Setting a custom pool of threads by using the asCoroutineDispatcher function on Java’s ExecutorService.

Coroutines.kt

import kotlinx.coroutines.*
import java.util.concurrent.Executors

suspend fun suspendTask1() {
    println("Start task1 | Thread ${Thread.currentThread()}")
    yield()
    println("End task1 | Thread ${Thread.currentThread()}")
}

suspend fun suspendTask2() {
    println("Start task2 | Thread ${Thread.currentThread()}")
    yield()
    println("End task2 | Thread ${Thread.currentThread()}")
}

fun main() {
    Executors.newSingleThreadExecutor().asCoroutineDispatcher().use { context ->
        println("Start main")

        runBlocking {
            launch(context) { suspendTask1() }
            launch { suspendTask2() }
            println("Called task1 and task2 from ${Thread.currentThread()}")
        }

        println("End main")
    }
}