Track execution time per task in gradle script?

What is the most elegant way to track the execution times on how long a task took in a gradle build script? In an optimal case, log the time directly same or next line to the task name:

:buildSrc:testClasses (0.518 secs)
:fooBar (28.652 secs)

Just to elaborate on Peter Niederwieser's answer: We wanted to do the same thing, as well as a report timings at the end of the build, so slow steps are obvious (and appropriate parties feel a small but healthy bit of shame when they slow down the build!).

BUILD SUCCESSFUL

Total time: 1 mins 37.973 secs
Task timings:
    579ms  :myproject-foo:clean
  15184ms  :myproject-bar:clean
   2839ms  :myproject-bar:compileJava
  10157ms  :myproject-bar:jar
    456ms  :myproject-foo:compileJava
    391ms  :myproject-foo:libs
    101ms  :myproject-foo:jar
    316ms  :myproject-bar:compileTestJava
    364ms  :myproject-foo:compileTestJava
  53353ms  :myproject-foo:test
   2146ms  :myproject-bar:test
   8348ms  :www/node:npmInstall
    687ms  :www/node:npmTest

Something like the code below can be dropped into your top level build.gradle to report timings during execution, or after completion.

// Log timings per task.
class TimingsListener implements TaskExecutionListener, BuildListener {
    private Clock clock
    private timings = []

    @Override
    void beforeExecute(Task task) {
        clock = new org.gradle.util.Clock()
    }

    @Override
    void afterExecute(Task task, TaskState taskState) {
        def ms = clock.timeInMs
        timings.add([ms, task.path])
        task.project.logger.warn "${task.path} took ${ms}ms"
    }

    @Override
    void buildFinished(BuildResult result) {
        println "Task timings:"
        for (timing in timings) {
            if (timing[0] >= 50) {
                printf "%7sms  %s\n", timing
            }
        }
    }

    @Override
    void buildStarted(Gradle gradle) {}

    @Override
    void projectsEvaluated(Gradle gradle) {}

    @Override
    void projectsLoaded(Gradle gradle) {}

    @Override
    void settingsEvaluated(Settings settings) {}
}

gradle.addListener new TimingsListener()

This is a variation of jlevy's answer which has been modified to remove the usage of the publicly accessible gradle Clock class, which has been deprecated.

BUILD SUCCESSFUL

Total time: 1 mins 37.973 secs
Task timings:
    579ms  :myproject-foo:clean
  15184ms  :myproject-bar:clean
   2839ms  :myproject-bar:compileJava
  10157ms  :myproject-bar:jar
    456ms  :myproject-foo:compileJava
    391ms  :myproject-foo:libs
    101ms  :myproject-foo:jar
    316ms  :myproject-bar:compileTestJava
    364ms  :myproject-foo:compileTestJava
  53353ms  :myproject-foo:test
   2146ms  :myproject-bar:test
   8348ms  :www/node:npmInstall
    687ms  :www/node:npmTest

Something like the code below can be dropped into your top level build.gradle to report timings during execution, or after completion.

import java.util.concurrent.TimeUnit
// Log timings per task.
class TimingsListener implements TaskExecutionListener, BuildListener {
    private long startTime
    private timings = []

    @Override
    void beforeExecute(Task task) {
        startTime = System.nanoTime()
    }

    @Override
    void afterExecute(Task task, TaskState taskState) {
        def ms = TimeUnit.MILLISECONDS.convert(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
        timings.add([ms, task.path])
        task.project.logger.warn "${task.path} took ${ms}ms"
    }

    @Override
    void buildFinished(BuildResult result) {
        println "Task timings:"
        for (timing in timings) {
            if (timing[0] >= 50) {
                printf "%7sms  %s\n", timing
            }
        }
    }

    @Override
    void projectsEvaluated(Gradle gradle) {}

    @Override
    void projectsLoaded(Gradle gradle) {}

    @Override
    void settingsEvaluated(Settings settings) {}
}

gradle.addListener new TimingsListener()

The cleanest solution is to implement a TaskExecutionListener (I'm sure you can handle that part) and register it with gradle.taskGraph.addTaskExecutionListener.

I know this is an old question, but I've found a cool plugin that does task timing. It's like @jlevy's answer, but with some more options available: https://github.com/passy/build-time-tracker-plugin

This plugin by Pascal Hartig continuously logs your build times and provides CSV and bar chart summaries. The developer recommends it for monitoring your build times over time, versus --profile which gives you a snapshot for the current build.

This is how I'm currently using it:

buildscript {
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath "net.rdrei.android.buildtimetracker:gradle-plugin:0.7.+"
    }
}

apply plugin: "build-time-tracker"

buildtimetracker {
    reporters {
        summary {
            ordered false
            threshold 50
            barstyle 'unicode'
        }
    }
}