java.lang.NoClassDefFoundError: com.trueaccord.scalapb.GeneratedEnum with Gatling Maven Plugin

Question

Using the latest OpenJDK 11.0.7 with the Gatling Maven Plugin is resulting in this compilation crash. I tried deleting the local Maven repository folders for Gatling, scala-lang, and scala-sbt and re-running a clean install. Below I've pasted my pom.xml. Can someone help to resolve this?

java.lang.ClassNotFoundException: com.trueaccord.scalapb.GeneratedEnum
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:766)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:1078)
    ... 31 common frames omitted
Wrapped by: java.lang.NoClassDefFoundError: com.trueaccord.scalapb.GeneratedEnum
    at java.base/java.lang.ClassLoader.defineClassImpl(Native Method)
    at java.base/java.lang.ClassLoader.defineClassInternal(ClassLoader.java:476)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:437)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:1110)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:898)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:806)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:764)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:1078)
    at sbt.internal.inc.FileAnalysisStore$BinaryFileStore.<init>(FileAnalysisStore.scala:50)
    at sbt.internal.inc.FileAnalysisStore$.binary(FileAnalysisStore.scala:36)
    at io.gatling.compiler.ZincCompiler$.doCompile(ZincCompiler.scala:174)
    at io.gatling.compiler.ZincCompiler$.delayedEndpoint$io$gatling$compiler$ZincCompiler$1(ZincCompiler.scala:216)
    at io.gatling.compiler.ZincCompiler$delayedInit$body.apply(ZincCompiler.scala:39)
    at scala.Function0.apply$mcV$sp(Function0.scala:39)
    at scala.Function0.apply$mcV$sp$(Function0.scala:39)
    at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
    at scala.App.$anonfun$main$1$adapted(App.scala:80)
    at scala.App$$Lambda$5/0000000000000000.apply(Unknown Source)
    at scala.collection.immutable.List.foreach(List.scala:392)
    at scala.App.main(App.scala:80)
    at scala.App.main$(App.scala:78)
    at io.gatling.compiler.ZincCompiler$.main(ZincCompiler.scala:39)
    at io.gatling.compiler.ZincCompiler.main(ZincCompiler.scala)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at io.gatling.mojo.MainWithArgsInFile.runMain(MainWithArgsInFile.java:50)
    at io.gatling.mojo.MainWithArgsInFile.main(MainWithArgsInFile.java:33)

My redacted pom.xml:

<?xml version="1.0"?>
<project 
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    <modelVersion>4.0.0</modelVersion>

    <groupId>***</groupId>
    <artifactId>****</artifactId>
    <version>1.0</version>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <gatling.version>3.3.1</gatling.version>
        <gatling-plugin.version>3.0.5</gatling-plugin.version>
        <maven-jar-plugin.version>3.2.0</maven-jar-plugin.version>
        <!-- <scala-maven-plugin.version>4.3.1</scala-maven-plugin.version> -->
    </properties>

