2

I am working with YarnClient for the 1st time. My goal is to get and display the applications running on Yarn using Java. My project setup is as follows:

public static void main(String[] args) throws IOException, YarnException {
    // Create yarnClient
    YarnConfiguration conf = new YarnConfiguration();
    YarnClient yarnClient = YarnClient.createYarnClient();
    yarnClient.init(conf);

    try {
        List applications = yarnClient.getApplications();
        System.err.println("yarn client : " + applications.size());
    } catch (YarnException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

I get the following exception when i run the program:

java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:293)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoClassDefFoundError: org/apache/hadoop/HadoopIllegalArgumentException
at projects.HelloWorld.main(HelloWorld.java:16)
... 6 more
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.HadoopIllegalArgumentException
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

The POM file is as follows:

    <?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>BigContent</groupId>
    <artifactId>ManagementServer</artifactId>
    <version>1.0-SNAPSHOT</version>


    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <hadoop.version>2.4.0</hadoop.version>
        <spark.version>1.2.1</spark.version>
    </properties>

    <build>
        <plugins>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.3</version>
                <executions>
                    <execution>
                        <!-- First step is to disable the default-war build step. -->
                        <id>default-war</id>
                        <phase>none</phase>
                    </execution>
                    <execution>
                        <!-- Second step is to create an exploded war. Done in prepare-package -->
                        <id>war-exploded</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>exploded</goal>
                        </goals>
                    </execution>
                    <execution>
                        <!-- Last step is to make sure that the war is built in the package phase -->
                        <id>custom-war</id>
                        <phase>package</phase>
                        <goals>
                            <goal>war</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <webXml>src/main/webapp/WEB-INF/web.xml</webXml>
                    <webResources>
                        <resource>
                            <!-- this is relative to the pom.xml directory -->
                            <directory>resource2</directory>
                        </resource>
                    </webResources>
                </configuration>
            </plugin>
        </plugins>
    </build>


    <dependencies>


        <dependency>
            <groupId>org.apache.spark</groupId>
            <artifactId>spark-streaming_2.10</artifactId>
            <version>${spark.version}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-core</artifactId>
            <version>1.9.1</version>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>${hadoop.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-yarn-common</artifactId>
            <version>${hadoop.version}</version>
        </dependency>


        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>${hadoop.version}</version>
            <scope>provided</scope>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.google.guava</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-core</artifactId>
            <version>${hadoop.version}</version>
        </dependency>

        <dependency>
            <groupId>json-mapreduce</groupId>
            <artifactId>json-mapreduce</artifactId>
            <version>1.0-SNAPSHOT</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>commons-io</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>commons-lang</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.apache.hadoop</groupId>
                    <artifactId>hadoop-common</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-core</artifactId>
            <version>0.20.2</version>
        </dependency>


        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>16.0</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.7</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.5.0</version>
        </dependency>



    </dependencies>


</project>

Can you please help me in fixing the issue, or if you can suggest a better way?

2 Answers 2

2

I changed the pom file's dependencies as follows and the
java.lang.ClassNotFoundException: org.apache.hadoop.HadoopIllegalArgumentException is fixed:

 <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-yarn-client</artifactId>
        <version>2.2.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>2.2.0</version>
    </dependency>

now i get a Null Pointer Exception at List applications = yarnClient.getApplications(); trying to resolve that now.

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Comments

0

After running into this same issue and looking around a bit, I found that after the creation of the YarnClient object, and after init'ing it, you also need to call start() on the object. This resolved the NullPointer on my end

YarnConfiguration yarnConfig = new YarnConfiguration();
YarnClient client = YarnClient.createYarnClient();
client.init(yarnConfig);
client.start();

client.getAllQueues(); //no longer throws NullPointer

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