How could I check if a singlethreaded coroutine context is currently executing or not?

What is your use case for it?

I want a single thread to which I queue tasks, and if a task is already executing I don't want to queue another task, rather, do something else like printing a message

Oh, I think that it’s completely wrong approach to queue coroutine tasks

yep makes sense

See more details here https://github.com/Kotlin/kotlinx.coroutines/blob/master/docs/shared-mutable-state-and-concurrency.md#actors