英文:
main exiting to soon, due to goroutine
问题
我正在尝试重新实现/修改此帖子的第二个评论中的代码。
我想要多个goroutine从堆栈中弹出元素（只要堆栈中还有元素），并且另一个函数来接收它们。
以下是在playground中的代码：链接
func pop(list *[]int, c chan int) {
if len(*list) != 0 {
result := (*list)[0]
*list = (*list)[1:]
fmt.Println("about to send ", result)
c <- result
} else {
return
}
}
func receiver(c chan int) {
result := <-c
fmt.Println("received ", result)
}
var list = []int{1, 2, 3}
func main() {
fmt.Println("Main")
c := make(chan int)
go pop(&list, c)
go pop(&list, c)
receiver(c)
fmt.Scan()
}
如果我将receiver(c)改为一个goroutine，只会打印出"Main"，并且程序将在不等待Scan()函数的情况下退出。即使添加time.Sleep(2)也无法阻止程序退出。
为什么我的程序在没有任何输入的情况下退出？
英文:
I am trying to reimplement / modify the code of the second comment of this post.
I would like multiple go routines to pop elements from the stack (as long as the stack contains something), and another function to catch them.
func pop(list *[]int, c chan int) {
if len(*list) != 0 {
result := (*list)[0]
*list = (*list)[1:]
fmt.Println("about to send ",result)
c <- result
} else {return}
}
func receiver (c chan int){
result := <- c
fmt.Println("received ", result)
}
var list = []int{1, 2, 3}
func main() {
fmt.Println("Main")
c := make(chan int)
go pop (&list, c)
go pop (&list,c)
receiver(c)
fmt.Scan()
If I make receiver(c) a go routine, only "Main" will be printed, and the program will exit without waiting for the Scan() function. Even adding a time.Sleep(2) won't prevent the program from exiting.
Why is my program exiting without any input?
答案1
得分: 2
Scan函数在没有参数的情况下不会阻塞。
请注意，即使给Playground传递参数，它也不会在IO上阻塞，比如以下代码：
var i int
fmt.Scan(&i)
即使你检查它返回的error值（第二个返回值），你会发现它报告了error: EOF，但这个示例在Playground之外会阻塞。
编辑：如果你想要在输入时阻塞而不创建一个虚拟变量，可以使用Scanln函数，但在Playground上仍然会失败。
英文:
Scan will not block if given zero arguments.
Note that the Playground will not block on IO even if you give it an argument, the code
var i int
fmt.Scan(&i)
Also will fail to block, if you check the error value it returns (the second return value), which you should, you'll see it reports error: EOF.
(Though that sample will block outside the Playground).
Edit: If you want to block on input without making a dummy variable, use Scanln, though it still will fail on the Playground.
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