Another question about coroutines: in the tutorial...

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[Dias]

Another question about coroutines: in the tutorial there is an example where there process waits for coroutine to finish computation before it gets cancelled

fun main(args: Array<String>) = runBlocking<Unit> {
    val startTime = System.currentTimeMillis()
    val job = launch {
        var nextPrintTime = startTime
        var i = 0
        while (i < 5) { // computation loop, just wastes CPU
            // print a message twice a second
            if (System.currentTimeMillis() >= nextPrintTime) {
                println("I'm sleeping ${i++} ...")
                nextPrintTime += 500L
            }
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

but the code below that

fun main(args: Array<String>) = runBlocking<Unit> {
    val job = launch {
        try {
            repeat(1000) { i ->
                println("I'm sleeping $i ...")
                delay(500L)
            }
        } finally {
            println("I'm running finally")
        }
    }
    delay(1300L) // delay a bit
    println("main: I'm tired of waiting!")
    job.cancelAndJoin() // cancels the job and waits for its completion
    println("main: Now I can quit.")
}

is not being awaited to finish it’s job before cancellation

[Martin Devillers]

The difference is that delay handles cancellation. In the first example, there’s no delay within the launch, there’s just a while loop which runs continuously because its condition is updated only once a given time has updated. In the other examples, you use a delay statement, so the cancel applied to job has an immediate effect.

[Dias]

oh indeed, thank you, that explains it