How to use JMH with gradle?

Question

I want to use JMH, an OpenJDK microbenchmark tool, with gradle. However, Im getting the NPE on compilation. On the other hand, JMH works when using from maven.<

Answer 1

My bad, I was trying to benchmark a method that has an argument - of course JMH will not know what to pass :) Once when I created a void method with no arguments, everything worked.

My build.gradle:

defaultTasks 'build'

apply plugin: 'java'
apply plugin: 'shadow'

buildscript {
    repositories {
        mavenCentral()
        maven {
            name 'Shadow'
            url 'http://dl.bintray.com/content/johnrengelman/gradle-plugins'
        }
    }
    dependencies {
        classpath 'org.gradle.plugins:shadow:0.7.4'
    }
}

jar {
    manifest {
        attributes 'Main-Class': 'org.openjdk.jmh.Main'
    }
}

repositories {
    mavenCentral()
}


build.doLast {
    tasks.shadow.execute()
}

shadow {
    outputFile = new File('build/libs/microbenchmarks.jar')
}

ext {
    lib = [
        ... other dependencies...
        jmh:            'org.openjdk.jmh:jmh-core:0.2'
    ]
}

dependencies {
    compile lib... other dependencies...
    compile lib.jmh
}

sourceCompatibility = 1.7

Build tests and jar:

gw clean build

and then run them with:

java -jar build/libs/microbenchmarks.jar ".*" -wi 2 -i 10 -f 2 -t 16

UPDATE

From recent versions of JMH, you would also need to add dependency to:

org.openjdk.jmh:jmh-generator-annprocess:0.5.4

and you can use shadow 0.8.