import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import kotlinx.coroutines.Dispatchers

val start by lazy { System.currentTimeMillis() }

fun log(TAG: String) {
    val relTime = System.currentTimeMillis() - start
    println("$TAG @${relTime}ms in ${Thread.currentThread()}")
}

fun main() {
    runBlocking {
        launch {
            log("Start #1")
            runBlocking {
                log("Before delay #1")
                delay(100)
                log("After delay #1")
            }
            log("Done #1")
        }
        launch {
            log("Start #2")
            runBlocking {
                log("Before delay #2")
                delay(300)
                log("After delay #2")
            }
            log("Done #2")
        }
    }
}

Start #1 @0ms in Thread[main @coroutine#2,5,main]
Start #2 @1ms in Thread[main @coroutine#3,5,main]
Before delay #1 @2ms in Thread[main @coroutine#4,5,main]
Before delay #2 @6ms in Thread[main @coroutine#5,5,main]
After delay #1 @105ms in Thread[main @coroutine#4,5,main]
After delay #2 @307ms in Thread[main @coroutine#5,5,main]
Done #2 @307ms in Thread[main @coroutine#3,5,main]
Done #1 @307ms in Thread[main @coroutine#2,5,main]

runBlocking

runBlocking

coroutineScope { … }

<http://Dispatchers.IO|Dispatchers.IO>

runBlocking { … }

then don't do it