Hands-On Design Patterns with Kotlin

Starting coroutines

We've already seen how to start a new thread in Kotlin. Now let's start a new coroutine instead.

We'll create almost the same example we did with threads. Each coroutine will increment some counter, sleep for a while to emulate some kind of IO, and then increment it again:

val latch = CountDownLatch(10_000)val c = AtomicInteger()val start = System.currentTimeMillis()for (i in 1..10_000) {    launch(CommonPool) {        c.incrementAndGet()        delay(100)        c.incrementAndGet()        latch.countDown()    }}latch.await(10, TimeUnit.SECONDS)println("Executed ${c.get() / 2} coroutines in ${System.currentTimeMillis() - start}ms")

The first way of starting a new coroutine is by using the launch() function. Again, note that this is simply another function ...