kotlin - 在runBlocking中使用coroutineScope有什么效果？

在 kotlin 协程 doc 中，它解释了“runBlocking 和 coroutineScope 之间的区别”:

我不太明白，示例代码显示

import kotlinx.coroutines.*

fun main() = runBlocking { // this: CoroutineScope
launch {
    delay(200L)
    println("+++Task from runBlocking")
}

coroutineScope { // Creates a coroutine scope
    launch {
        delay(500L)
        println("+++Task from nested launch")
    }

    delay(100L)
    println("+++ Task from coroutine scope") // This line will be printed before the nested launch
}

println("+++ Coroutine scope is over") // This line is not printed until the nested launch completes
}

日志:

2019-05-16 10:47:45.107 12239-12239 +++ before enter runBlocking{}
2019-05-16 10:47:45.219 12239-12239 +++ Task from coroutine scope
2019-05-16 10:47:45.320 12239-12239 +++ Task from runBlocking
2019-05-16 10:47:45.620 12239-12239 +++ Task from nested launch
2019-05-16 10:47:45.621 12239-12239 +++ ---after exit runBlocking{}

并且 +++ Task from nested launch 按预期显示在 +++ Task from runBlocking 之后，因为它有 500L 延迟。
但是如果在 launch 块之后添加一些其他的 coroutineScop{} 构建器，结果是令人困惑的。
这里在 launch 之后添加了两个 coroutineScop{}，其中有 30L 和 100L 延迟。
我期待看到 30L 延迟的日志应该在 300L 内部的 coroutineScop{} 延迟日志之前显示，但它在 launch 内部完成所有 coroutineScop{} 之后显示

fun testCoroutines() {
Log.e("+++", "+++ enter testCoroutines_3")
runBlocking {
    launch {
        println("+++ start Task from runBlocking, with 200L delay")
        delay(200L)
        println("+++ end Task from runBlocking, with 200L delay")
    }

    launch {
        println("+++ start Task from runBlocking, with 50L delay")
        delay(50L)
        println("+++ end Task from runBlocking, with 50L delay")
    }

    launch {
        println("+++ start Task from runBlocking, with 70L delay")
        delay(70L)
        println("+++ end Task from runBlocking, with 70L delay")
    }

    coroutineScope {
        println("+++ enter Task from coroutineScope")
        // Creates a coroutine scope
        launch {
            Log.v("+++", "+++ === start Task from nested launch, 500L")
            delay(500L)
            Log.v("+++", "+++ --- end Task from nested launch, 500L")
        }

        delay(100L)
        println("+++ in Task from coroutineScope after delay(100L)")

        launch {
            Log.v("+++", "+++ === start Task from nested launch, 300L")
            delay(300L)
            Log.v("+++", "+++ --- end Task from nested launch, 300L")
        }

        println("+++ --- exit Task from coroutine scope") // This line will be printed before the nested launch
    }

    launch {
        println("+++ start Task from runBlocking, with 30L delay")
        delay(30L)
        println("+++ end Task from runBlocking, with 30L delay")
    }

    launch {
        println("+++ start Task from runBlocking, with 100L delay")
        delay(100L)
        println("+++ end Task from runBlocking, with 100L delay")
    }

}

Log.e("+++", "--- exit  testCoroutines_3 scope is over") // This line is not printed until the nested launch completes

}

日志:

10:35:05.819 4657-4657 +++ enter testCoroutines_3
10:35:05.828 4657-4657 +++ enter Task from coroutineScope
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 200L delay
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 50L delay
10:35:05.833 4657-4657 +++ start Task from runBlocking, with 70L delay
10:35:05.834 4657-4657 +++ === start Task from nested launch, 500L
10:35:05.885 4657-4657 +++ end Task from runBlocking, with 50L delay
10:35:05.905 4657-4657 +++ end Task from runBlocking, with 70L delay
10:35:05.932 4657-4657 +++ in Task from coroutineScope after delay(100L)
10:35:05.933 4657-4657 +++ --- exit Task from coroutine scope
10:35:05.935 4657-4657 +++ === start Task from nested launch, 300L
10:35:06.034 4657-4657 +++ end Task from runBlocking, with 200L delay
10:35:06.235 4657-4657 +++ --- end Task from nested launch, 300L
10:35:06.334 4657-4657 +++ --- end Task from nested launch, 500L
10:35:06.335 4657-4657 +++ start Task from runBlocking, with 30L delay
10:35:06.335 4657-4657 +++ start Task from runBlocking, with 100L delay
10:35:06.366 4657-4657 +++ end Task from runBlocking, with 30L delay
10:35:06.436 4657-4657 +++ end Task from runBlocking, with 100L delay
10:35:06.437 4657-4657--- exit  testCoroutines_3 scope is over

认为至少 +++ start Task from runBlocking, with 30L delay 应该在 +++ === start Task from nested launch, 500L 之后和 +++ end Task from runBlocking, with 50L delay 之前更早地出现，但它没有并且在 launch 完成所有 +++ --- end Task from nested launch, 500L 之后才出现。coroutineScope 在 coroutines 块中做了什么？
(我正在测试使用 android 应用程序，单击按钮调用 testCoroutines )

最佳答案

对于 runBlocking 和 coroutineScope 来说，在它们中启动的所有协程完成之前它们不会完成。

注意区分“直到”未完成”和“阻塞调用线程直到”。 runBlocking 是唯一一个做后者的人。

关于kotlin - 在runBlocking中使用coroutineScope有什么效果？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/56171739/