Kotlin 分块、异步和等待的奇怪行为

Question

I'm doing some code that involves a number of parallel requests in batchs from elements in a list and I'm facing a strange behaviour:

https://pl.kotl.in/joFkWgV13

It should display "holamundo" but sometimes this example prints "mundomundo" instead.

What I'm missing here?

Answer 1

The reason for this behavior is that the code inside async is not run immediately. It is only scheduled. The async block returns before the lambda is invoked. This is why the it inside async block always points to the ["world"] window and hence the final output is "mundomundo".

Take this example:

fun main() {
    runBlocking {
        var a = 1
        val deferred = async {
            println(a)
        }
        a++
        deferred.await()
    }
}

Playground
In this example the output will be 2 and not 1 because a++ is processed before the async lambda.