Trying to understand why it's never completed: ```...

# coroutines

[ghedeon]

Trying to understand why it's never completed:

fun main(){
    runBlocking{
    	foo().consumeEach{ println(it) }
    }
}

suspend fun foo(): ReceiveChannel<Int> = coroutineScope {
    produce<Int>{
		channel.send(42)
               channel.close()
    }
}

[marstran]

You are creating a new coroutine scope inside foo which will wait until all child coroutines are completed. However, the produce-coroutine will never complete because it suspends when you send 42 (because it's default capacity is 0).

[marstran]

It will work if you change your foo function to this:

fun CoroutineScope.foo(): ReceiveChannel<Int> = produce<Int>{
    channel.send(42)
    channel.close()
}

[marstran]

That will make you reuse the scope created by runBlocking.

[ghedeon]

yeah, that's how I'm doing it now. I just somehow assumed that if runBlocking{ produce{} } works, then runBlocking{ coroutineScope{ produce{} } } will work as well, because coroutineScope inherits the parent's scope...

[gildor]

Empty will also work, but if you add send it will suspend forever (something like deadlock)

[ghedeon]

got it. coroutineScope is suspended and send as well, so they block each other.

[gildor]

Yes, coroutineScope waits all child coroutines