原文:https://studygolang.com/topics/7050
go修改全局变量的问题
测试 goroutine 修改全局变量,有x y 两个全局函数,分别在两个 goroutine f1() 和 f2() 中修改(f1()修改x,f2()修改y),f2() 只多了一行sleep,为什么最终主 goroutine 打印y时,y的值一直是0?? 代码如下
package main import ( "fmt" "runtime" "time" ) var x, y int func main() { runtime.GOMAXPROCS(3) go f1() go f2() for { time.Sleep(time.Second * 1) fmt.Println("x:", x, "y", y) } } func f1() { for { x = x + 1 time.Sleep(time.Second * 1) } } func f2() { for { y = y + 1 } }
结果:
package main import ( "fmt" "runtime" "time" ) var x, y int func main() { fmt.Println(runtime.NumCPU()) runtime.GOMAXPROCS(3) x = 100 y = 33 go f1(&x) go f2(&y) for { time.Sleep(time.Second * 1) fmt.Println("x:", x, "y", y) } } func f1(x *int) { for { *x = *x + 1 time.Sleep(time.Second * 1) } } func f2(y *int) { for { *y = *y + 1 } }