Azkaban的Exec Server分析 31：FlowRunner如何推动Graph的前进

现在，我们知道一个job的执行过程，那么整个flow是一个图，图是如何推进的，如何推进下一个job的执行呢？这就是本节需要解决的问题！

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jdb azkaban.execapp.AzkabanExecutorServer

-conf  /root/azkb/azkaban_3.

0

.0_debug/conf

stop in azkaban.execapp.FlowRunner.progressGraph

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这个用图的算法就可以解决，下面研究下flow的结束部分

stop in azkaban.execapp.FlowRunner.finishExecutableNode

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azkaban.execapp.FlowRunnerManager --- flow的listener

@Override

public void handleEvent(Event event) {

if (event.getType() == Event.Type.FLOW_FINISHED) {

FlowRunner flowRunner = (FlowRunner) event.getRunner();

ExecutableFlow flow = flowRunner.getExecutableFlow();

recentlyFinishedFlows.put(flow.getExecutionId(), flow);

logger.info("Flow " + flow.getExecutionId() + " is finished. Adding it to recently finished flows list.");

runningFlows.remove(flow.getExecutionId());

}

}

这个很简单！
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那么，问题来了，一个Flow如何结束呢？ 收尾工作要做好！

if (outNodeIds.isEmpty()) {

//

// There's no outnodes means it's the end of a flow, so we

// finalize

// and fire an event.

finalizeFlow(parentFlow);

然后这个函数里，

// If the finalized flow is actually the top level flow, than we finish

// the main loop.

if (flow instanceof ExecutableFlow) {

flowFinished = true;

}

这样就设置了flowFinished = true;

=================================================================跳出for循环

private void runFlow() throws Exception {

logger.info("Starting flows");

runReadyJob(this.flow);

updateFlow();

// 跳出这个循环

while (!flowFinished) {

===跳出来之后，执行

logger.info("Finishing up flow. Awaiting Termination");

executorService.shutdown();

updateFlow();

logger.info("Finished Flow");

关闭当前的进程，整个flowRunner这个task就结束了，顺利！