ThreadSleepStats.kt

import kotlin.math.abs

typealias Duration = Long
typealias Sample = Long

object ThreadSleepStats {

    @JvmStatic
    fun main(args: Array<String>) {
        val durations = listOf(1L, 10L, 100L, 1000L)
        val durationSamples = mutableMapOf<Duration, MutableList<Sample>>()
        val numSamples = 100

        for(sampleIndex in 0 until numSamples) {
            for(duration in durations) {
                val startTime = System.nanoTime()
                Thread.sleep(duration)
                val endTime = System.nanoTime()
                
                val timeDiff = endTime - startTime
                val samples = durationSamples.getOrDefault(duration, mutableListOf())
                samples += timeDiff
                durationSamples[duration] = samples
            }
        }

        for((duration, samples) in durationSamples) {
            val summedSamples = samples.sum()
            val mean = nanoToMillis(summedSamples) / numSamples
            val mad = (samples.fold(0.0) { acc, sample -> acc + abs((nanoToMillis(sample) - mean)) }) / numSamples

            val meanFormatted = String.format("%.6f", mean)
            val madFormatted = String.format("%.6f", mad)
            
            println("Sleep($duration ms) stats:")
            println("Mean: ${meanFormatted}ms")
            println("Mean Absolute Deviation (MAD): ${madFormatted}ms\n")
        }
    }

    /*
    Can't use TimeUnit as values are truncated going from finer to coarser granularity
     */
    private fun nanoToMillis(nanoTime: Long): Double
            = nanoTime / 1E6
}