Spark Core Runtime分析: DAGScheduler, TaskScheduler, SchedulerBackend
SparkRuntime里的主要层次分析,梳理Runtime组件和执行流程,DAGSchedulerJob=多个stage,Stage=多个同种task,Task分为ShuffleMapTask和ResultTask,Dependency分为ShuffleDependency和NarrowDependency面向stage的切分,切分依据为宽依赖维护waitingjobs和activejobs,维