聊聊PowerJob的BroadcastProcessor

序

本文主要研究一下PowerJob的BroadcastProcessor

BroadcastProcessor

tech/powerjob/worker/core/processor/sdk/BroadcastProcessor.java

public interface BroadcastProcessor extends BasicProcessor {

    /**
     * 在所有节点广播执行前执行，只会在一台机器执行一次
     */
    default ProcessResult preProcess(TaskContext context) throws Exception {
        return new ProcessResult(true);
    }
    /**
     * 在所有节点广播执行完成后执行，只会在一台机器执行一次
     */
    default ProcessResult postProcess(TaskContext context, List taskResults) throws Exception {
        return defaultResult(taskResults);
    }

    static ProcessResult defaultResult(List taskResults) {
        long succeed = 0, failed = 0;
        for (TaskResult ts : taskResults) {
            if (ts.isSuccess()) {
                succeed ++ ;
            }else {
                failed ++;
            }
        }
        return new ProcessResult(failed == 0, String.format("succeed:%d, failed:%d", succeed, failed));
    }
}

BroadcastProcessor接口继承了BasicProcessor，它定义了preProcess、postProcess、defaultResult方法，其中preProcess默认返回成功的ProcessResult，postProcess返回defaultResult，它会根据taskResults计算最终的success与否

HeavyProcessorRunnable

tech/powerjob/worker/core/processor/runnable/HeavyProcessorRunnable.java

public class HeavyProcessorRunnable implements Runnable {


    private final InstanceInfo instanceInfo;
    private final String taskTrackerAddress;
    private final TaskDO task;
    private final ProcessorBean processorBean;
    private final OmsLogger omsLogger;
    /**
     * 重试队列，ProcessorTracker 将会定期重新上报处理结果
     */
    private final Queue statusReportRetryQueue;
    private final WorkerRuntime workerRuntime;

    @Override
    @SuppressWarnings("squid:S2142")
    public void run() {
        // 切换线程上下文类加载器（否则用的是 Worker 类加载器，不存在容器类，在序列化/反序列化时会报 ClassNotFoundException）
        Thread.currentThread().setContextClassLoader(processorBean.getClassLoader());
        try {
            innerRun();
        } catch (InterruptedException ignore) {
            // ignore
        } catch (Throwable e) {
            reportStatus(TaskStatus.WORKER_PROCESS_FAILED, e.toString(), null, null);
            log.error("[ProcessorRunnable-{}] execute failed, please contact the author(@KFCFans) to fix the bug!", task.getInstanceId(), e);
        } finally {
            ThreadLocalStore.clear();
        }
    }    

    public void innerRun() throws InterruptedException {

        final BasicProcessor processor = processorBean.getProcessor();

        String taskId = task.getTaskId();
        Long instanceId = task.getInstanceId();

        log.debug("[ProcessorRunnable-{}] start to run task(taskId={}&taskName={})", instanceId, taskId, task.getTaskName());
        ThreadLocalStore.setTask(task);
        ThreadLocalStore.setRuntimeMeta(workerRuntime);

        // 0. 构造任务上下文
        WorkflowContext workflowContext = constructWorkflowContext();
        TaskContext taskContext = constructTaskContext();
        taskContext.setWorkflowContext(workflowContext);
        // 1. 上报执行信息
        reportStatus(TaskStatus.WORKER_PROCESSING, null, null, null);

        ProcessResult processResult;
        ExecuteType executeType = ExecuteType.valueOf(instanceInfo.getExecuteType());

        // 2. 根任务 & 广播执行 特殊处理
        if (TaskConstant.ROOT_TASK_NAME.equals(task.getTaskName()) && executeType == ExecuteType.BROADCAST) {
            // 广播执行：先选本机执行 preProcess，完成后 TaskTracker 再为所有 Worker 生成子 Task
            handleBroadcastRootTask(instanceId, taskContext);
            return;
        }

        // 3. 最终任务特殊处理（一定和 TaskTracker 处于相同的机器）
        if (TaskConstant.LAST_TASK_NAME.equals(task.getTaskName())) {
            handleLastTask(taskId, instanceId, taskContext, executeType);
            return;
        }

