在 IntelliJ 中运行 Spark Word Count

Question

I've spent hours going through You Tube vids and tutorials trying to understand how I run a run a word count program for Spark, in Scala, and the turn it into a jar file. I'm getting utterly confused now.

I got Hello World running, and I've learn about going to the libraries to add in Apache.spark.spark-core, but now I'm getting

Error: Could not find or load main class WordCount

Further more I'm utterly bewildered why these two tutorials which I thought we teaching the same thing seem to differ so much: tutorial1 tutorial2

The second one seems to be twice as long as the first and it throws in things that the first didn't mention. Should I be relying on either of these to help me get a simple word count program and jar up and running?

Ps. My code currently looks like this. I copied it from somewhere:

import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark._

object WordCount {
  def main(args: Array[String]) {

    val sc = new SparkContext( "local", "Word Count", "/usr/local/spark", Nil, Map(), Map())
    val input = sc.textFile("../Data/input.txt")
    val count = input.flatMap(line ⇒ line.split(" "))
      .map(word ⇒ (word, 1))
      .reduceByKey(_ + _)
    count.saveAsTextFile("outfile")
    System.out.println("OK");
  }
}

Answer 1

In IntelliJ Idea do File -> New -> Project -> Scala -> SBT -> (select location and name for project) -> Finish.

Write in build.sbt

scalaVersion := "2.11.11"
libraryDependencies += "org.apache.spark" % "spark-core_2.11" % "2.2.0"

Do sbt update in command line (from within your main project folder) or press refresh button in SBT Tool window inside IntelliJ Idea).

Write your code in src/main/scala/WordCount.scala

import org.apache.spark.{SparkConf, SparkContext}

object WordCount {
  def main(args: Array[String]) {
    val conf = new SparkConf()
      .setMaster("local")
      .setAppName("Word Count")
      .setSparkHome("src/main/resources")
    val sc = new SparkContext(conf)
    val input = sc.textFile("src/main/resources/input.txt")
    val count = input.flatMap(line ⇒ line.split(" "))
      .map(word ⇒ (word, 1))
      .reduceByKey(_ + _)
    count.saveAsTextFile("src/main/resources/outfile")
    println("OK")
  }
}

Put your file as src/main/resources/input.txt

Run your code: Ctrl+Shift+F10 or sbt run

In folder src/main/resources there should appear new subfolder outfile with several files.

Console output:

Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
17/09/02 14:57:08 INFO SparkContext: Running Spark version 2.2.0
17/09/02 14:57:09 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
17/09/02 14:57:09 WARN Utils: Your hostname, dmitin-HP-Pavilion-Notebook resolves to a loopback address: 127.0.1.1; using 192.168.1.104 instead (on interface wlan0)
17/09/02 14:57:09 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
17/09/02 14:57:09 INFO SparkContext: Submitted application: Word Count
17/09/02 14:57:09 INFO SecurityManager: Changing view acls to: dmitin
17/09/02 14:57:09 INFO SecurityManager: Changing modify acls to: dmitin
17/09/02 14:57:09 INFO SecurityManager: Changing view acls groups to: 
17/09/02 14:57:09 INFO SecurityManager: Changing modify acls groups to: 
17/09/02 14:57:09 INFO SecurityManager: SecurityManager: authentication disabled; ui acls disabled; users  with view permissions: Set(dmitin); groups with view permissions: Set(); users  with modify permissions: Set(dmitin); groups with modify permissions: Set()
17/09/02 14:57:10 INFO Utils: Successfully started service 'sparkDriver' on port 38186.
17/09/02 14:57:10 INFO SparkEnv: Registering MapOutputTracker
17/09/02 14:57:10 INFO SparkEnv: Registering BlockManagerMaster
17/09/02 14:57:10 INFO BlockManagerMasterEndpoint: Using org.apache.spark.storage.DefaultTopologyMapper for getting topology information
17/09/02 14:57:10 INFO BlockManagerMasterEndpoint: BlockManagerMasterEndpoint up
17/09/02 14:57:10 INFO DiskBlockManager: Created local directory at /tmp/blockmgr-d90a4735-6a2b-42b2-85ea-55b0ed9b1dfd
17/09/02 14:57:10 INFO MemoryStore: MemoryStore started with capacity 1950.3 MB
17/09/02 14:57:10 INFO SparkEnv: Registering OutputCommitCoordinator
17/09/02 14:57:10 INFO Utils: Successfully started service 'SparkUI' on port 4040.
17/09/02 14:57:11 INFO SparkUI: Bound SparkUI to 0.0.0.0, and started at http://192.168.1.104:4040
17/09/02 14:57:11 INFO Executor: Starting executor ID driver on host localhost
17/09/02 14:57:11 INFO Utils: Successfully started service 'org.apache.spark.network.netty.NettyBlockTransferService' on port 46432.
17/09/02 14:57:11 INFO NettyBlockTransferService: Server created on 192.168.1.104:46432
17/09/02 14:57:11 INFO BlockManager: Using org.apache.spark.storage.RandomBlockReplicationPolicy for block replication policy
17/09/02 14:57:11 INFO BlockManagerMaster: Registering BlockManager BlockManagerId(driver, 192.168.1.104, 46432, None)
17/09/02 14:57:11 INFO BlockManagerMasterEndpoint: Registering block manager 192.168.1.104:46432 with 1950.3 MB RAM, BlockManagerId(driver, 192.168.1.104, 46432, None)
17/09/02 14:57:11 INFO BlockManagerMaster: Registered BlockManager BlockManagerId(driver, 192.168.1.104, 46432, None)
17/09/02 14:57:11 INFO BlockManager: Initialized BlockManager: BlockManagerId(driver, 192.168.1.104, 46432, None)
17/09/02 14:57:12 INFO MemoryStore: Block broadcast_0 stored as values in memory (estimated size 214.5 KB, free 1950.1 MB)
17/09/02 14:57:12 INFO MemoryStore: Block broadcast_0_piece0 stored as bytes in memory (estimated size 20.4 KB, free 1950.1 MB)
17/09/02 14:57:12 INFO BlockManagerInfo: Added broadcast_0_piece0 in memory on 192.168.1.104:46432 (size: 20.4 KB, free: 1950.3 MB)
17/09/02 14:57:12 INFO SparkContext: Created broadcast 0 from textFile at WordCount.scala:16
17/09/02 14:57:12 INFO FileInputFormat: Total input paths to process : 1
17/09/02 14:57:12 INFO SparkContext: Starting job: saveAsTextFile at WordCount.scala:20
17/09/02 14:57:12 INFO DAGScheduler: Registering RDD 3 (map at WordCount.scala:18)
17/09/02 14:57:12 INFO DAGScheduler: Got job 0 (saveAsTextFile at WordCount.scala:20) with 1 output partitions
17/09/02 14:57:12 INFO DAGScheduler: Final stage: ResultStage 1 (saveAsTextFile at WordCount.scala:20)
17/09/02 14:57:12 INFO DAGScheduler: Parents of final stage: List(ShuffleMapStage 0)
17/09/02 14:57:12 INFO DAGScheduler: Missing parents: List(ShuffleMapStage 0)
17/09/02 14:57:12 INFO DAGScheduler: Submitting ShuffleMapStage 0 (MapPartitionsRDD[3] at map at WordCount.scala:18), which has no missing parents
17/09/02 14:57:13 INFO MemoryStore: Block broadcast_1 stored as values in memory (estimated size 4.7 KB, free 1950.1 MB)
17/09/02 14:57:13 INFO MemoryStore: Block broadcast_1_piece0 stored as bytes in memory (estimated size 2.7 KB, free 1950.1 MB)
