聊聊PowerJob Server的高可用

序

本文主要研究一下PowerJob Server的高可用

PowerJobSpringWorker

tech/powerjob/worker/PowerJobSpringWorker.java

public class PowerJobSpringWorker implements ApplicationContextAware, InitializingBean, DisposableBean {

    /**
     * 组合优于继承，持有 PowerJobWorker，内部重新设置 ProcessorFactory 更优雅
     */
    private PowerJobWorker powerJobWorker;
    private final PowerJobWorkerConfig config;

    public PowerJobSpringWorker(PowerJobWorkerConfig config) {
        this.config = config;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        powerJobWorker = new PowerJobWorker(config);
        powerJobWorker.init();
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        BuiltInSpringProcessorFactory springProcessorFactory = new BuiltInSpringProcessorFactory(applicationContext);

        BuildInSpringMethodProcessorFactory springMethodProcessorFactory = new BuildInSpringMethodProcessorFactory(applicationContext);
        // append BuiltInSpringProcessorFactory

        List<ProcessorFactory> processorFactories = Lists.newArrayList(
                Optional.ofNullable(config.getProcessorFactoryList())
                        .orElse(Collections.emptyList()));
        processorFactories.add(springProcessorFactory);
        processorFactories.add(springMethodProcessorFactory);
        config.setProcessorFactoryList(processorFactories);
    }

    @Override
    public void destroy() throws Exception {
        powerJobWorker.destroy();
    }
}

PowerJobSpringWorker实现了InitializingBean接口，其afterPropertiesSet会创建powerJobWorker，然后执行其init方法

PowerJobWorker.init

tech/powerjob/worker/PowerJobWorker.java

    public void init() throws Exception {

        if (!initialized.compareAndSet(false, true)) {
            log.warn("[PowerJobWorker] please do not repeat the initialization");
            return;
        }

        Stopwatch stopwatch = Stopwatch.createStarted();
        log.info("[PowerJobWorker] start to initialize PowerJobWorker...");

        PowerJobWorkerConfig config = workerRuntime.getWorkerConfig();
        CommonUtils.requireNonNull(config, "can't find PowerJobWorkerConfig, please set PowerJobWorkerConfig first");

        ServerDiscoveryService serverDiscoveryService = new PowerJobServerDiscoveryService(config);
        workerRuntime.setServerDiscoveryService(serverDiscoveryService);

        try {
            PowerBannerPrinter.print();
            // 校验 appName
            WorkerAppInfo appInfo = serverDiscoveryService.assertApp();
            workerRuntime.setAppInfo(appInfo);

            // 初始化网络数据，区别对待上报地址和本机绑定地址（对外统一使用上报地址）
            String localBindIp = NetUtils.getLocalHost();
            int localBindPort = config.getPort();
            String externalIp = PropertyUtils.readProperty(PowerJobDKey.NT_EXTERNAL_ADDRESS, localBindIp);
            String externalPort = PropertyUtils.readProperty(PowerJobDKey.NT_EXTERNAL_PORT, String.valueOf(localBindPort));
            log.info("[PowerJobWorker] [ADDRESS_INFO] localBindIp: {}, localBindPort: {}; externalIp: {}, externalPort: {}", localBindIp, localBindPort, externalIp, externalPort);
            workerRuntime.setWorkerAddress(Address.toFullAddress(externalIp, Integer.parseInt(externalPort)));

            // 初始化 线程池
            final ExecutorManager executorManager = new ExecutorManager(workerRuntime.getWorkerConfig());
            workerRuntime.setExecutorManager(executorManager);

            // 初始化 ProcessorLoader
            ProcessorLoader processorLoader = buildProcessorLoader(workerRuntime);
            workerRuntime.setProcessorLoader(processorLoader);

            // 初始化 actor
            TaskTrackerActor taskTrackerActor = new TaskTrackerActor(workerRuntime);
            ProcessorTrackerActor processorTrackerActor = new ProcessorTrackerActor(workerRuntime);
            WorkerActor workerActor = new WorkerActor(workerRuntime, taskTrackerActor);

