Can someone help me understand why I cannot replace

awaitAll(one, two)

by

one.await(); two.await()

in this code?

What happens when you do it?

it will hangs

it’s a tricky place and we don’t yet decided how to design it 🙂 You have three coroutines:

foo

,

one

and

two

.

async

does not cancel its parent.

foo

is waiting for

one

(which sleeps forever), while

two

already failed, but this exception is not delivered, because no one called

await

on it. Complexity behind

awaitAll

implementation is exactly to resolve this problem

ah... of course it makes sense! Thank you @Vsevolod Tolstopyatov [JB]

You are welcome. The first thing which comes to mind is to cancel parent when

async

fails, but then in

try {
async { throw MyException() }.await()
} catch (e: MyException) {
}

catch

block won’t be executed because cancellation throws

CancellationException

🙂

huh, this is a little confusing. Is there a good article or any documentation that explains this more? Just trying to understand a little better….

@codyoss https://github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md + all public API is documented

ah thanks, It has been a while since I have looked at that readme. Seems like it has gotten some love recently. Thanks!