subscribeOn(Schedulers.io()) 不起作用但 subscribeOn(Schedulers.trampoline()) 起作用

Question

fun main() {
    Single.just("faefw")
        .subscribeOn(Schedulers.trampoline())
        .map {
            println("map in thread ${Thread.currentThread().name}")
        }
        .flatMap {
            return@flatMap Single.just(231).map {
                println("map in thread ${Thread.currentThread().name}")
                return@map it
            }
        }
        .subscribe({
            println(it)
        }, {
            println(it)
        })
}

打印出来：

map in thread main
map in thread main
231

但是

fun main() {
    Single.just("faefw")
        .subscribeOn(Schedulers.io())
        .map {
            println("map in thread ${Thread.currentThread().name}")
        }
        .flatMap {
            return@flatMap Single.just(231).map {
                println("map in thread ${Thread.currentThread().name}")
                return@map it
            }
        }
        .subscribe({
            println(it)
        }, {
            println(it)
        })
}

什么都不输出！

subscribeOn(Schedulers.computation()) 和 subscribeOn(Schedulers.newThread()) 也不行

为什么？

Answer 1

程序在代码有时间执行之前就退出了。在 subscribe

之后尝试睡眠或输入打印语句

fun main() {
    Single.just("faefw")
        .subscribeOn(Schedulers.io())
        .map {
            println("map in thread ${Thread.currentThread().name}")
        }
        .flatMap {
            return@flatMap Single.just(231).map {
                println("map in thread ${Thread.currentThread().name}")
                return@map it
            }
        }
        .subscribe({
            println(it)
        }, {
            println(it)
        })
    println("just subscribed in last statement!")
    Thread.sleep(500)
    println("exiting main thread...")
}

用蹦床输出是

map in thread main
map in thread main
231
just subscribed in last statement!
exiting main thread...

与其他在不同线程中执行“工作”的调度程序（如 .io() 和 .computation()）将有如下输出：

just subscribed in last statement!
map in thread RxComputationThreadPool-1
map in thread RxComputationThreadPool-1
231
exiting main thread...

PS。您可以将 io() 调度程序视为无界线程池，computation() 视为有界线程池。

subscribeOn(Schedulers.io()) 不起作用但 subscribeOn(Schedulers.trampoline()) 起作用

subscribeOn(Schedulers.io()) not working but subscribeOn(Schedulers.trampoline()) does

kotlin

rx-java

rx-java2