coroutines on the jvm, is there some kind of underlying executor service that can be grabbed?

and yes,

Dispatchers.Default.asExecutorService()

dubious, basically I wrote a client that takes an ExecutorService (or provides a default) and now they’ve got +12 threads because it’s used inside of the threads spawned for coroutines. Anyways thanks that’s superb information and probably a really easy way to fix their problem