            // 初始化通讯引擎
            EngineConfig engineConfig = new EngineConfig()
                    .setType(config.getProtocol().name())
                    .setServerType(ServerType.WORKER)
                    .setBindAddress(new Address().setHost(localBindIp).setPort(localBindPort))
                    .setActorList(Lists.newArrayList(taskTrackerActor, processorTrackerActor, workerActor));

            EngineOutput engineOutput = remoteEngine.start(engineConfig);
            workerRuntime.setTransporter(engineOutput.getTransporter());

            // 连接 server
            serverDiscoveryService.timingCheck(workerRuntime.getExecutorManager().getCoreExecutor());

            log.info("[PowerJobWorker] PowerJobRemoteEngine initialized successfully.");

            // 初始化日志系统
            OmsLogHandler omsLogHandler = new OmsLogHandler(workerRuntime.getWorkerAddress(), workerRuntime.getTransporter(), serverDiscoveryService);
            workerRuntime.setOmsLogHandler(omsLogHandler);

            // 初始化存储
            TaskPersistenceService taskPersistenceService = new TaskPersistenceService(workerRuntime.getWorkerConfig().getStoreStrategy());
            taskPersistenceService.init();
            workerRuntime.setTaskPersistenceService(taskPersistenceService);
            log.info("[PowerJobWorker] local storage initialized successfully.");


            // 初始化定时任务
            workerRuntime.getExecutorManager().getCoreExecutor().scheduleAtFixedRate(new WorkerHealthReporter(workerRuntime), 0, config.getHealthReportInterval(), TimeUnit.SECONDS);
            workerRuntime.getExecutorManager().getCoreExecutor().scheduleWithFixedDelay(omsLogHandler.logSubmitter, 0, 5, TimeUnit.SECONDS);

            log.info("[PowerJobWorker] PowerJobWorker initialized successfully, using time: {}, congratulations!", stopwatch);
        }catch (Exception e) {
            log.error("[PowerJobWorker] initialize PowerJobWorker failed, using {}.", stopwatch, e);
            throw e;
        }
    }

PowerJobWorker的init方法会执行serverDiscoveryService.timingCheck(workerRuntime.getExecutorManager().getCoreExecutor())调度timingCheck

timingCheck

tech/powerjob/worker/background/discovery/PowerJobServerDiscoveryService.java

    public void timingCheck(ScheduledExecutorService timingPool) {
        this.currentServerAddress = discovery();
        if (StringUtils.isEmpty(this.currentServerAddress) && !config.isAllowLazyConnectServer()) {
            throw new PowerJobException("can't find any available server, this worker has been quarantined.");
        }
        // 这里必须保证成功
        timingPool.scheduleAtFixedRate(() -> {
                    try {
                        this.currentServerAddress = discovery();
                    } catch (Exception e) {
                        log.error("[PowerDiscovery] fail to discovery server!", e);
                    }
                }
                , 10, 10, TimeUnit.SECONDS);
    }

PowerJobServerDiscoveryService的timingCheck会使用timingPool定时每隔10s调度执行discovery()来更新当前worker的server地址

discovery

    private String discovery() {

        // 只有允许延迟加载模式下，appId 才可能为空。每次服务发现前，都重新尝试获取 appInfo。由于是懒加载链路，此处完全忽略异常
        if (appInfo.getAppId() == null || appInfo.getAppId() < 0) {
            try {
                assertApp0();
            } catch (Exception e) {
                log.warn("[PowerDiscovery] assertAppName in discovery stage failed, msg: {}", e.getMessage());
                return null;
            }
        }

        if (ip2Address.isEmpty()) {
            config.getServerAddress().forEach(x -> ip2Address.put(x.split(":")[0], x));
        }

        String result = null;

        // 先对当前机器发起请求
        String currentServer = currentServerAddress;
        if (!StringUtils.isEmpty(currentServer)) {
            String ip = currentServer.split(":")[0];
            // 直接请求当前Server的HTTP服务，可以少一次网络开销，减轻Server负担
            String firstServerAddress = ip2Address.get(ip);
            if (firstServerAddress != null) {
                result = acquire(firstServerAddress);
            }
        }

        for (String httpServerAddress : config.getServerAddress()) {
            if (StringUtils.isEmpty(result)) {
                result = acquire(httpServerAddress);
            }else {
                break;
            }
        }

        if (StringUtils.isEmpty(result)) {
            log.warn("[PowerDiscovery] can't find any available server, this worker has been quarantined.");

