Coroutines and deadlocks

[fvasco]

@Loke

What is the FJP dispatcher?

The Java ForkJoinPool Executor.

@Loke

I assumed that the default dispatching mechanism was similar to how processes work in Erlang,

Where did you find that?

@Loke

you can fire off any number you want and it’ll be scheduled appropriately

Yes, but you have to avoid any blocking function, like runBlocking.

@Loke

On their own they are perfectly reasonable

None of both is reasonable.
If you block a shared, limited pool supposing it contains always enough Thread to execute your code then you are wrong.

@Loke

This is what Erlang would do in this case.

But your platform is JVM, not BEAM.

@Loke

The Kotlin coroutine documentation suggests that I can treat coroutines as lightweight threads that work like threads but are dispatched on a smaller number of actual operating system threads.

You are right, so you should care to not block none of Dispatcher.Default’s Thread, never, and consider Dispatcher.IO for blocking invocation.

runBlocking is a bridge function, you should use it if and only if you must block the thread.
My suggestion for you: use Dispatcher.Default thinking that it contains only one (or two) thread for the whole application.