    <dependencies>
        <dependency>
            <groupId>io.gatling.highcharts</groupId>
            <artifactId>gatling-charts-highcharts</artifactId>
            <version>${gatling.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <testSourceDirectory>simulations</testSourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-jar-plugin</artifactId>
                <version>${maven-jar-plugin.version}</version>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.6.0</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>exec</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <executable>bash</executable>
                    <arguments>
                        <argument>run.sh</argument>
                        <argument>${env.NS}</argument> <!-- will be empty if running with services -->
                    </arguments>
                </configuration>
            </plugin>
            <plugin>
                <groupId>io.gatling</groupId>
                <artifactId>gatling-maven-plugin</artifactId>
                <version>${gatling-plugin.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>test</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <!-- the name of the single Simulation class to run -->
                    <simulationClass>${env.SIMULATION}</simulationClass>
                    <runMultipleSimulations>false</runMultipleSimulations>                   <!-- if the plugin should run multiple simulations sequentially -->
                    <includes>                                                               <!-- include filters, see dedicated section below -->
                        <include></include>
                    </includes>
                    <excludes>                                                               <!-- exclude filters, see dedicated section below -->
                        <exclude></exclude>
                    </excludes>
                    <reportsOnly></reportsOnly>                                              <!-- to only trigger generating HTML reports from the log file contained in folder parameter -->
                    <runDescription>****</runDescription>             <!-- short text that will be displayed in the HTML reports -->
                    <failOnError>true</failOnError>                                          <!-- report failure in case of assertion failure, typically to fail CI pipeline -->
                    <continueOnAssertionFailure>false</continueOnAssertionFailure>           <!-- keep on executing multiple simulations even if one fails -->
                    <useOldJenkinsJUnitSupport>true</useOldJenkinsJUnitSupport>             <!-- report results to Jenkins JUnit support (workaround until we manage to get Gatling support into Jenkins) -->
                    <!-- pass extra parameters to the Gatling JVM -->
                    <jvmArgs>
                        <jvmArg>-DIAM=${env.IAM}</jvmArg>
                        <jvmArg>-DStarterkitsDir=${env.STARTERKITS_DIR}</jvmArg>
                        <jvmArg>-DServicesDir=${env.SERVICES_DIR}</jvmArg>
                        <jvmArg>-DGROUP=${env.RESOURCE_GROUP}</jvmArg>
                        <jvmArg>-DGORG=${env.ORG_GUID}</jvmArg>
                        <jvmArg>-DSPACE=${env.SPACE_GUID}</jvmArg>
                        <jvmArg>-DURL=${env.URL}</jvmArg>
                        <jvmArg>-DUsers=${env.USERS}</jvmArg>
                        <jvmArg>-DDuration=${env.DURATION}</jvmArg>
                    </jvmArgs>
                    <overrideJvmArgs>false</overrideJvmArgs>                                 <!-- if above option should override the defaults instead of replacing them -->
                    <propagateSystemProperties>true</propagateSystemProperties>              <!-- if System properties from the maven JVM should be propagated to the Gatling forked one -->
                    <!-- pass extra parameters to the Compiler JVM -->
                    <compilerJvmArgs>
                    </compilerJvmArgs>
                    <!-- if above option should override the defaults instead of replacing them -->
                    <overrideCompilerJvmArgs>false</overrideCompilerJvmArgs>    
                    <!-- extra options to be passed to scalac -->             
                    <!-- <extraScalacOptions>                                                     
                        <extraScalacOption></extraScalacOption>
                    </extraScalacOptions> -->
                    <disableCompiler>false</disableCompiler>                                 <!-- if compiler should be disabled, typically because another plugin has already compiled sources -->
                    <simulationsFolder>${project.basedir}/simulations</simulationsFolder> <!-- where the simulations to be compiled are located -->
                    <resourcesFolder>${project.basedir}</resourcesFolder> <!-- where the test resources are located -->
                    <resultsFolder>${project.basedir}/target/gatling</resultsFolder>         <!-- where the simulation log and the HTML reports will be generated -->
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

There's nothing wrong with gatling-maven-plugin.

As I said in the issue you opened on our bug tracker, you most likely have some corrupted jars in your local maven repository.

Maven sometimes messes up when downloading jars and still installs the corrupted files in the local repository. The ClassLoader can't open the jars (jars are just zip files) and silently ignores them, causing NoClassDefFoundErrors at runtime.

Answer 2

It looks like the gatling-maven-plugin compilation is not working or something else is going on with it. I switched to using scala-maven-plugin and that compiles my simulation classes successfully.

            <plugin>
                <groupId>net.alchim31.maven</groupId>
                <artifactId>scala-maven-plugin</artifactId>
                <version>${scala-maven-plugin.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                        <configuration>
                            <jvmArgs>
                                <jvmArg>-Xss100M</jvmArg>
                            </jvmArgs>
                            <args>
                                <arg>-target:jvm-1.8</arg>
                                <arg>-deprecation</arg>
                                <arg>-feature</arg>
                                <arg>-unchecked</arg>
                                <arg>-language:implicitConversions</arg>
                                <arg>-language:postfixOps</arg>
                            </args>
                        </configuration>
                    </execution>
                </executions>
            </plugin>