suspendFunctionWithLock.kt

val lock = Any()
var latestValue: Int = 0

suspend fun runSuspendFunctionBadly(input: Int) {

    println("running suspend function with input $input")
    synchronized(lock) {
        delay(1000)
        latestValue = input
    }
    println("finished suspend function $input at ${System.currentTimeMillis()}")
}

suspendFunctionWithMutex.kt

companion object {
    val mutex = Mutex()
}

var latestValue: Int = 0

suspend fun runSuspendFunctionWithMutex(input: Int) {

    println("running suspend function with input $input")
    mutex.withLock {
        doubleOnServer(input)
        println("finished suspend function $input at ${System.currentTimeMillis()}")
        latestValue = input
    }
}

syncLocked.kt

val lock = Any()
var latestValue: Int = 0

fun runFunction(input: Int) {
    println("running function with input $input")
    synchronized(lock) {
        Thread.sleep(1000)
        latestValue = input
    }
    println("finished function $input at ${System.currentTimeMillis()}")
}

syncLockedAcrossInstances.kt

companion object {
    val staticLock = Any()
}

var latestValue: Int = 0
fun runFunctionAcrossInstances(input: Int) {
    println("running function with input $input")
    synchronized(staticLock) {
        Thread.sleep(1000)
        latestValue = input
    }
    println("finished function $input at ${System.currentTimeMillis()}")
}