17/09/02 14:57:13 INFO BlockManagerInfo: Added broadcast_1_piece0 in memory on 192.168.1.104:46432 (size: 2.7 KB, free: 1950.3 MB)
17/09/02 14:57:13 INFO SparkContext: Created broadcast 1 from broadcast at DAGScheduler.scala:1006
17/09/02 14:57:13 INFO DAGScheduler: Submitting 1 missing tasks from ShuffleMapStage 0 (MapPartitionsRDD[3] at map at WordCount.scala:18) (first 15 tasks are for partitions Vector(0))
17/09/02 14:57:13 INFO TaskSchedulerImpl: Adding task set 0.0 with 1 tasks
17/09/02 14:57:13 INFO TaskSetManager: Starting task 0.0 in stage 0.0 (TID 0, localhost, executor driver, partition 0, PROCESS_LOCAL, 4873 bytes)
17/09/02 14:57:13 INFO Executor: Running task 0.0 in stage 0.0 (TID 0)
17/09/02 14:57:13 INFO HadoopRDD: Input split: file:/home/dmitin/Projects/sparkdemo/src/main/resources/input.txt:0+11
17/09/02 14:57:13 INFO Executor: Finished task 0.0 in stage 0.0 (TID 0). 1154 bytes result sent to driver
17/09/02 14:57:13 INFO TaskSetManager: Finished task 0.0 in stage 0.0 (TID 0) in 289 ms on localhost (executor driver) (1/1)
17/09/02 14:57:13 INFO DAGScheduler: ShuffleMapStage 0 (map at WordCount.scala:18) finished in 0,321 s
17/09/02 14:57:13 INFO TaskSchedulerImpl: Removed TaskSet 0.0, whose tasks have all completed, from pool 
17/09/02 14:57:13 INFO DAGScheduler: looking for newly runnable stages
17/09/02 14:57:13 INFO DAGScheduler: running: Set()
17/09/02 14:57:13 INFO DAGScheduler: waiting: Set(ResultStage 1)
17/09/02 14:57:13 INFO DAGScheduler: failed: Set()
17/09/02 14:57:13 INFO DAGScheduler: Submitting ResultStage 1 (MapPartitionsRDD[5] at saveAsTextFile at WordCount.scala:20), which has no missing parents
17/09/02 14:57:13 INFO MemoryStore: Block broadcast_2 stored as values in memory (estimated size 65.3 KB, free 1950.0 MB)
17/09/02 14:57:13 INFO MemoryStore: Block broadcast_2_piece0 stored as bytes in memory (estimated size 23.3 KB, free 1950.0 MB)
17/09/02 14:57:13 INFO BlockManagerInfo: Added broadcast_2_piece0 in memory on 192.168.1.104:46432 (size: 23.3 KB, free: 1950.3 MB)
17/09/02 14:57:13 INFO SparkContext: Created broadcast 2 from broadcast at DAGScheduler.scala:1006
17/09/02 14:57:13 INFO DAGScheduler: Submitting 1 missing tasks from ResultStage 1 (MapPartitionsRDD[5] at saveAsTextFile at WordCount.scala:20) (first 15 tasks are for partitions Vector(0))
17/09/02 14:57:13 INFO TaskSchedulerImpl: Adding task set 1.0 with 1 tasks
17/09/02 14:57:13 INFO TaskSetManager: Starting task 0.0 in stage 1.0 (TID 1, localhost, executor driver, partition 0, ANY, 4621 bytes)
17/09/02 14:57:13 INFO Executor: Running task 0.0 in stage 1.0 (TID 1)
17/09/02 14:57:13 INFO ShuffleBlockFetcherIterator: Getting 1 non-empty blocks out of 1 blocks
17/09/02 14:57:13 INFO ShuffleBlockFetcherIterator: Started 0 remote fetches in 10 ms
17/09/02 14:57:13 INFO FileOutputCommitter: Saved output of task 'attempt_20170902145712_0001_m_000000_1' to file:/home/dmitin/Projects/sparkdemo/src/main/resources/outfile/_temporary/0/task_20170902145712_0001_m_000000
17/09/02 14:57:13 INFO SparkHadoopMapRedUtil: attempt_20170902145712_0001_m_000000_1: Committed
17/09/02 14:57:13 INFO Executor: Finished task 0.0 in stage 1.0 (TID 1). 1224 bytes result sent to driver
17/09/02 14:57:13 INFO TaskSetManager: Finished task 0.0 in stage 1.0 (TID 1) in 221 ms on localhost (executor driver) (1/1)
17/09/02 14:57:13 INFO TaskSchedulerImpl: Removed TaskSet 1.0, whose tasks have all completed, from pool 
17/09/02 14:57:13 INFO DAGScheduler: ResultStage 1 (saveAsTextFile at WordCount.scala:20) finished in 0,223 s
17/09/02 14:57:13 INFO DAGScheduler: Job 0 finished: saveAsTextFile at WordCount.scala:20, took 1,222133 s
OK
17/09/02 14:57:13 INFO SparkContext: Invoking stop() from shutdown hook
17/09/02 14:57:13 INFO SparkUI: Stopped Spark web UI at http://192.168.1.104:4040
17/09/02 14:57:13 INFO MapOutputTrackerMasterEndpoint: MapOutputTrackerMasterEndpoint stopped!
17/09/02 14:57:13 INFO MemoryStore: MemoryStore cleared
17/09/02 14:57:13 INFO BlockManager: BlockManager stopped
17/09/02 14:57:13 INFO BlockManagerMaster: BlockManagerMaster stopped
17/09/02 14:57:13 INFO OutputCommitCoordinator$OutputCommitCoordinatorEndpoint: OutputCommitCoordinator stopped!
17/09/02 14:57:13 INFO SparkContext: Successfully stopped SparkContext
17/09/02 14:57:13 INFO ShutdownHookManager: Shutdown hook called
17/09/02 14:57:13 INFO ShutdownHookManager: Deleting directory /tmp/spark-663047b2-415a-45b5-bcad-20bd18270baa

