Are Kotlin suspend functions blocking?

Question

Code:

suspend fun main() {
    println("main start")
    f1()
    println("main end")
}

suspend fun f1() {
    println("f1 start")
    delay(2_000)
    println("f1 end")
}

Actual Output:

main start
f1 start
f1 end
main end

My expected output

main start
f1 start
main end
f1 end

Does this mean suspend functions are blocking unlike JS?

Answer 1

That is the default behavior read more about suspending functions here, if you want to run f1 asynchronously you have to use async as:

suspend fun main() {
    withContext(Dispatchers.Main) {
        println("main start")//Run in main
        val getF1 = async(Dispatchers.IO) { f1() } // Run f1 in IO
        println("main end") // Run in main
        println(getF1.await())//Run in main
    }
}

suspend fun f1() : String {
    println("f1 start")
    delay(2_000)
    println("f1 end")
    return "f1 result"
}