PublishSubject with Kotlin coroutines (Flow)

Flow is a cold asynchronous stream, just like an Observable.

All transformations on the flow, such as map and filter do not trigger flow collection or execution, only terminal operators (e.g. single) do trigger it.

The onEach method is just a transformation. Therefore you should replace it with the terminal flow operator collect. Also you could use a BroadcastChannel to have cleaner code:

private val channel = BroadcastChannel<Boolean>(1)

suspend fun someMethod(b: Boolean) {
    channel.send(b)
}

suspend fun observe() {
  channel
    .asFlow()
    .debounce(500)
    .collect {
        // value received
    }
}

_{Update: At the time the question was asked there was an overload of debounce with two parameters (like in the question). There is not anymore. But now there is one which takes one argument in milliseconds (Long).}