preciseSleep.kt

    @Test
    fun sleepParkNanos() {
        val nsec = 960 * 1000_000_000L / 48000

        val looping = AtomicBoolean(true)
        val histo = IntArray(10)
        val t = Thread() {
            val startTime = System.nanoTime()
            var i = 0
            while (looping.get()) {
                val expected = i * nsec
                val actual = System.nanoTime() - startTime
                val dnsec = actual - expected
                val dmsec = TimeUnit.NANOSECONDS.toMillis(dnsec).toInt()
                histo[dmsec]++
//                println(message)
                LockSupport.parkNanos(nsec - dnsec)
                i++
            }
        }
        t.priority = MAX_PRIORITY
        t.start()
        Thread.sleep(20000)
        looping.set(false)
        println(histo.contentToString())
        println("done")

    }

on ubuntu 22 + openjdk 17 this produces:

[1000, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

meaning - it schedules execution after parkNanos at exactly the requested time at millisecond resolution

on macos 12 + temurin 17 this produces

[191, 224, 149, 320, 115, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

meaning it scheduled 191 times at 0 msec from expected time, 224 times 1 msec later, etc