NOTE: Starting from version 0.3.0 of the library:

The library runtime is published to Maven Central and no longer published to Bintray.

The Gradle plugin is published to Gradle Plugin Portal

The Gradle plugin id has changed to org.jetbrains.kotlinx.benchmark

The library runtime artifact id has changed to kotlinx-benchmark-runtime

kotlinx.benchmark is a toolkit for running benchmarks for multiplatform code written in Kotlin and running on the following supported targets: JVM, JavaScript and Native.

Both Legacy and IR backends are supported for JS, however kotlin.js.compiler=both or js(BOTH) target declaration won't work. You should declare each targeted backend separately. See build script of the kotlin-multiplatform example project.

On JVM JMH is used under the hoods to run benchmarks. This library has a very similar way of defining benchmark methods. Thus, using this library you can run your JMH-based Kotlin/JVM benchmarks on other platforms with minimum modifications, if any at all.

Requirements

Gradle 7.0 or newer

Kotlin 1.7.20 or newer

Gradle plugin

Use plugin in build.gradle:

plugins {
    id 'org.jetbrains.kotlinx.benchmark' version '0.4.4'
}

For Kotlin/JS specify building nodejs flavour:

kotlin {
    js {
        nodejs()
        …
    }   
}

For Kotlin/JVM code, add allopen plugin to make JMH happy. Alternatively, make all benchmark classes and methods open.

For example, if you annotated each of your benchmark classes with @State(Scope.Benchmark):

@State(Scope.Benchmark)
class Benchmark {
    …
}

and added the following code to your build.gradle:

plugins {
    id 'org.jetbrains.kotlin.plugin.allopen'
}

allOpen {
    annotation("org.openjdk.jmh.annotations.State")
}

then you don't have to make benchmark classes and methods open.

Runtime Library

You need a runtime library with annotations and code that will run benchmarks.

Enable Maven Central for dependencies lookup:

repositories {
    mavenCentral()
}

Add the runtime to dependencies of the platform source set, e.g.:

kotlin {
    sourceSets {
        commonMain {
             dependencies {
                 implementation("org.jetbrains.kotlinx:kotlinx-benchmark-runtime:0.4.4")
             }
        }
    }
}

Configuration

In a build.gradle file create benchmark section, and inside it add a targets section. In this section register all compilations you want to run benchmarks for. register should either be called on the name of a target (e.g. "jvm") which will register its main compilation (meaning that register("jvm") and register("jvmMain") register the same compilation) Or on the name of a source set (e.g. "jvmTest", "jsBenchmark") which will register the apt compilation (e.g. register("jsFoo") uses the foo compilation defined for the js target) Example for multiplatform project:

benchmark {
    targets {
        register("jvm") 
        register("js")
        register("native")
        register("wasmJs") // Experimental
    }
}

This package can also be used for Java and Kotlin/JVM projects. Register a Java sourceSet as a target:

benchmark {
    targets {
        register("main") 
    }
}

To configure benchmarks and create multiple profiles, create a configurations section in the benchmark block, and place options inside. Toolkit creates main configuration by default, and you can create as many additional configurations, as you need.

benchmark {
    configurations {
        main { 
            // configure default configuration
        }
        smoke { 
            // create and configure "smoke" configuration, e.g. with several fast benchmarks to quickly check
            // if code changes result in something very wrong, or very right. 
        }       
    }
}

Available configuration options:

iterations – number of measuring iterations
warmups – number of warm up iterations
iterationTime – time to run each iteration (measuring and warmup)
iterationTimeUnit – time unit for iterationTime (default is seconds)
outputTimeUnit – time unit for results output
mode
- "thrpt" (default) – measures number of benchmark function invocations per time
- "avgt" – measures time per benchmark function invocation
include("…") – regular expression to include benchmarks with fully qualified names matching it, as a substring
exclude("…") – regular expression to exclude benchmarks with fully qualified names matching it, as a substring
param("name", "value1", "value2") – specify a parameter for a public mutable property name annotated with @Param
reportFormat – format of report, can be json(default), csv, scsv or text
There are also some advanced platform-specific settings that can be configured using advanced("…", …) function, where the first argument is the name of the configuration parameter, and the second is its value. Valid options:
- (Kotlin/Native) nativeFork
  - "perBenchmark" (default) – executes all iterations of a benchmark in the same process (one binary execution)
  - "perIteration" – executes each iteration of a benchmark in a separate process, measures in cold Kotlin/Native runtime environment
- (Kotlin/Native) nativeGCAfterIteration – when set to true, additionally collects garbage after each measuring iteration (default is false).
- (Kotlin/JVM) jvmForks – number of times harness should fork (default is 1)
  - a non-negative integer value – the amount to use for all benchmarks included in this configuration, zero means "no fork"
  - "definedByJmh" – let the underlying JMH determine, which uses the amount specified in @Fork annotation defined for the benchmark function or its enclosing class, or Defaults.MEASUREMENT_FORKS (5) if it is not specified by @Fork.
- (Kotlin/Js and Wasm) jsUseBridge – when false disables to generate special benchmark bridges to prevent inlining optimisations (only for BuiltIn benchmark executors).

Time units can be NANOSECONDS, MICROSECONDS, MILLISECONDS, SECONDS, MINUTES, or their short variants such as "ms" or "ns".

Example:

benchmark {
    // Create configurations
    configurations {
        main { // main configuration is created automatically, but you can change its defaults
            warmups = 20 // number of warmup iterations
            iterations = 10 // number of iterations
            iterationTime = 3 // time in seconds per iteration
        }
        smoke {
            warmups = 5 // number of warmup iterations
            iterations = 3 // number of iterations
            iterationTime = 500 // time in seconds per iteration
            iterationTimeUnit = "ms" // time unit for iterationTime, default is seconds
        }   
    }
    
    // Setup targets
    targets {
        // This one matches compilation base name, e.g. 'jvm', 'jvmTest', etc
        register("jvm") {
            jmhVersion = "1.21" // available only for JVM compilations & Java source sets
        }
        register("js") {
            // Note, that benchmarks.js uses a different approach of minTime & maxTime and run benchmarks
            // until results are stable. We estimate minTime as iterationTime and maxTime as iterationTime*iterations
            //
            // You can configure benchmark executor - benchmarkJs or buildIn (works only for JsIr backend) with the next line:
            // jsBenchmarksExecutor = JsBenchmarksExecutor.BuiltIn
        }
        register("native")
        register("wasmJs") // Experimental
    }
}

Separate source sets for benchmarks

Often you want to have benchmarks in the same project, but separated from main code, much like tests. Here is how: For a Kotlin/JVM project:

Define source set:

sourceSets {
    benchmarks
}

Propagate dependencies and output from main sourceSet.

dependencies {
    benchmarksCompile sourceSets.main.output + sourceSets.main.runtimeClasspath 
}

You can also add output and compileClasspath from sourceSets.test in the same way if you want to reuse some of the test infrastructure.

benchmark {
    targets {
        register("benchmarks")    
    }
}

For a Kotlin Multiplatform project:

Define a new compilation in whichever target you'd like (e.g. jvm, js, etc):

kotlin {
    jvm {
        compilations.create('benchmark') { associateWith(compilations.main) }
    }
}

benchmark {
    targets {
        register("jvmBenchmark")    
    }
}

Examples