SubscribeOnExample4.kt

fun debugSubscribeOn(): Disposable =
  Observable.just(1)
    .doOnNext {
      println(Thread.currentThread().name) // RxCachedThreadScheduler-1
    }
    .subscribeOn(Schedulers.io())
    .flatMap {
      println(Thread.currentThread().name) // RxCachedThreadScheduler-1
      Observable.just(it)
        .doOnNext {
          println(Thread.currentThread().name) // RxCachedThreadScheduler-1
        }
    }
    .subscribeOn(Schedulers.newThread())
    .doOnNext {
      println(Thread.currentThread().name) // RxCachedThreadScheduler-1
    }
    .subscribe()