003、GO之并发

package main

import "fmt"

func main() {
    c := make(chan bool)
    go func() {
        fmt.Println("hello")
        c <- true
    }()
    <-c
}

 1 package main
 2 
 3 import "fmt"
 4 
 5 func main() {
 6     c := make(chan bool)
 7     go func() {
 8         fmt.Println("hello")
 9         c <- true
10         close(c)//不手动关闭chan，会导致for循环无法结束，go所有协程都在等待导致死锁，从而崩溃
11     }()
12     for v :=range c {
13         fmt.Println("chan的值", v)
14     }
15 }

 1 package main
 2 
 3 import "fmt"
 4 
 5 func main() {
 6     c := make(chan bool, 1)//指定了大小，有缓存
 7     go func() {
 8         fmt.Println("hello")
 9         <-c
10     }()
11     c <- true//因为有缓存，读不到，则直接结束
12 }

 1 package main
 2 
 3 import (
 4     "fmt"
 5     "time"
 6 )
 7 
 8 func main() {
 9     now := time.Now()
10     defer fmt.Println("耗时不用函数", time.Now().Sub(now).Seconds())
11     defer func() {
12         fmt.Println("耗时用函数", time.Now().Sub(now).Seconds())
13     }()
14     
15     c := make(chan bool, 10)
16     for i := 0; i < 10; i ++ {
17         go hello(c, i)
18     }
19     for i := 0; i < 10; i++ {
20         <-c
21     }
22 }
23 
24 func hello(c chan bool, index int) {
25     fmt.Println("hello, ", index)
26     c <- true
27 }