All posts tagged scala

IntelliJ IDEA supports Scala and Apache Spark perfectly. You're able to browse a complete Spark project built with IntelliJ IDEA on GitHub: https://github.com/vinta/albedo

Useful Plugins:

• https://plugins.jetbrains.com/plugin/1347-scala
• https://plugins.jetbrains.com/plugin/9333-makefile-support

Initiate a Maven Project

$ mvn archetype:generate
Choose a number: xxx
xxx: remote -> net.alchim31.maven:scala-archetype-simple

ref:
https://docs.scala-lang.org/tutorials/scala-with-maven.html

Example Configurations

The remaining section of this article assumes that you use this pom.xml which should be able to work out of the box.

<!-- in pom.xml -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>ws.vinta</groupId>
  <artifactId>albedo</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>${project.artifactId}</name>
  <description>A recommender system for discovering GitHub repos</description>
  <url>https://github.com/vinta/albedo</url>
  <inceptionYear>2017</inceptionYear>
  <properties>
    <java.version>1.8</java.version>
    <scala.version>2.11.8</scala.version>
    <scala.compactVersion>2.11</scala.compactVersion>
    <spark.version>2.2.0</spark.version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <repositories>
    <repository>
      <id>spark-packages</id>
      <name>Spark Packages Repository</name>
      <url>https://dl.bintray.com/spark-packages/maven/</url>
    </repository>
  </repositories>
  <dependencies>
    <!-- https://mvnrepository.com/artifact/org.scala-lang/scala-library -->
    <dependency>
      <groupId>org.scala-lang</groupId>
      <artifactId>scala-library</artifactId>
      <version>${scala.version}</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-core_2.11 -->
    <dependency>
      <groupId>org.apache.spark</groupId>
      <artifactId>spark-core_${scala.compactVersion}</artifactId>
      <version>${spark.version}</version>
      <scope>compile</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-sql_2.11 -->
    <dependency>
      <groupId>org.apache.spark</groupId>
      <artifactId>spark-sql_${scala.compactVersion}</artifactId>
      <version>${spark.version}</version>
      <scope>compile</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.spark/spark-mllib_2.11 -->
    <dependency>
      <groupId>org.apache.spark</groupId>
      <artifactId>spark-mllib_${scala.compactVersion}</artifactId>
      <version>${spark.version}</version>
      <scope>compile</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.42</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
    <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.2</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.elasticsearch.client/elasticsearch-rest-high-level-client -->
    <dependency>
      <groupId>org.elasticsearch.client</groupId>
      <artifactId>elasticsearch-rest-high-level-client</artifactId>
      <version>5.6.2</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/com.hankcs/hanlp -->
    <dependency>
      <groupId>com.hankcs</groupId>
      <artifactId>hanlp</artifactId>
      <version>portable-1.3.4</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/com.github.rholder/snowball-stemmer -->
    <dependency>
      <groupId>com.github.rholder</groupId>
      <artifactId>snowball-stemmer</artifactId>
      <version>1.3.0.581.1</version>
    </dependency>
  </dependencies>
  <build>
    <sourceDirectory>src/main/scala</sourceDirectory>
    <testSourceDirectory>src/test/scala</testSourceDirectory>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.6.1</version>
        <configuration>
          <source>${java.version}</source>
          <target>${java.version}</target>
          <encoding>UTF-8</encoding>
        </configuration>
      </plugin>
      <plugin>
        <groupId>net.alchim31.maven</groupId>
        <artifactId>scala-maven-plugin</artifactId>
        <version>3.2.1</version>
        <executions>
          <execution>
            <goals>
              <goal>compile</goal>
              <goal>testCompile</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-install-plugin</artifactId>
        <version>2.5.2</version>
        <configuration>
          <skip>true</skip>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.1.0</version>
        <executions>
          <execution>
           <phase>install</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <filters>
                <filter>
                  <artifact>*:*</artifact>
                  <excludes>
                    <exclude>META-INF/*.DSA</exclude>
                    <exclude>META-INF/*.RSA</exclude>
                    <exclude>META-INF/*.SF</exclude>
                  </excludes>
                </filter>
              </filters>
              <artifactSet>
                <excludes>
                  <exclude>com.apple:AppleJavaExtensions:*</exclude>
                  <exclude>javax.servlet:*</exclude>
                  <exclude>org.apache.hadoop:*</exclude>
                  <exclude>org.apache.maven.plugins:*</exclude>
                  <exclude>org.apache.parquet:*</exclude>
                  <exclude>org.apache.spark:*</exclude>
                  <exclude>org.scala-lang:*</exclude>
                </excludes>
              </artifactSet>
              <finalName>${project.artifactId}-${project.version}-uber</finalName>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

ref:
https://davidb.github.io/scala-maven-plugin/example_compile.html

Generate a Thin JAR

Thin JAR only contains classes that you created, which means you should include your dependencies externally.

$ mvn clean package -DskipTests

You're able to specify different classes in the same JAR.

