Kotlin 海峡没有结束

我是Kotlin Channel的新手.

下面的代码是produce扩展函数的实践代码，它返回ReceiveChannel.对于repeat(10)的每一次迭代，用新的ReceiveChannel重新分配变量cur.这就是我在filter扩展函数中调用cancel()方法的原因.

我本以为这会正常结束，但事实并非如此:

fun CoroutineScope.numbersFrom(start: Int) = produce<Int> {
    var x = start
    while (true) send(x++) // infite stream of integers from start
}

fun CoroutineScope.filter(numbers: ReceiveChannel<Int>, prime: Int) = produce<Int> {
    for (x in numbers) if (x % prime != 0) send(x)
    numbers.cancel() // Canceled here
}

fun main() {
    runBlocking {
        var cur = numbersFrom(2) // infinitely send numbers...
        repeat(10) {
            val prime = cur.receive() // retrieve only one element
            println(prime)
            cur = filter(cur, prime) // new Receiver
        }
        cur.cancel() // Canceled here
    }
}

我try 了以下几种方法，但得到了这样的例外:

线程"main"中出现异常kotlinx.coroutines.JobCancerationException:BlockingCoroutine已取消；JOB=BlockingCoroutine{取消}@26a7b76d

fun CoroutineScope.numbersFrom(start: Int) = produce<Int> {
    var x = start
    while (true) send(x++) // infite stream of integers from start
}

fun CoroutineScope.filter(numbers: ReceiveChannel<Int>, prime: Int) = produce<Int> {
    for (x in numbers) if (x % prime != 0) send(x)
    numbers.cancel()
}

fun main() {
    runBlocking {
        var cur = numbersFrom(2) // infinitely send numbers...
        repeat(10) {
            val prime = cur.receive() // retrieve only one element
            println(prime)
            cur = filter(cur, prime) // new Receiver
        }
        cur.cancel()
        coroutineContext.cancel()
    }
}

此外，此代码自然结束，因为它取消了所有子代协程:

fun CoroutineScope.numbersFrom(start: Int) = produce<Int> {
    var x = start
    while (true) send(x++) // infite stream of integers from start
}

fun CoroutineScope.filter(numbers: ReceiveChannel<Int>, prime: Int) = produce<Int> {
    for (x in numbers) if (x % prime != 0) send(x)
    numbers.cancel()
}

fun main() {
    runBlocking {
        var cur = numbersFrom(2) // infinitely send numbers...
        repeat(10) {
            val prime = cur.receive() // retrieve only one element
            println(prime)
            cur = filter(cur, prime) // new Receiver
        }
        coroutineContext.cancelChildren()
    }
}

有没有不用coroutineContext.cancelChildren()就能自然完成的方法？