直接上代码：
1. 第一种情况， 如果没有select{}， main 主线程不会等待coroutine运行，导致coroutine得不到机会运行。
You are requesting eventual scheduling (using the two go statements)
of two goroutines and then you exit main without giving the scheduler
a chance to do anything.
有了select， 程序正常运行。
package main import ( "fmt" "time" ) func main() { go func1() go func2() select{} } func func1() { for{ fmt.Println("here1") time.Sleep(10 * time.Minute) } } func func2() { for{ fmt.Println("here2") time.Sleep(10 * time.Minute) }} 2. coroutine有机会运行，但是会发生死锁， fatal error: all goroutines are asleep - deadlock!
The goroutine executing func1 exited, ditto for func2. The main goroutine is blocked with no hope to recover while no other goroutine can be scheduled.
package main import ( "fmt" //"time" ) func main() { go func1() go func2() select { } } func func1() { fmt.Println("here1") } func func2() { fmt.Println("here2") } 3. 第三种情况， 正常运行。
package main import ( "fmt" ) var c = make(chan int, 2) func main() { go func1() go func2() <-c <-c fmt.Println("ok") } func func1() { fmt.Println("here1") c <- 1 } func func2() { fmt.Println("here2") c <- 1 } 4. 实现上面的目的的另外一种方法：
var wg sync.WaitGroup var urls = []string{ "http://www.golang.org/", "http://www.google.com/", "http://www.somestupidname.com/", } for _, url := range urls { // Increment the WaitGroup counter. wg.Add(1) // Launch a goroutine to fetch the URL. go func(url string) { // Decrement the counter when the goroutine completes. defer wg.Done() // Fetch the URL. http.Get(url) }(url) } // Wait for all HTTP fetches to complete. wg.Wait()有疑问加站长微信联系（非本文作者）
