聊聊PowerJob Worker的ServerAddress

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本文主要研究一下PowerJob Worker的ServerAddress

PowerJobAutoConfiguration

tech/powerjob/worker/autoconfigure/PowerJobAutoConfiguration.java

    @Bean
    @ConditionalOnMissingBean
    public PowerJobSpringWorker initPowerJob(PowerJobProperties properties) {

        PowerJobProperties.Worker worker = properties.getWorker();

        /*
         * Address of PowerJob-server node(s). Do not mistake for ActorSystem port. Do not add
         * any prefix, i.e. http://.
         */
        CommonUtils.requireNonNull(worker.getServerAddress(), "serverAddress can't be empty! " +
            "if you don't want to enable powerjob, please config program arguments: powerjob.worker.enabled=false");
        List serverAddress = Arrays.asList(worker.getServerAddress().split(","));

        /*
         * Create OhMyConfig object for setting properties.
         */
        PowerJobWorkerConfig config = new PowerJobWorkerConfig();
        /*
         * Configuration of worker port. Random port is enabled when port is set with non-positive number.
         */
        if (worker.getPort() != null) {
            config.setPort(worker.getPort());
        } else {
            int port = worker.getAkkaPort();
            if (port <= 0) {
                port = NetUtils.getRandomPort();
            }
            config.setPort(port);
        }
        /*
         * appName, name of the application. Applications should be registered in advance to prevent
         * error. This property should be the same with what you entered for appName when getting
         * registered.
         */
        config.setAppName(worker.getAppName());
        config.setServerAddress(serverAddress);
        config.setProtocol(worker.getProtocol());
        /*
         * For non-Map/MapReduce tasks, {@code memory} is recommended for speeding up calculation.
         * Map/MapReduce tasks may produce batches of subtasks, which could lead to OutOfMemory
         * exception or error, {@code disk} should be applied.
         */
        config.setStoreStrategy(worker.getStoreStrategy());
        /*
         * When enabledTestMode is set as true, PowerJob-worker no longer connects to PowerJob-server
         * or validate appName.
         */
        config.setAllowLazyConnectServer(worker.isAllowLazyConnectServer());
        /*
         * Max length of appended workflow context . Appended workflow context value that is longer than the value will be ignored.
         */
        config.setMaxAppendedWfContextLength(worker.getMaxAppendedWfContextLength());

        config.setTag(worker.getTag());

        config.setMaxHeavyweightTaskNum(worker.getMaxHeavyweightTaskNum());

        config.setMaxLightweightTaskNum(worker.getMaxLightweightTaskNum());

        config.setHealthReportInterval(worker.getHealthReportInterval());
        /*
         * Create PowerJobSpringWorker object and set properties.
         */
        return new PowerJobSpringWorker(config);
    }

PowerJobAutoConfiguration读取powerjob.worker.server-address属性，解析逗号分隔，赋值给PowerJobWorkerConfig的serverAddress

PowerJobServerDiscoveryService

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

    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 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;
        }
    }

PowerJobServerDiscoveryService的discovery会遍历config.getServerAddress()，执行acquire(httpServerAddress)，请求服务端获取该appName所负责的server地址，若获取不到则继续循环

小结

PowerJob的worker需要配置powerjob.worker.server-address属性，它可以配置多个地址和port，但是默认请求discovery的时候是按顺序遍历下来，这个后续可以优化为随机。另外请求server端获取该appName的currentServer的时候，也在一定程度上依赖了本机地址去负责该请求的worker，这个也是跟配置顺序有关系。官方是建议配置域名，通过域名负载均衡，或者是给不同app配置地址的时候，多个地址给随机化配置，不要按固定顺序。