一、Action触发Job, 任务提交的开始从Action开始
/** Submits stage, but first recursively submits any missing parents. */ private def submitStage(stage: Stage) { val jobId = activeJobForStage(stage) if (jobId.isDefined) { logDebug("submitStage(" + stage + ")") if (!waitingStages(stage) && !runningStages(stage) && !failedStages(stage)) { val missing = getMissingParentStages(stage).sortBy(_.id) logDebug("missing: " + missing) if (missing.isEmpty) { logInfo("Submitting " + stage + " (" + stage.rdd + "), which has no missing parents") submitMissingTasks(stage, jobId.get) } else { for (parent <- missing) { submitStage(parent) } waitingStages += stage } } } else { abortStage(stage, "No active job for stage " + stage.id, None) } }