        // 4. 正式提交运行
        try {
            processResult = processor.process(taskContext);
            if (processResult == null) {
                processResult = new ProcessResult(false, "ProcessResult can't be null");
            }
        } catch (Throwable e) {
            log.warn("[ProcessorRunnable-{}] task(id={},name={}) process failed.", instanceId, taskContext.getTaskId(), taskContext.getTaskName(), e);
            processResult = new ProcessResult(false, e.toString());
        }
        reportStatus(processResult.isSuccess() ? TaskStatus.WORKER_PROCESS_SUCCESS : TaskStatus.WORKER_PROCESS_FAILED, suit(processResult.getMsg()), null, workflowContext.getAppendedContextData());
    }

    //......
}    

HeavyProcessorRunnable实现了Runnable接口，其run方法设置Thread.currentThread().setContextClassLoader为processorBean.getClassLoader()，然后执行innerRun，它对于BROADCAST的root任务会执行handleBroadcastRootTask，对于last任务执行handleLastTask，否则执行processor.process(taskContext)，最后执行reportStatus

handleBroadcastRootTask

    private void handleBroadcastRootTask(Long instanceId, TaskContext taskContext) {
        BasicProcessor processor = processorBean.getProcessor();
        ProcessResult processResult;
        // 广播执行的第一个 task 只执行 preProcess 部分
        if (processor instanceof BroadcastProcessor) {

            BroadcastProcessor broadcastProcessor = (BroadcastProcessor) processor;
            try {
                processResult = broadcastProcessor.preProcess(taskContext);
            } catch (Throwable e) {
                log.warn("[ProcessorRunnable-{}] broadcast task preProcess failed.", instanceId, e);
                processResult = new ProcessResult(false, e.toString());
            }

        } else {
            processResult = new ProcessResult(true, "NO_PREPOST_TASK");
        }
        // 通知 TaskTracker 创建广播子任务
        reportStatus(processResult.isSuccess() ? TaskStatus.WORKER_PROCESS_SUCCESS : TaskStatus.WORKER_PROCESS_FAILED, suit(processResult.getMsg()), ProcessorReportTaskStatusReq.BROADCAST, taskContext.getWorkflowContext().getAppendedContextData());

    }

handleBroadcastRootTask方法执行broadcastProcessor.preProcess(taskContext)，然后reportStatus，其cmd为ProcessorReportTaskStatusReq.BROADCAST

handleLastTask

    private void handleLastTask(String taskId, Long instanceId, TaskContext taskContext, ExecuteType executeType) {
        final BasicProcessor processor = processorBean.getProcessor();
        ProcessResult processResult;
        Stopwatch stopwatch = Stopwatch.createStarted();
        log.debug("[ProcessorRunnable-{}] the last task(taskId={}) start to process.", instanceId, taskId);

        List taskResults = workerRuntime.getTaskPersistenceService().getAllTaskResult(instanceId, task.getSubInstanceId());
        try {
            switch (executeType) {
                case BROADCAST:

                    if (processor instanceof BroadcastProcessor) {
                        BroadcastProcessor broadcastProcessor = (BroadcastProcessor) processor;
                        processResult = broadcastProcessor.postProcess(taskContext, taskResults);
                    } else {
                        processResult = BroadcastProcessor.defaultResult(taskResults);
                    }
                    break;
                case MAP_REDUCE:

                    if (processor instanceof MapReduceProcessor) {
                        MapReduceProcessor mapReduceProcessor = (MapReduceProcessor) processor;
                        processResult = mapReduceProcessor.reduce(taskContext, taskResults);
                    } else {
                        processResult = new ProcessResult(false, "not implement the MapReduceProcessor");
                    }
                    break;
                default:
                    processResult = new ProcessResult(false, "IMPOSSIBLE OR BUG");
            }
        } catch (Throwable e) {
            processResult = new ProcessResult(false, e.toString());
            log.warn("[ProcessorRunnable-{}] execute last task(taskId={}) failed.", instanceId, taskId, e);
        }

