Golang 并发以及通道的使用方式

package main 
import (
 "fmt"
 "time"
)
 
func Foo(i int) {
 fmt.Printf("%d will sleep\n", i)
 time.Sleep(5 * time.Second)
 fmt.Printf("%d wake up\n", i)
}
 
func main() {
 for i := 0; i < 5; i++ {
 Foo(i)
 }
}

0 will sleep
0 wake up
1 will sleep
1 wake up
2 will sleep
2 wake up
3 will sleep
3 wake up
4 will sleep
4 wake up

package main
 
import (
 "fmt"
 "time"
) 
func Foo(i int) {
 fmt.Printf("%d will sleep\n", i)
 time.Sleep(5 * time.Second)
 fmt.Printf("%d wake up\n", i)
} 
func main() {
 for i := 0; i < 5; i++ {
 go Foo(i)
 } 
 time.Sleep(10 * time.Second)
}

package main 
import (
 "fmt"
 "time"
)
 
func Foo(i int, ch chan int) {
 fmt.Printf("%d will sleep\n", i)
 time.Sleep(5 * time.Second)
 fmt.Printf("%d wake up\n", i)
 ch <- 1
}
 
func main() {
 ch := make(chan int)
 
 for i := 0; i < 5; i++ {
 go Foo(i, ch)
 }
 
 count := 0
 for count < 5 {
 count += <-ch
 }
}

package main 
import (
 "fmt"
 "math/rand"
)
 
func Consumer(ch <-chan int, result chan<- int) {
 sum := 0
 for i := 0; i < 5; i++ {
 sum += <-ch
 }
 
 result <- sum
}
 
func Producer(ch chan<- int) {
 var num int
 for i := 0; i < 5; i++ {
 rand.Seed(20)
 num = rand.Intn(100)
 ch <- num
 }
}
 
func main() {
 ch := make(chan int)
 result := make(chan int)
 go Producer(ch)
 go Consumer(ch, result)
 
 fmt.Printf("result: %d\n", <-result)
}

func main() {
 // 示例1
 //通道是一个先进先出（FIFO）的队列
 channel := make(chan int,3)
 channel <- 1
 channel <- 2
 channel <- 3
 fmt.Printf("the first channel value is %v\n",<-channel)
 v := <- channel
 fmt.Printf("the first channel value is %v\n",v)
 fmt.Printf("the first channel value is %v\n",<-channel)
 // 报错：fatal error: all goroutines are asleep - deadlock!
 // fmt.Printf("the first channel value is %v\n",<-channel)
}

func main() {
 // 示例2
 channel := make(chan int,3)
 channel <- 1
 channel <- 2
 channel <- 3
 // 报错1：fatal error: all goroutines are asleep - deadlock!
 //channel <- 4
 fmt.Printf("the first channel value is %v\n",<-channel)
 v := <- channel
 fmt.Printf("the first channel value is %v\n",v)
 fmt.Printf("the first channel value is %v\n",<-channel)
 // 报错2：fatal error: all goroutines are asleep - deadlock!
 //fmt.Printf("the first channel value is %v\n",<-channel)
 // 示例3
 channel2 := make(chan int,0)
 go func() {
 time.Sleep(time.Second*5)
 v := <- channel2
 fmt.Printf("the value is %v\n",v)
 }()
 channel2 <- 1
 fmt.Print("the time is over\n")
}

func main() {
 // 示例4
 channel3 := make(chan int,2)
 channel3 <- 1
 channel3 <- 2
 close(channel3)
 // 报错3: panic: send on closed channel
 // channel3 <- 3
 // 报错4：panic: close of closed channel
 //close(channel3)
 // 示例5
 channel5 := make(chan int,2)
 channel5 <- 1
 channel5 <- 2
 v1,b1 := <- channel5
 fmt.Printf("v1:%v b1:%v\n",v1,b1)
 v2,b2 := <- channel5
 fmt.Printf("v2:%v b2:%v\n",v2,b2)
 close(channel5)
 v3,b3 := <- channel5
 fmt.Printf("v3:%v b3:%v\n",v3,b3)
 /*输出：
 v1:1 b1:true
 v2:2 b2:true
 v3:0 b3:false
 */
 // 示例6
 channel6 := make(chan int,2)
 channel6 <- 1
 channel6 <- 2
 v4,b4 := <- channel6
 fmt.Printf("v4:%v b4:%v\n",v4,b4)
 close(channel6)
 v5,b5 := <- channel6
 fmt.Printf("v5:%v b5:%v\n",v5,b5)
 /*输出：
 v4:1 b4:true
 v5:2 b5:true
 */
}