您没有任何内容可以显式同步两个goroutine的顺序。如果运行足够的时间，您将看到调用以
fmt.Println不同的顺序进行打印。当执行goroutine时，由于它们是并发操作，因此无法保证它们将何时执行和/或完成。您需要使用各种标准库程序包或通道本身来同步并发运行的goroutine的执行。
例如（通过利用渠道的封锁性，您可以执行以下操作）：
func main() { c := make(chan int) go sum([]int{1, 2, 3}, c) //use the channel to block until it receives a send x := <-c fmt.Println(x) //then execute the next routine go sum([]int{4, 5, 6}, c) x = <-c fmt.Println(x)}另一个示例（显然不那么实用，但是在这里查看其他常见的go同步功能），您可以引入一个等待组和一个通道范围：
func sum(a []int, c chan int, wg *sync.WaitGroup) { defer wg.Done() fmt.Println("summing: ", a) total := 0 for _, v := range a { total += v } //fmt.Println("send to c",total) c <- total // send total to c}func main() { c := make(chan int) wg := new(sync.WaitGroup) //concurrently call the concurrent calls to sum, allowing execution to continue to the range of the channel go func() { //increment the wait group, and pass it to the sum func to decrement it when it is complete wg.Add(1) go sum([]int{1, 2, 3}, c, wg) //wait for the above call to sum to complete wg.Wait() //and repeat... wg.Add(1) go sum([]int{4, 5, 6}, c, wg) wg.Wait() //all calls are complete, close the channel to allow the program to exit cleanly close(c) }() //range of the channel for theSum := range c { x := theSum fmt.Println(x) }}