            // 在 Server 高可用的前提下，连续失败多次，说明该节点与外界失联，Server已经将秒级任务转移到其他Worker，需要杀死本地的任务
            if (FAILED_COUNT++ > MAX_FAILED_COUNT) {

                log.warn("[PowerDiscovery] can't find any available server for 3 consecutive times, It's time to kill all frequent job in this worker.");
                List<Long> frequentInstanceIds = HeavyTaskTrackerManager.getAllFrequentTaskTrackerKeys();
                if (!CollectionUtils.isEmpty(frequentInstanceIds)) {
                    frequentInstanceIds.forEach(instanceId -> {
                        HeavyTaskTracker taskTracker = HeavyTaskTrackerManager.removeTaskTracker(instanceId);
                        taskTracker.destroy();
                        log.warn("[PowerDiscovery] kill frequent instance(instanceId={}) due to can't find any available server.", instanceId);
                    });
                }

                FAILED_COUNT = 0;
            }
            return null;
        } else {
            // 重置失败次数
            FAILED_COUNT = 0;
            log.debug("[PowerDiscovery] current server is {}.", result);
            return result;
        }
    }

discovery方法就是定时遍历配置的serverAddress地址列表，调用server端的acquire方法来获取可用的server

acquireServer

tech/powerjob/server/web/controller/ServerController.java

    @GetMapping("/acquire")
    public ResultDTO<String> acquireServer(ServerDiscoveryRequest request) {
        return ResultDTO.success(serverElectionService.elect(request));
    }

ServerController提供了acquire接口，它执行的是serverElectionService.elect(request)

elect

tech/powerjob/server/remote/server/election/ServerElectionService.java

    public String elect(ServerDiscoveryRequest request) {
        if (!accurate()) {
            final String currentServer = request.getCurrentServer();
            // 如果是本机，就不需要查数据库那么复杂的操作了，直接返回成功
            Optional<ProtocolInfo> localProtocolInfoOpt = Optional.ofNullable(transportService.allProtocols().get(request.getProtocol()));
            if (localProtocolInfoOpt.isPresent()) {
                if (localProtocolInfoOpt.get().getExternalAddress().equals(currentServer) || localProtocolInfoOpt.get().getAddress().equals(currentServer)) {
                    log.info("[ServerElection] this server[{}] is worker[appId={}]'s current server, skip check", currentServer, request.getAppId());
                    return currentServer;
                }
            }
        }
        return getServer0(request);
    }

ServerElectionService的elect方法主要是执行getServer0

getServer0

    private String getServer0(ServerDiscoveryRequest discoveryRequest) {

        final Long appId = discoveryRequest.getAppId();
        final String protocol = discoveryRequest.getProtocol();
        Set<String> downServerCache = Sets.newHashSet();

        for (int i = 0; i < RETRY_TIMES; i++) {

            // 无锁获取当前数据库中的Server
            Optional<AppInfoDO> appInfoOpt = appInfoRepository.findById(appId);
            if (!appInfoOpt.isPresent()) {
                throw new PowerJobException(appId + " is not registered!");
            }
            String appName = appInfoOpt.get().getAppName();
            String originServer = appInfoOpt.get().getCurrentServer();
            String activeAddress = activeAddress(originServer, downServerCache, protocol);
            if (StringUtils.isNotEmpty(activeAddress)) {
                return activeAddress;
            }

            // 无可用Server，重新进行Server选举，需要加锁
            String lockName = String.format(SERVER_ELECT_LOCK, appId);
            boolean lockStatus = lockService.tryLock(lockName, 30000);
            if (!lockStatus) {
                try {
                    Thread.sleep(500);
                }catch (Exception ignore) {
                }
                continue;
            }
            try {

                // 可能上一台机器已经完成了Server选举，需要再次判断
                AppInfoDO appInfo = appInfoRepository.findById(appId).orElseThrow(() -> new RuntimeException("impossible, unless we just lost our database."));
                String address = activeAddress(appInfo.getCurrentServer(), downServerCache, protocol);
                if (StringUtils.isNotEmpty(address)) {
                    return address;
                }