        TaskStatus status = processResult.isSuccess() ? TaskStatus.WORKER_PROCESS_SUCCESS : TaskStatus.WORKER_PROCESS_FAILED;
        reportStatus(status, suit(processResult.getMsg()), null, taskContext.getWorkflowContext().getAppendedContextData());

        log.info("[ProcessorRunnable-{}] the last task execute successfully, using time: {}", instanceId, stopwatch);
    }

handleLastTask对于BROADCAST则执行broadcastProcessor.postProcess或者BroadcastProcessor.defaultResult

reportStatus

    private void reportStatus(TaskStatus status, String result, Integer cmd, Map appendedWfContext) {
        ProcessorReportTaskStatusReq req = new ProcessorReportTaskStatusReq();

        req.setInstanceId(task.getInstanceId());
        req.setSubInstanceId(task.getSubInstanceId());
        req.setTaskId(task.getTaskId());
        req.setStatus(status.getValue());
        req.setResult(result);
        req.setReportTime(System.currentTimeMillis());
        req.setCmd(cmd);
        // 检查追加的上下文大小是否超出限制
        if (instanceInfo.getWfInstanceId() !=null && WorkflowContextUtils.isExceededLengthLimit(appendedWfContext, workerRuntime.getWorkerConfig().getMaxAppendedWfContextLength())) {
            log.warn("[ProcessorRunnable-{}]current length of appended workflow context data is greater than {}, this appended workflow context data will be ignore!",instanceInfo.getInstanceId(), workerRuntime.getWorkerConfig().getMaxAppendedWfContextLength());
            // ignore appended workflow context data
            appendedWfContext = Collections.emptyMap();
        }
        req.setAppendedWfContext(appendedWfContext);

        // 最终结束状态要求可靠发送
        if (TaskStatus.FINISHED_STATUS.contains(status.getValue())) {
            boolean success = TransportUtils.reliablePtReportTask(req, taskTrackerAddress, workerRuntime);
            if (!success) {
                // 插入重试队列，等待重试
                statusReportRetryQueue.add(req);
                log.warn("[ProcessorRunnable-{}] report task(id={},status={},result={}) failed, will retry later", task.getInstanceId(), task.getTaskId(), status, result);
            }
        } else {
            TransportUtils.ptReportTask(req, taskTrackerAddress, workerRuntime);
        }
    }

reportStatus上报状态给TaskTracker，它构建ProcessorReportTaskStatusReq，对于FINISHED_STATUS的执行TransportUtils.reliablePtReportTask，失败则进入重试队列，否则执行TransportUtils.ptReportTask

TransportUtils

tech/powerjob/worker/common/utils/TransportUtils.java

    public static boolean reliablePtReportTask(ProcessorReportTaskStatusReq req, String address, WorkerRuntime workerRuntime) {
        try {
            return reliableAsk(ServerType.WORKER, WTT_PATH, WTT_HANDLER_REPORT_TASK_STATUS, address, req, workerRuntime.getTransporter()).isSuccess();
        } catch (Exception e) {
            log.warn("[PowerJobTransport] reliablePtReportTask failed: {}", req, e);
            return false;
        }
    }

    private static AskResponse reliableAsk(ServerType t, String rootPath, String handlerPath, String address, PowerSerializable req, Transporter transporter) throws Exception {
        final URL url = easyBuildUrl(t, rootPath, handlerPath, address);
        final CompletionStage completionStage = transporter.ask(url, req, AskResponse.class);
        return completionStage
                .toCompletableFuture()
                .get(RemoteConstant.DEFAULT_TIMEOUT_MS, TimeUnit.MILLISECONDS);
    }    

    public static void ptReportTask(ProcessorReportTaskStatusReq req, String address, WorkerRuntime workerRuntime) {
        final URL url = easyBuildUrl(ServerType.WORKER, WTT_PATH, WTT_HANDLER_REPORT_TASK_STATUS, address);
        workerRuntime.getTransporter().tell(url, req);
    }    

reliablePtReportTask用的是ask方法，ptReportTask用的是tell方法

onReceiveProcessorReportTaskStatusReq

tech/powerjob/worker/actors/TaskTrackerActor.java

    @Handler(path = WTT_HANDLER_REPORT_TASK_STATUS)
    public AskResponse onReceiveProcessorReportTaskStatusReq(ProcessorReportTaskStatusReq req) {

        int taskStatus = req.getStatus();
        // 只有重量级任务才会有两级任务状态上报的机制
        HeavyTaskTracker taskTracker = HeavyTaskTrackerManager.getTaskTracker(req.getInstanceId());

        // 手动停止 TaskTracker 的情况下会出现这种情况
        if (taskTracker == null) {
            log.warn("[TaskTrackerActor] receive ProcessorReportTaskStatusReq({}) but system can't find TaskTracker.", req);
            return null;
        }

        if (ProcessorReportTaskStatusReq.BROADCAST.equals(req.getCmd())) {
            taskTracker.broadcast(taskStatus == TaskStatus.WORKER_PROCESS_SUCCESS.getValue(), req.getSubInstanceId(), req.getTaskId(), req.getResult());
        }

        taskTracker.updateTaskStatus(req.getSubInstanceId(), req.getTaskId(), taskStatus, req.getReportTime(), req.getResult());

