深度了解flink(十) JobManager(4) ResourceManager HA
ResourceManager（ZK模式）的高可用启动流程
ResourceManager启动流程在DefaultDispatcherResourceManagerComponentFactory#create中
public DispatcherResourceManagerComponent create(Configuration configuration,ResourceID resourceId,Executor ioExecutor,RpcService rpcService,HighAvailabilityServices highAvailabilityServices,BlobServer blobServer,HeartbeatServices heartbeatServices,DelegationTokenManager delegationTokenManager,MetricRegistry metricRegistry,ExecutionGraphInfoStore executionGraphInfoStore,MetricQueryServiceRetriever metricQueryServiceRetriever,Collection<FailureEnricher> failureEnrichers,FatalErrorHandler fatalErrorHandler)throws Exception {//resourcemanager的选举服务LeaderRetrievalService resourceManagerRetrievalService = null;ResourceManagerService resourceManagerService = null;try {//resourceManager leader 获取服务resourceManagerRetrievalService =highAvailabilityServices.getResourceManagerLeaderRetriever();//LeaderGatewayRetriever实现了LeaderRetrievalListener接口final LeaderGatewayRetriever<ResourceManagerGateway> resourceManagerGatewayRetriever =new RpcGatewayRetriever<>(rpcService,ResourceManagerGateway.class,ResourceManagerId::fromUuid,new ExponentialBackoffRetryStrategy(12, Duration.ofMillis(10), Duration.ofMillis(50)));resourceManagerService =ResourceManagerServiceImpl.create(resourceManagerFactory,configuration,resourceId,rpcService,highAvailabilityServices,heartbeatServices,delegationTokenManager,fatalErrorHandler,new ClusterInformation(hostname, blobServer.getPort()),webMonitorEndpoint.getRestBaseUrl(),metricRegistry,hostname,ioExecutor);//启动resourceManagerService start方法会调用具体的选举方法resourceManagerService.start();//启动etrievalService服务的start方法，resourceManagerRetrievalService.start(resourceManagerGatewayRetriever);return new DispatcherResourceManagerComponent(dispatcherRunner,resourceManagerService,dispatcherLeaderRetrievalService,resourceManagerRetrievalService,webMonitorEndpoint,fatalErrorHandler,dispatcherOperationCaches);} catch (Exception exception) {//省略无关代码}}初始化LeaderRetrievalServer
resourceManagerRetrievalService =highAvailabilityServices.getResourceManagerLeaderRetriever();getResourceManagerLeaderRetriever会调用父类AbstractHaServices的这个方法
@Overridepublic LeaderRetrievalService getResourceManagerLeaderRetriever() {return createLeaderRetrievalService(getLeaderPathForResourceManager());}
createLeaderRetrievalService会调用具体子类的方法，zk模式下会走到ZooKeeperLeaderElectionHaServices下
@Overrideprotected LeaderRetrievalService createLeaderRetrievalService(String componentId) {// Maybe use a single service for leader retrievalreturn ZooKeeperUtils.createLeaderRetrievalService(curatorFrameworkWrapper.asCuratorFramework(),ZooKeeperUtils.getLeaderPath(componentId),configuration);}继续方法跟进
public static DefaultLeaderRetrievalService createLeaderRetrievalService(final CuratorFramework client, final String path, final Configuration configuration) {return new DefaultLeaderRetrievalService(createLeaderRetrievalDriverFactory(client, path, configuration));最终调用DefaultLeaderRetrievalService的构造方法进行初始化，入参是一个LeaderRetrievalDriverFactory接口，zk模式下是ZooKeeperLeaderRetrievalDriverFactory
初始化LeaderRetrievalListener
final LeaderGatewayRetriever<DispatcherGateway> dispatcherGatewayRetriever =new RpcGatewayRetriever<>(rpcService,DispatcherGateway.class,DispatcherId::fromUuid,new ExponentialBackoffRetryStrategy(12, Duration.ofMillis(10), Duration.ofMillis(50)));RpcGatewayRetrieverUML类图如下
LeaderGatewayRetriever#notifyNewLeaderAddress对LeaderRetrievalListener#notifyLeaderAddress做了实现
@Overridepublic void notifyNewLeaderAddress(CompletableFuture<Tuple2<String, UUID>> newLeaderAddressFuture) {final CompletableFuture<T> newGatewayFuture = createGateway(newLeaderAddressFuture);final CompletableFuture<T> oldGatewayFuture =atomicGatewayFuture.getAndSet(newGatewayFuture);newGatewayFuture.whenComplete((t, throwable) -> {if (throwable != null) {oldGatewayFuture.completeExceptionally(throwable);} else {oldGatewayFuture.complete(t);}});}创建ResourceManagerService
resourceManagerService =ResourceManagerServiceImpl.create(resourceManagerFactory,configuration,resourceId,rpcService,highAvailabilityServices,heartbeatServices,delegationTokenManager,fatalErrorHandler,new ClusterInformation(hostname, blobServer.getPort()),webMonitorEndpoint.getRestBaseUrl(),metricRegistry,hostname,ioExecutor);ResourceManagerService负责管理ResourceManager的生命周期，也负责haServer的启动
创建LeaderElection
