1. 有缓冲的channel
   
2. 举个例子

package mainimport ("fmt""time"
)func main() {c := make(chan int,3) //带有缓冲的 channelfmt.Println("len(c) =",len(c),",cap(c)",cap(c))go func() {defer fmt.Println("子go程结束")for i :=0; i<3; i++ {c <- ifmt.Println("子go程正在进行,发送的元素=",i,"len(c)=",len(c),",cap(c)=",cap(c))}}()time.Sleep(2* time.Second)for i :=0; i<3 ;i++  {num := <-c  //从c中接收数据，并赋值给numfmt.Println("num= ",num)}fmt.Println("main 结束")}

3. 当改为4个元素的时候，结果如下图所示：

package mainimport ("fmt""time"
)func main() {c := make(chan int,3) //带有缓冲的 channelfmt.Println("len(c) =",len(c),",cap(c)",cap(c))go func() {defer fmt.Println("子go程结束")for i :=0; i < 4; i++ {c <- ifmt.Println("子go程正在进行,发送的元素=",i,"len(c)=",len(c),",cap(c)=",cap(c))}}()time.Sleep(2* time.Second)for i :=0; i < 4 ;i++  {num := <-c  //从c中接收数据，并赋值给numfmt.Println("num= ",num)}fmt.Println("main 结束")}