Hands-On Design Patterns with Kotlin

Scheduler

This is another concept we discussed briefly in Chapter 8, Threads and Coroutines, in the Starting a coroutine section.

Remember how our launch() or async() could receive CommonPool?

Here's an example to remind you that you could specify it explicitly:

// Same as launch {}launch(CommonPool) {...}// Same as async {}val result = async(CommonPool) {...}

This CommonPool is a Scheduler design pattern in a bad disguise. Many async tasks may be mapped to the same Scheduler.

Run the following code:

val r1 = async(CommonPool) {    for (i in 1..1000) {        println(Thread.currentThread().name)        yield()    }}r1.await()

What is interesting is the fact that the same coroutine is picked up by different threads:

ForkJoinPool.commonPool-worker-2ForkJoinPool.commonPool-worker-3 ...