SparkSession

The entry point to programming Spark with the Dataset and DataFrame API.

In environments that this has been created upfront (e.g. REPL, notebooks), use the builder
to get an existing session:

SparkSession.builder().getOrCreate()

The builder can also be used to create a new session:

SparkSession.builder
      .master("local")
      .appName("Word Count")
      .config("spark.some.config.option", "some-value")
      .getOrCreate()

SparkSession 是 Spark SQL 的入口。

def getOrCreate(): SparkSession = synchronized {

// Get the session from current thread's active session.
      var session = activeThreadSession.get()
      if ((session ne null) && !session.sparkContext.isStopped) {
        op