cluster text{fill:#333;}#mermaid-svg-SK4YMuYZBvygrjGw .cluster span{color:#333;}#mermaid-svg-SK4YMuYZBvygrjGw div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-SK4YMuYZBvygrjGw .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-SK4YMuYZBvygrjGw rect.text{fill:none;stroke-width:0;}#mermaid-svg-SK4YMuYZBvygrjGw .icon-shape,#mermaid-svg-SK4YMuYZBvygrjGw .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-SK4YMuYZBvygrjGw .icon-shape p,#mermaid-svg-SK4YMuYZBvygrjGw .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-SK4YMuYZBvygrjGw .icon-shape .label rect,#mermaid-svg-SK4YMuYZBvygrjGw .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-SK4YMuYZBvygrjGw .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-SK4YMuYZBvygrjGw .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-SK4YMuYZBvygrjGw :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} 协调模式
tryCoordinatedRenew
无 Fast Path
Lease 不存在 → 直接返回 false
租约过期 → 返回 false
PreferredHolder ≠ '' → 停止续约
标准模式
tryAcquireOrRenew
Fast Path 乐观更新
Lease 不存在 → Create
租约过期 → 尝试获取
| 维度 | 标准模式 | 协调模式 |
|---|---|---|
| Fast Path | ✅ 乐观更新 | ❌ 必须先 Get |
| Lease 不存在 | Create | 返回 false |
| 自己不是领导者 | 可抢（租约过期时） | 不可抢 |
| PreferredHolder | 不检查 | 检查 → 停止续约 |
| Strategy 字段 | 不传递 | 传递 |
| 适用场景 | 竞争选举 | 协商选举（优雅切换） |
3.7 release --- 主动释放租约
go
func (le *LeaderElector) release(logger klog.Logger) bool {
ctx := context.Background()
// 使用 Background 而非传入的 ctx
// 因为传入的 ctx 可能已经取消了
// 但我们仍需要完成释放操作
timeoutCtx, timeoutCancel := context.WithTimeout(ctx, le.config.RenewDeadline)
defer timeoutCancel()
// 设置超时，避免释放操作永久阻塞
// ─── 获取当前 Lease 状态 ───
oldLeaderElectionRecord, _, err := le.config.Lock.Get(timeoutCtx)
if err != nil {
if !errors.IsNotFound(err) {
logger.Error(err, "error retrieving resource lock")
return false
}
logger.Info("lease lock not found")
return false
// Lease 已不存在 → 无需释放
}
// ─── 检查自己是否仍是领导者 ───
if !le.IsLeader() {
return true
// 不是领导者 → 无需释放
}
// ─── 构造释放记录 ───
now := metav1.NewTime(le.clock.Now())
leaderElectionRecord := rl.LeaderElectionRecord{
LeaderTransitions: oldLeaderElectionRecord.LeaderTransitions,
// 保持转移次数
LeaseDurationSeconds: 1,
// 设为 1 秒 → 租约立即过期
RenewTime: now,
AcquireTime: now,
// HolderIdentity 默认为零值（空字符串）
// 空字符串 = 没有持有者 → 其他候选者可立即竞争
}
// ─── 更新 Lease ───
if err := le.config.Lock.Update(timeoutCtx, leaderElectionRecord); err != nil {
logger.Error(err, "Failed to release lease")
return false
}
le.setObservedRecord(&leaderElectionRecord)
return true
}释放策略 ：将 LeaseDurationSeconds 设为 1 且 HolderIdentity 清空，使其他候选者无需等待完整的 LeaseDuration 就能接管。
3.8 maybeReportTransition --- 领导权转移通知
go
func (le *LeaderElector) maybeReportTransition() {
// ─── 检查是否有变化 ───
if le.observedRecord.HolderIdentity == le.reportedLeader {
return
// 观测到的领导者与已报告的相同 → 无需通知
}
// ─── 更新已报告的领导者 ───
le.reportedLeader = le.observedRecord.HolderIdentity
// ─── 异步通知 ───
if le.config.Callbacks.OnNewLeader != nil {
go le.config.Callbacks.OnNewLeader(le.reportedLeader)
// 使用 goroutine 异步调用
// 避免阻塞选举主循环
}
}3.9 isLeaseValid --- 租约有效性检查
go
func (le *LeaderElector) isLeaseValid(now time.Time) bool {
le.observedRecordLock.RLock()
defer le.observedRecordLock.RUnlock()
// 租约是否仍然有效：
// observedTime + LeaseDurationSeconds > now
// 即：从上次观测时间算起，租约还没过期
return le.observedTime.Add(
time.Second * time.Duration(le.observedRecord.LeaseDurationSeconds),
).After(now)
}3.10 Check --- 健康检查
go
func (le *LeaderElector) Check(maxTolerableExpiredLease time.Duration) error {
// ─── 不是领导者 → 健康 ───
if !le.IsLeader() {
return nil
// 非领导者不需要续约 → 无所谓健康
}
// ─── 是领导者 → 检查续约是否超时 ───
le.observedRecordLock.RLock()
lastObservation := le.observedTime
leaseDuration := le.config.LeaseDuration
le.observedRecordLock.RUnlock()
// 如果距离上次观测已超过 LeaseDuration + 容忍时间
// 说明续约已失败但进程未退出（可能是死锁）
if le.clock.Since(lastObservation) > leaseDuration+maxTolerableExpiredLease {
return fmt.Errorf("failed election to renew leadership on lease %s", le.config.Name)
}
return nil
}健康检查的时间窗口：