Process finished with exit code 0

Answer 2

You can always do WordCount extends App and this should work. I believe its about the way you have structured your project.

Read more about the app trait here.

http://www.scala-lang.org/api/2.12.1/scala/App.html

In any case, please make sure that your directory layout looks like this.

./build.sbt
./src
./src/main
./src/main/scala
./src/main/scala/WordCount.scala

Answer 3

check the sample code which i written show below

package com.spark.app

import org.scalatra._
import org.apache.spark.{ SparkContext, SparkConf }

class MySparkAppServlet extends MySparkAppStack {

  get("/wc") {
        val inputFile = "/home/limitless/Documents/projects/test/my-spark-app/README.md"
        val outputFile = "/home/limitless/Documents/projects/test/my-spark-app/README.txt"
        val conf = new SparkConf().setAppName("wordCount").setMaster("local[*]")
        val sc = new SparkContext(conf)
        val input =  sc.textFile(inputFile)
        val words = input.flatMap(line => line.split(" "))
        val counts = words.map(word => (word, 1)).reduceByKey{case (x, y) => x + y}
        counts.saveAsTextFile(outputFile)
    }

}

Answer 4

package com.application.spark

import org.apache.spark
import org.apache.spark.sql.SparkSession
import org.apache.spark.{SparkConf, SparkContext}

object WordCountDemo {
  def main(args: Array[String]): Unit = {
    //With using SparkContext
    val inputFile = "/Users/arupprasad/Desktop/MyFirstApplicationWithSpark1/src/main/resources/WordCountFile.txt"
    val outputFile = "/Users/arupprasad/Desktop/MyFirstApplicationWithSpark1/src/main/resources/WordCountOutput"
    val conf = new SparkConf().setAppName("wordCount").setMaster("local[*]")
    val sc = new SparkContext(conf)
    val input =  sc.textFile(inputFile)
    val words = input.flatMap(line => line.split(" "))
    val counts = words.map(word => (word, 1)).reduceByKey{case (x, y) => x + y}

    counts.saveAsTextFile(outputFile)

    //With using SparkSession
    val sparkSession = SparkSession.builder.master("local").appName("Scala Spark Example").getOrCreate()

    // import sparkSession.implicits._
    val sparkContext = sparkSession.sparkContext

    val inputFile = "/Users/arupprasad/Desktop/MyFirstApplicationWithSpark1/src/main/resources/WordCountFile.txt"
    val outputFile = "/Users/arupprasad/Desktop/MyFirstApplicationWithSpark1/src/main/resources/WordCountOutput"
    val input =  sparkContext.textFile(inputFile)
    val words = input.flatMap(line => line.split(" "))
    val counts = words.map(word => (word, 1)).reduceByKey{case (x, y) => x + y}

    counts.saveAsTextFile(outputFile)
  }
}