学习作业启动

yarn/job_start.md

@@ -288,6 +288,22 @@ protected void handleJobSetup(CommitterJobSetupEvent event) {
 }
 ```
 
+SetupCompletedTransition的处理逻辑如下，可以看到会定时启动MapTask和ReduceTask。
+
+```java
+public void transition(JobImpl job, JobEvent event) {
+  job.setupProgress = 1.0f;
+  job.scheduleTasks(job.mapTasks, job.numReduceTasks == 0);
+  job.scheduleTasks(job.reduceTasks, true);
+
+  // If we have no tasks, just transition to job completed
+  if (job.numReduceTasks == 0 && job.numMapTasks == 0) {
+    job.eventHandler.handle(new JobEvent(job.jobId,
+        JobEventType.JOB_COMPLETED));
+  }
+}
+```
+
 checkReadyForCommit函数的实现如下，可以看到在触发了CommitterJobCommitEvent事件,在CommitterJobCommitEvent里面会触发JOB_COMMIT事件。主要处理逻辑在handleJobCommit里面。
 
 ```java
@@ -344,3 +360,14 @@ protected void handleJobCommit(CommitterJobCommitEvent event) {
   }
 }
 ```
+
+
+
+##### CommitSucceededTransition
+
+提交成功的事件处理handler为CommitSucceededTransition，核心处理逻辑如下：
+
+```java
+job.logJobHistoryFinishedEvent();
+job.finished(JobStateInternal.SUCCEEDED);
+```