$ spark-submit \
--master spark://localhost:7077 \
--packages "mysql:mysql-connector-java:5.1.41" \
--class ws.vinta.albedo.LogisticRegressionRanker \
target/albedo-1.0.0-SNAPSHOT.jar

ref:
https://stackoverflow.com/questions/1082580/how-to-build-jars-from-intellij-properly
https://spark.apache.org/docs/latest/submitting-applications.html

Generate a Fat JAR, Shaded JAR or Uber JAR

CAUTION: DO NOT ENABLE <minimizeJar>true</minimizeJar> in the maven-shade-plugin, it will ruin your day!

<!-- in pom.xml -->
<project>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-install-plugin</artifactId>
        <version>2.5.2</version>
        <configuration>
          <skip>true</skip>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.1.0</version>
        <executions>
          <execution>
            <phase>install</phase>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <artifactSet>
                <excludes>
                  <exclude>com.apple:AppleJavaExtensions:*</exclude>
                  <exclude>javax.servlet:*</exclude>
                  <exclude>org.apache.hadoop:*</exclude>
                  <exclude>org.apache.maven.plugins:*</exclude>
                  <exclude>org.apache.parquet:*</exclude>
                  <exclude>org.apache.spark:*</exclude>
                  <exclude>org.scala-lang:*</exclude>
                </excludes>
              </artifactSet>
              <finalName>${project.artifactId}-${project.version}-uber</finalName>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

# the output jar will be located in "target/albedo-1.0.0-SNAPSHOT-uber.jar"
$ mvn clean install -DskipTests

$ spark-submit \
--master spark://localhost:7077 \
--class ws.vinta.albedo.LogisticRegressionRanker \
target/albedo-1.0.0-SNAPSHOT-uber.jar

ref:
http://maven.apache.org/plugins/maven-shade-plugin/examples/includes-excludes.html
https://databricks.gitbooks.io/databricks-spark-knowledge-base/content/troubleshooting/missing_dependencies_in_jar_files.html

Run a Spark Application in Local Mode

Follow "Run > Edit Configurations":

• VM options: -Xms12g -Xmx12g -Dspark.master="local[*]"
• Before launch:
  • Build

Or

// in YourSparkApp.scala
package ws.vinta.albedo

import org.apache.spark.SparkConf
import org.apache.spark.sql.SparkSession

object YourSparkApp {
  def main(args: Array[String]): Unit = {
    val conf = new SparkConf()
      .setMaster("local[*]")
      .set("spark.driver.memory", "12g")

    val spark = SparkSession
      .builder()
      .appName("YourSparkApp")
      .config(conf)
      .getOrCreate()

    spark.stop()
  }
}

ref:
https://github.com/jaceklaskowski/mastering-apache-spark-book/blob/master/spark-sparkcontext-creating-instance-internals.adoc
https://stackoverflow.com/questions/43054268/how-to-set-spark-memorystore-size-when-running-in-intellij-scala-console

Run a Spark Application in Standalone Mode

First, start your Spark Standalone cluster:

$ cd ${SPARK_HOME}
$ ./sbin/start-master.sh -h 0.0.0.0
$ ./sbin/start-slave.sh spark://localhost:7077

# print logs from Spark master and workers, useful for debuging
$ tail -f ${SPARK_HOME}/logs/*

Follow "Run > Edit Configurations":

• VM options: -Dspark.master=spark://localhost:7077 -Dspark.driver.memory=2g -Dspark.executor.memory=12g -Dspark.executor.cores=3
  • Local cluster mode: -Dspark.master="local-cluster[x, y, z]" with x workers, y cores per worker, and z MB memory per worker
  • Local cluster mode doesn't need a real Spark Standalone cluster
• Before launch:
  • Build
  • Run Maven Goal 'albedo: clean install'

Or

// in YourSparkApp.scala
package ws.vinta.albedo

import org.apache.spark.SparkConf
import org.apache.spark.sql.SparkSession

object YourSparkApp {
  def main(args: Array[String]): Unit = {
    val conf = new SparkConf()
      .setMaster("spark://localhost:7077")
      .set("spark.driver.memory", "2g")
      .set("spark.executor.memory", "12g")
      .set("spark.executor.cores", "3")
      .setJars(List("target/albedo-1.0.0-SNAPSHOT-uber.jar"))
      // or
      .setMaster("local-cluster[1, 3, 12288]")
      .setJars(List("target/albedo-1.0.0-SNAPSHOT-uber.jar"))

    val spark = SparkSession
      .builder()
      .appName("YourSparkApp")
      .config(conf)
      .getOrCreate()

    spark.stop()
  }
}

In the end, there are some glossaries which need to be clarified:

• compile: compile a single .java or .scala into *.class
• make: compile changed files only
• build: compile every files in the project

ref:
http://www.jianshu.com/p/b4e4658c459c

Specify a Custom Logging Configuration

$ cd PROJECT_ROOT
$ cp $SPARK_HOME/conf/log4j.properties.template log4j.properties

Follow "Run > Edit Configurations":

• VM options: -Dlog4j.configuration=file:./log4j.properties

ref:
https://spark.apache.org/docs/latest/sql-programming-guide.html#getting-started
https://stackoverflow.com/questions/43054268/how-to-set-spark-memorystore-size-when-running-in-intellij-scala-console
https://community.cloudera.com/t5/Advanced-Analytics-Apache-Spark/Config-log4j-in-Spark/td-p/34968