scala> val rdd1 = sc.parallelize(List(5,6,4,7,3,8,2,9,1,10))
rdd1: org.apache.spark.rdd.RDD[Int] = ParallelCollectionRDD[0] at parallelize at <console>:24
scala> rdd1.id
res4: Int = 0
就是個id，沒啥用
參考:
https://stackoverflow.com/questions/48277531/what-does-the-number-meaning-after-the-rdd