响应式subscribeOn改变scheduler无法输出

[MIvan]

下面的代码运行没有任何输出，让我感到很奇怪，但是去掉.subscribeOn(Schedulers.computation()这句代码之后就可以输出，求高人指点一二，官方文档也没有看到关于.subscribeOn(Schedulers.computation()的特殊之处

Observable observable = Observable.<String>create(subscriber -> {
                    try {
                        subscriber.onNext("1");
                        System.out.println(" current thread is " + Thread.currentThread().getName());
                        Thread.sleep(100);
                        subscriber.onNext("2");
                        Thread.sleep(300);
                        subscriber.onNext("3");
                        Thread.sleep(1000);
                        subscriber.onNext("4");
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
        );

        observable.subscribeOn(Schedulers.computation()).timeInterval().observeOn(Schedulers.computation()).subscribe(n -> System.out.println(((TimeInterval) n).getIntervalInMilliseconds()
                        + "   value is  " + ((TimeInterval) n).getValue()),
                e -> System.out.println("onerror " + e),
                () -> System.out.println("oncomplete "));