private ResourceManagerServiceImpl(ResourceManagerFactory<?> resourceManagerFactory,ResourceManagerProcessContext rmProcessContext)throws Exception {//省略其他方法//LeaderElection进行了初始化this.leaderElection =rmProcessContext.getHighAvailabilityServices().getResourceManagerLeaderElection();LeaderElection选举
resourceManagerService.start();跳转到start方法
public void start() throws Exception {synchronized (lock) {if (running) {LOG.debug("Resource manager service has already started.");return;}running = true;}LOG.info("Starting resource manager service.");leaderElection.startLeaderElection(this);}leaderElection.startLeaderElection(this)zk模式下走的是DefaultLeaderElection的方法，
@Overridepublic void startLeaderElection(LeaderContender contender) throws Exception {Preconditions.checkNotNull(contender);parentService.register(componentId, contender);}
开始对参选者进行注册
protected void register(String componentId, LeaderContender contender) throws Exception {checkNotNull(componentId, "componentId must not be null.");checkNotNull(contender, "Contender must not be null.");synchronized (lock) {if (leaderElectionDriver == null) {createLeaderElectionDriver();}//省略无关代码}register会判断选举的driver是否存在，如果不存在，则根据高可用的模式进行选举驱动的创建
@Overridepublic ZooKeeperLeaderElectionDriver create(LeaderElectionDriver.Listener leaderElectionListener) throws Exception {return new ZooKeeperLeaderElectionDriver(curatorFramework, leaderElectionListener);}ZooKeeperLeaderElectionDriver初始化
public ZooKeeperLeaderElectionDriver(CuratorFramework curatorFramework, LeaderElectionDriver.Listener leaderElectionListener)throws Exception {//参数校验this.curatorFramework = Preconditions.checkNotNull(curatorFramework);this.leaderElectionListener = Preconditions.checkNotNull(leaderElectionListener);//使用ZooKeeperUtils.generateLeaderLatchPath方法基于curatorFramework的命名空间生成一个ZooKeeper节点路径，该路径通常用于领导者选举的锁。this.leaderLatchPath =ZooKeeperUtils.generateLeaderLatchPath(curatorFramework.getNamespace());//使用CuratorFramework和之前生成的路径创建一个LeaderLatch实例。LeaderLatch是Curator提供的一个领导者选举实现。 this.leaderLatch = new LeaderLatch(curatorFramework, ZooKeeperUtils.getLeaderLatchPath());//使用ZooKeeperUtils.createTreeCache方法创建一个TreeCache实例，用于监听ZooKeeper中特定路径（这里是根路径"/"）下的节点变化this.treeCache =ZooKeeperUtils.createTreeCache(curatorFramework,"/",new ZooKeeperLeaderElectionDriver.ConnectionInfoNodeSelector());treeCache.getListenable().addListener((client, event) -> {switch (event.getType()) {case NODE_ADDED:case NODE_UPDATED:Preconditions.checkNotNull(event.getData(),"The ZooKeeper event data must not be null.");handleChangedLeaderInformation(event.getData());break;case NODE_REMOVED:Preconditions.checkNotNull(event.getData(),"The ZooKeeper event data must not be null.");handleRemovedLeaderInformation(event.getData().getPath());break;}});leaderLatch.addListener(this);curatorFramework.getConnectionStateListenable().addListener(listener);leaderLatch.start();treeCache.start();}ZooKeeperLeaderElectionDriver.handleStateChange
状态变化时候根据不同状态打印日志
private void handleStateChange(ConnectionState newState) {switch (newState) {case CONNECTED:LOG.debug("Connected to ZooKeeper quorum. Leader election can start.");break;case SUSPENDED:LOG.warn("Connection to ZooKeeper suspended, waiting for reconnection.");break;case RECONNECTED:LOG.info("Connection to ZooKeeper was reconnected. Leader election can be restarted.");break;case LOST:// Maybe we have to throw an exception here to terminate the JobManagerLOG.warn("Connection to ZooKeeper lost. None of the contenders participates in the leader election anymore.");break;}}DefaultLeaderElectionService.notifyLeaderContenderOfLeadership
private void notifyLeaderContenderOfLeadership(String componentId, UUID sessionID) {if (!leaderContenderRegistry.containsKey(componentId)) {LOG.debug("The grant leadership notification for session ID {} is not forwarded because the DefaultLeaderElectionService ({}) has no contender registered.",sessionID,leaderElectionDriver);return;} else if (!sessionID.equals(issuedLeaderSessionID)) {LOG.debug("An out-dated leadership-acquired event with session ID {} was triggered. The current leader session ID is {}. The event will be ignored.",sessionID,issuedLeaderSessionID);return;}Preconditions.checkState(!confirmedLeaderInformation.hasLeaderInformation(componentId),"The leadership should have been granted while not having the leadership acquired.");LOG.debug("Granting leadership to the contender registered under component '{}' with session ID {}.",componentId,issuedLeaderSessionID);leaderContenderRegistry.get(componentId).grantLeadership(issuedLeaderSessionID);}