                // 篡位，如果本机存在协议，则作为Server调度该 worker
                final ProtocolInfo targetProtocolInfo = transportService.allProtocols().get(protocol);
                if (targetProtocolInfo != null) {
                    // 注意，写入 AppInfoDO#currentServer 的永远是 default 的绑定地址，仅在返回的时候特殊处理为协议地址
                    appInfo.setCurrentServer(transportService.defaultProtocol().getAddress());
                    appInfo.setGmtModified(new Date());

                    appInfoRepository.saveAndFlush(appInfo);
                    log.info("[ServerElection] this server({}) become the new server for app(appId={}).", appInfo.getCurrentServer(), appId);
                    return targetProtocolInfo.getExternalAddress();
                }
            }catch (Exception e) {
                log.error("[ServerElection] write new server to db failed for app {}.", appName, e);
            } finally {
                lockService.unlock(lockName);
            }
        }
        throw new PowerJobException("server elect failed for app " + appId);
    }

getServer0方法会重试10次，它先针对discoveryRequest指定的currentServer进行activeAddress，成功则返回，没有可用server则加锁进行重新分配，这里优先本机判断

activeAddress

    private String activeAddress(String serverAddress, Set<String> downServerCache, String protocol) {

        if (downServerCache.contains(serverAddress)) {
            return null;
        }
        if (StringUtils.isEmpty(serverAddress)) {
            return null;
        }

        Ping ping = new Ping();
        ping.setCurrentTime(System.currentTimeMillis());

        URL targetUrl = ServerURLFactory.ping2Friend(serverAddress);
        try {
            AskResponse response = transportService.ask(Protocol.HTTP.name(), targetUrl, ping, AskResponse.class)
                    .toCompletableFuture()
                    .get(PING_TIMEOUT_MS, TimeUnit.MILLISECONDS);
            if (response.isSuccess()) {
                // 检测通过的是远程 server 的暴露地址，需要返回 worker 需要的协议地址
                final JSONObject protocolInfo = JsonUtils.parseObject(response.getData(), JSONObject.class).getJSONObject(protocol);
                if (protocolInfo != null) {
                    downServerCache.remove(serverAddress);
                    ProtocolInfo remoteProtocol = protocolInfo.toJavaObject(ProtocolInfo.class);
                    log.info("[ServerElection] server[{}] is active, it will be the master, final protocol={}", serverAddress, remoteProtocol);
                    // 4.3.3 升级 4.3.4 过程中，未升级的 server 还不存在 externalAddress，需要使用 address 兼容
                    return Optional.ofNullable(remoteProtocol.getExternalAddress()).orElse(remoteProtocol.getAddress());
                } else {
                    log.warn("[ServerElection] server[{}] is active but don't have target protocol", serverAddress);
                }
            }
        } catch (TimeoutException te) {
            log.warn("[ServerElection] server[{}] was down due to ping timeout!", serverAddress);
        } catch (Exception e) {
            log.warn("[ServerElection] server[{}] was down with unknown case!", serverAddress, e);
        }
        downServerCache.add(serverAddress);
        return null;
    }

activeAddress方法主要是对目标server发起ping请求，超时时间为1s，若目标server挂了，则抛出TimeoutException，将目标server加入到downServerCache中；若目标server响应成功，则从downServerCache中移除

小结

PowerJob的worker在初始化的时候会启动一个定时任务，每隔10s调度执行discovery()来更新当前worker的server地址；discovery方法就是定时遍历配置的serverAddress地址列表，调用server端的acquire方法来获取可用的server；ServerController提供了acquire接口，它执行的是serverElectionService.elect(request)，ServerElectionService的elect方法主要是执行getServer0，getServer0方法会重试10次，它先针对discoveryRequest指定的currentServer进行activeAddress，成功则返回，没有可用server则加锁进行重新分配，这里优先本机判断。activeAddress方法主要是对目标server发起ping请求，超时时间为1s，若目标server挂了，则抛出TimeoutException，将目标server加入到downServerCache中；若目标server响应成功，则从downServerCache中移除。

worker定时任务 --> 轮询serverAddress请求acquire --> server端判断目标server的ping是否成功，不成功则加锁优先使用本机作为替代server。