目錄
Spark:一個獨立應用
關於構建
Java和Scala
在Java和Scala中,只需要給你的應用添加一個對於spark-core的Maven依賴.
Python
在Python中,可以把應用寫成腳本,然后使用Spark自帶的bin/spark-submit腳本來運行.spark-submit會引入Python程序的Spark依賴.使用方式如下所示.
/PATH_TO_SPARK/bin/spark-submit my_python_script.py
初始化SparkContext
- 先創建一個
SparkConf對象來配置應用 - 基於
SparkConf創建一個SparkContext對象
Python示例
代碼
from pyspark import SparkConf, SparkContext
conf = SparkConf().setMaster("local").setAppName("My App")
sc = SparkContext(conf = conf)
運行
spark-submit spark-app.py
Scala示例
import org.apache.spark.SparkConf
import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
val conf = new SparkConf().setMaster("local").setAppName("My App")
val sc = new SparkContext(conf)
Java示例
import org.apache.spark.SparkConf
import org.apache.spark.api.java.JavaSparkContext
SparkConf conf = new SparkConf().setMaster("local").setAppName("My App");
JavaSparkContext sc = new JavaSparkContext(conf);
說明
上述例子是創建SparkContext的最基本的方法,你只需傳遞兩個參數:
- 集群URL(上述是local),告訴Spark如何運行連接到集群上
- 應用名可以用來在集群管理器的用戶界面找到該應用
獨立應用示例
創建空白目錄,在新建目錄下,新建文件simpleApp.Scala,添加如下代碼.
Scala代碼
import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark.SparkConf
object SimpleApp {
def main(args: Array[String]) {
val logFile = "README.md"
val conf = new SparkConf().setAppName("Simple Application")
val sc = new SparkContext(conf)
val logData = sc.textFile(logFile, 2).cache()
val numAs = logData.filter(line => line.contains("a")).count()
val numBs = logData.filter(line => line.contains("b")).count()
println("Lines with a: %s, lines with b: %s".format(numAs, numBs))
}
}
構建文件
在新建目錄下,新建文件simple.sbt,復制如下代碼.
name := "Simple Application"
version := "1.0"
scalaVersion := "2.11.8"
libraryDependencies += "org.apache.spark" %% "spark-core" % "2.0.0"
- 使用
scala -version命令查看scala版本,使用spark-shell可以查看spark版本及scala版本,使用:quit命令退出spark-shell
說明
- 程序構建需要安裝sbt
- 程序用來統計
README.md文件中包含a和b的行數 - 需要將
README.md放到Spark使用的文件系統的相應位置.比如,如果使用的是HDFS,README.md應該放在/user/YOUR_USER_NAME/目錄下, 或者將val logFile = "README.md"中的文件路徑改為絕對路徑,例如:val logFile = "/user/mint/README.md".
構建
新建文件夾下包含的文件
$ ls
simpleApp.scala simple.sbt
執行構建
$ sbt package
[info] Set current project to Simple Project (in build file:/home/public/program/scala/self-cont-app/)
[info] Updating {file:/home/public/program/scala/self-cont-app/}self-cont-app...
[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.
[info] Compiling 1 Scala source to /home/public/program/scala/self-cont-app/target/scala-2.11/classes...
[info] Packaging /home/public/program/scala/self-cont-app/target/scala-2.11/simple-project_2.11-1.0.jar ...
[info] Done packaging.
[success] Total time: 11 s, completed Sep 8, 2016 3:12:31 PM
運行構建的程序
$ spark-submit --class "SimpleApp" --master local[4] ./target/scala-2.11/simple-project_2.11-1.0.jar
SLF4J: Class path contains multiple SLF4J bindings.
...
Lines with a: 61, lines with b: 27