I've got a list of objects that have Deferred properties which produce some kind of reult, afteer result is produced, the Deferred is replaced by another (Completable)Deferred. Now I want to create a listener which will perform some action when any future is completed. I am trying to do so using

select

clause this way:

val job = launch {
            while (true) {
                select<Unit> {
                    stateHolder.forEach { state ->
                        state.future.onAwait {
                                // do something
                        }
                    }
                }
            }
        }

But it does not seem to enter the select clause even once. What am I doing wrong?

Did you try to debug?

Of course. I found it to be a some bizarre synchronization problem, which i did not expect to encounter in coroutines. Everything works fine if I introduce blocking sleep between state changes which are done from outside of coronations. Probably should use

Mutex

locks. In fact, I keep thinking that it should be simpler. All I need is to create an observable mutable state with coroutine based subscribers.

Coroutines do not solve syncronous problems if you have shared mutable states between threads, bit with coroutines you can use actors or other patterns to handle this

I do not have problems with concurrent state changes, the problem was with notifications. I finally solved it with

BroadcastChannel

. Everything seems to be working fin now.