        // 更新工作流上下文
        taskTracker.updateAppendedWfContext(req.getAppendedWfContext());

        // 结束状态需要回复接受成功
        if (TaskStatus.FINISHED_STATUS.contains(taskStatus)) {
            return AskResponse.succeed(null);
        }

        return null;
    }

TaskTrackerActor的onReceiveProcessorReportTaskStatusReq用于处理ProcessorReportTaskStatusReq，它针对cmd为BROADCAST的执行taskTracker.broadcast

broadcast

tech/powerjob/worker/core/tracker/task/heavy/HeavyTaskTracker.java

    public void broadcast(boolean preExecuteSuccess, long subInstanceId, String preTaskId, String result) {

        if (finished.get()) {
            return;
        }

        log.info("[TaskTracker-{}-{}] finished broadcast's preProcess, preExecuteSuccess:{},preTaskId:{},result:{}", instanceId, subInstanceId, preExecuteSuccess, preTaskId, result);

        // 生成集群子任务
        if (preExecuteSuccess) {
            List allWorkerAddress = ptStatusHolder.getAllProcessorTrackers();
            List subTaskList = Lists.newLinkedList();
            for (int i = 0; i < allWorkerAddress.size(); i++) {
                TaskDO subTask = new TaskDO();
                subTask.setSubInstanceId(subInstanceId);
                subTask.setTaskName(TaskConstant.BROADCAST_TASK_NAME);
                subTask.setTaskId(preTaskId + "." + i);
                // 广播任务直接写入派发地址
                subTask.setAddress(allWorkerAddress.get(i));
                subTaskList.add(subTask);
            }
            submitTask(subTaskList);
        } else {
            log.warn("[TaskTracker-{}-{}] BroadcastTask failed because of preProcess failed, preProcess result={}.", instanceId, subInstanceId, result);
        }
    }

    public boolean submitTask(List newTaskList) {
        if (finished.get()) {
            return true;
        }
        if (CollectionUtils.isEmpty(newTaskList)) {
            return true;
        }
        // 基础处理（多循环一次虽然有些浪费，但分布式执行中，这点耗时绝不是主要占比，忽略不计！）
        newTaskList.forEach(task -> {
            task.setInstanceId(instanceId);
            task.setStatus(TaskStatus.WAITING_DISPATCH.getValue());
            task.setFailedCnt(0);
            task.setLastModifiedTime(System.currentTimeMillis());
            task.setCreatedTime(System.currentTimeMillis());
            task.setLastReportTime(-1L);
        });

        log.debug("[TaskTracker-{}] receive new tasks: {}", instanceId, newTaskList);
        return taskPersistenceService.batchSave(newTaskList);
    }    

HeavyTaskTracker的broadcast方法会通过ptStatusHolder.getAllProcessorTrackers()获取allWorkerAddress，然后遍历allWorkerAddress，挨个生成subTask，最后提交这一批subTaskList；submitTask通过taskPersistenceService.batchSave进行保存

小结

• BroadcastProcessor接口继承了BasicProcessor，它定义了preProcess、postProcess、defaultResult方法，其中preProcess默认返回成功的ProcessResult，postProcess返回defaultResult，它会根据taskResults计算最终的success与否；
• HeavyProcessorRunnable实现了Runnable接口，其run方法设置Thread.currentThread().setContextClassLoader为processorBean.getClassLoader()，然后执行innerRun，它对于BROADCAST的root任务会执行handleBroadcastRootTask，对于last任务执行handleLastTask，否则执行processor.process(taskContext)，最后执行reportStatus
• handleBroadcastRootTask方法执行broadcastProcessor.preProcess(taskContext)，然后reportStatus，其cmd为ProcessorReportTaskStatusReq.BROADCAST
• handleLastTask对于BROADCAST则执行broadcastProcessor.postProcess或者BroadcastProcessor.defaultResult
• HeavyTaskTracker的broadcast方法会通过ptStatusHolder.getAllProcessorTrackers()获取allWorkerAddress，然后遍历allWorkerAddress，挨个生成subTask，最后提交这一批subTaskList；submitTask通过taskPersistenceService.batchSave进行保存