不急,循序渐进,先打好基础
Spark shell的原理
首先,我们清晰定位找到这几个。
1、spark-shell
2、 spark-submit
3、spark-class
4、SparkSubmit.scala
5、SparkILoop.scala
initializeSpark的源码
def initializeSpark() {
intp.beQuietDuring {
command("""
@transient val sc = {
val _sc = org.apache.spark.repl.Main.interp.createSparkContext()
println("Spark context available as sc.")
_sc
}
""")
command("""
@transient val sqlContext = {
val _sqlContext = org.apache.spark.repl.Main.interp.createSQLContext()
println("SQL context available as sqlContext.")
_sqlContext
}
""")
command("import org.apache.spark.SparkContext._")
command("import sqlContext.implicits._")
command("import sqlContext.sql")
command("import org.apache.spark.sql.functions._")
}
createSparkContext的源码
// NOTE: Must be public for visibility
@DeveloperApi
def createSparkContext(): SparkContext = {
val execUri = System.getenv("SPARK_EXECUTOR_URI")
val jars = SparkILoop.getAddedJars
val conf = new SparkConf()
.setMaster(getMaster())
.setAppName("Spark shell")
.setJars(jars)
.set("spark.repl.class.uri", intp.classServerUri)
if (execUri != null) {
conf.set("spark.executor.uri", execUri)
}
sparkContext = new SparkContext(conf)
logInfo("Created spark context..")
sparkContext
}
总结