#mermaid-svg-bVXDIuCbSmJfMJXn{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-bVXDIuCbSmJfMJXn .error-icon{fill:#552222;}#mermaid-svg-bVXDIuCbSmJfMJXn .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-bVXDIuCbSmJfMJXn .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-bVXDIuCbSmJfMJXn .marker{fill:#333333;stroke:#333333;}#mermaid-svg-bVXDIuCbSmJfMJXn .marker.cross{stroke:#333333;}#mermaid-svg-bVXDIuCbSmJfMJXn svg{font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-bVXDIuCbSmJfMJXn p{margin:0;}#mermaid-svg-bVXDIuCbSmJfMJXn .label{font-family:"trebuchet ms",verdana,arial,sans-serif;color:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster-label text{fill:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster-label span{color:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster-label span p{background-color:transparent;}#mermaid-svg-bVXDIuCbSmJfMJXn .label text,#mermaid-svg-bVXDIuCbSmJfMJXn span{fill:#333;color:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn .node rect,#mermaid-svg-bVXDIuCbSmJfMJXn .node circle,#mermaid-svg-bVXDIuCbSmJfMJXn .node ellipse,#mermaid-svg-bVXDIuCbSmJfMJXn .node polygon,#mermaid-svg-bVXDIuCbSmJfMJXn .node path{fill:#ECECFF;stroke:#9370DB;stroke-width:1px;}#mermaid-svg-bVXDIuCbSmJfMJXn .rough-node .label text,#mermaid-svg-bVXDIuCbSmJfMJXn .node .label text,#mermaid-svg-bVXDIuCbSmJfMJXn .image-shape .label,#mermaid-svg-bVXDIuCbSmJfMJXn .icon-shape .label{text-anchor:middle;}#mermaid-svg-bVXDIuCbSmJfMJXn .node .katex path{fill:#000;stroke:#000;stroke-width:1px;}#mermaid-svg-bVXDIuCbSmJfMJXn .rough-node .label,#mermaid-svg-bVXDIuCbSmJfMJXn .node .label,#mermaid-svg-bVXDIuCbSmJfMJXn .image-shape .label,#mermaid-svg-bVXDIuCbSmJfMJXn .icon-shape .label{text-align:center;}#mermaid-svg-bVXDIuCbSmJfMJXn .node.clickable{cursor:pointer;}#mermaid-svg-bVXDIuCbSmJfMJXn .root .anchor path{fill:#333333!important;stroke-width:0;stroke:#333333;}#mermaid-svg-bVXDIuCbSmJfMJXn .arrowheadPath{fill:#333333;}#mermaid-svg-bVXDIuCbSmJfMJXn .edgePath .path{stroke:#333333;stroke-width:2.0px;}#mermaid-svg-bVXDIuCbSmJfMJXn .flowchart-link{stroke:#333333;fill:none;}#mermaid-svg-bVXDIuCbSmJfMJXn .edgeLabel{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-bVXDIuCbSmJfMJXn .edgeLabel p{background-color:rgba(232,232,232, 0.8);}#mermaid-svg-bVXDIuCbSmJfMJXn .edgeLabel rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-bVXDIuCbSmJfMJXn .labelBkg{background-color:rgba(232, 232, 232, 0.5);}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster rect{fill:#ffffde;stroke:#aaaa33;stroke-width:1px;}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster text{fill:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn .cluster span{color:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:"trebuchet ms",verdana,arial,sans-serif;font-size:12px;background:hsl(80, 100%, 96.2745098039%);border:1px solid #aaaa33;border-radius:2px;pointer-events:none;z-index:100;}#mermaid-svg-bVXDIuCbSmJfMJXn .flowchartTitleText{text-anchor:middle;font-size:18px;fill:#333;}#mermaid-svg-bVXDIuCbSmJfMJXn rect.text{fill:none;stroke-width:0;}#mermaid-svg-bVXDIuCbSmJfMJXn .icon-shape,#mermaid-svg-bVXDIuCbSmJfMJXn .image-shape{background-color:rgba(232,232,232, 0.8);text-align:center;}#mermaid-svg-bVXDIuCbSmJfMJXn .icon-shape p,#mermaid-svg-bVXDIuCbSmJfMJXn .image-shape p{background-color:rgba(232,232,232, 0.8);padding:2px;}#mermaid-svg-bVXDIuCbSmJfMJXn .icon-shape .label rect,#mermaid-svg-bVXDIuCbSmJfMJXn .image-shape .label rect{opacity:0.5;background-color:rgba(232,232,232, 0.8);fill:rgba(232,232,232, 0.8);}#mermaid-svg-bVXDIuCbSmJfMJXn .label-icon{display:inline-block;height:1em;overflow:visible;vertical-align:-0.125em;}#mermaid-svg-bVXDIuCbSmJfMJXn .node .label-icon path{fill:currentColor;stroke:revert;stroke-width:revert;}#mermaid-svg-bVXDIuCbSmJfMJXn :root{--mermaid-font-family:"trebuchet ms",verdana,arial,sans-serif;} 健康状态
时间线
正常续约
仍在容忍窗口内
超过容忍窗口
observedTime
observedTime +
LeaseDuration
observedTime +
LeaseDuration +
maxTolerableExpired
健康 (Check returns nil)
不健康 (Check returns error)