Elasticsearch Java API from web application-error: java.lang.NoClassDefFoundError: Could not initialize class org.elasticsearch.threadpool.ThreadPool

Question

I couldn't use elasticsearch Java API through JSP. In the following, I have tried to explain what I have done. :|

I have installed elasticseach 2.3.3 on my system by following the elastic instruction and run it from command prompt. everything is working perfectly. It may be useful to say, I have changed below parameters from elasticsearch.yml.

cluster.name: cluster_233
node.name: node_233
bootstrap.mlockall: true
network.host: 127.0.0.1

Then with Netbeans, I have created a Maven project -> Web application project and set the below dependency in pom.xml :

<dependency>
   <groupId>org.elasticsearch</groupId>
   <artifactId>elasticsearch</artifactId>
   <version>2.3.3</version>
   <type>jar</type>
</dependency>

Also I have added the Guava version 18 dependency into project and then download all the project dependencies by right clicking on Dependencies and select Download Declared Dependencies . Then created a java class and write below code:

package com.mycompany.esmaven;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.elasticsearch.client.Client;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.node.Node;
import org.elasticsearch.node.NodeBuilder;

public class aClass {

    public String test() throws Exception {

        String str = tryToIndex();

        String dfd = "";
        return str;
    }

    public String tryToIndex() throws Exception {

        Node node = NodeBuilder.nodeBuilder().settings(
                Settings.builder()
                        .put("path.home", "d:/elasticsearch-2.3.3")
                        .put("cluster.home", "cluster_233")

        ).node();

        Client client = node.client();
        client.prepareIndex("kodcucom", "article", "1")
                .setSource(putJsonDocument("ElasticSearch: Java API",
                        "ElasticSearch provides the Java API, all operations "
                        + "can be executed asynchronously using a client object.",
                        new Date(),
                        new String[]{"elasticsearch"},
                        "Hüseyin Akdoğan")).execute().actionGet();
        node.close();

        return "Done";
    }

    public static Map<String, Object> putJsonDocument(String title,
            String content, Date postDate, String[] tags, String author) {

        Map<String, Object> jsonDocument = new HashMap<String, Object>();
        jsonDocument.put("title", title);
        jsonDocument.put("conten", content);
        jsonDocument.put("postDate", postDate);
        jsonDocument.put("tags", tags);
        jsonDocument.put("author", author);
        return jsonDocument;
    }

}

And through a jsp page tried to call the test() function (I'm going to integrate elasticsearch with a web application). Always after building the project at the first load the below error will appear:

java.lang.NoSuchMethodError: com.google.common.util.concurrent.MoreExecutors.directExecutor()Ljava/util/concurrent/Executor;

and after refreshing the page the context of error will change to:

java.lang.NoClassDefFoundError: Could not initialize class org.elasticsearch.threadpool.ThreadPool

This is the POM:

<?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>com.ISTEX</groupId>
    <artifactId>mvnESwebapp</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>mvnESwebapp</name>

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.1</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>2.3.3</version>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

Also, I would like to mention, with this POM I can index my JSON from the main function. But the problem is I did not know how to run the application through JSP pages.

I really appreciate you for sharing your knowledge.

Regards, Amin

Answer 1

FWIW, I ran into the same issue as described above -- that is, the error message I saw was the threadpool initialization error the author describes. The solution described in the link below solved the problem for me: https://discuss.elastic.co/t/could-not-initialize-class-org-elasticsearch-threadpool-threadpool/47575

UPDATED per comment suggestion: In my case, the fix was to add a guava dependency entry in my POM file. I used the dependency given in the webpage at the link above:

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>19.0</version>
</dependency>

That, at least in my case, solved the problem.

Answer 2

With Java applications, errors like

• java.lang.NoSuchMethodError
• java.lang.NoClassDefFoundError

generally indicate that you are missing a dependency or you have conflicting dependency. For example, Guava 18.0 and Guava 19.0 are completely different as far as Java is concerned, but they share a lot of code. As the jars are loaded, one will naturally be loaded first, so any attempted usage of the second will cause misleading errors like those above.

Also I have added the Guava version 18 dependency into project and then download all the project dependencies by right clicking on Dependencies and select Download Declared Dependencies

Elasticsearch 2.3.3 already depends on Guava 18.0. As such, it's a transitive dependency of the Elasticsearch project.

<dependency>
   <groupId>org.elasticsearch</groupId>
   <artifactId>elasticsearch</artifactId>
   <version>2.3.3</version>
   <type>jar</type>
</dependency>

Your Maven dependency is probably creating a collision with one of your other dependencies. Take a look at your Netbeans dependencies, or more appropriately ask Maven to do it directly:

mvn dependency:tree -Dverbose

This will print out the dependency tree for you to find conflicts. Look for jars that are duplicated with different versions and stop the mismatch from happening.

As a side note, at the time of this answer, Guava 19 is the latest version. So even though ES 2.3.3 wants Guava 18, some other dependency of yours could easily and reasonably want a different version of Guava.