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| package main | |
| import ( | |
| "fmt" | |
| "sync" | |
| ) | |
| func main() { | |
| list := []int{0, 1, 2, 3, 4} | |
| sizes := make(chan int) | |
| var wg sync.WaitGroup | |
| for e := range list { | |
| wg.Add(1) | |
| go func(e int) { | |
| defer wg.Done() | |
| sizes <- e | |
| }(e) | |
| } | |
| go func() { | |
| wg.Wait() | |
| close(sizes) | |
| }() | |
| var total int | |
| for num := range sizes { | |
| total += num | |
| } | |
| fmt.Println(total) | |
| } |
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| package main | |
| import ( | |
| "fmt" | |
| "time" | |
| ) | |
| func main() { | |
| var ch = make(chan string, 2) | |
| go func() { | |
| for i := 0; i < 5; i++ { | |
| time.Sleep(500 * time.Millisecond) | |
| ch <- "hello" | |
| } | |
| close(ch) | |
| }() | |
| for recv := range ch { | |
| fmt.Println(recv) | |
| } | |
| } | |
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| package main | |
| import ( | |
| "fmt" | |
| "os" | |
| "time" | |
| ) | |
| func main() { | |
| // select是一种多路复用技术，就像POSIX接口里的select可以同时对多个文件描述符进行监控一样，go提供的select可以同时对多个channel进行监控，实现并发接收。当多个case里的channel同时有数据ready的时候，select会随机选择一个case进行处理。 | |
| // 需要注意的是，range操作可以在channel关闭后自动退出，而select不会。所以在用for循环搭配select实现轮询时，select的case语句中必须显示的判断channel是否已经关闭，并做相应的处理，否则select每次从处于closed状态的channel中取出空值，并且继续执行case语句包含的body，程序的运行就可能与期望不一致。 | |
| var ch = make(chan string, 2) | |
| go func() { | |
| for i := 0; i < 5; i++ { | |
| time.Sleep(1000 * time.Millisecond) | |
| ch <- "hello" | |
| } | |
| close(ch) | |
| }() | |
| for { | |
| select { | |
| case recv, ok := <-ch: | |
| if !ok { | |
| os.Exit(0) | |
| } | |
| fmt.Println(recv) | |
| } | |
| } | |
| } |
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| package main | |
| import ( | |
| "fmt" | |
| "time" | |
| "math/rand" | |
| ) | |
| func main() { | |
| ch := make(chan string) | |
| count := 3 | |
| for index := 0; index < count; index++ { | |
| go func() { | |
| time.Sleep(time.Duration(rand.Intn(200)) * time.Millisecond) | |
| ch <- "hello" | |
| }() | |
| } | |
| for index := 0; index < count; index++ { | |
| fmt.Println(<-ch) | |
| } | |
| time.Sleep(time.Duration(rand.Intn(5000)) * time.Millisecond) | |
| } |
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| package main | |
| import ( | |
| "fmt" | |
| "strconv" | |
| "math/rand" | |
| "time" | |
| ) | |
| type Message struct { | |
| Id int | |
| Name string | |
| } | |
| func main() { | |
| messages := make(chan Message, 100) | |
| result := make(chan error, 100) | |
| // 创建任务处理Worker | |
| for i := 0; i < 3; i ++ { | |
| go worker(i, messages, result) | |
| } | |
| total := 0 | |
| // 发布任务 | |
| for k := 1; k <= 10; k ++ { | |
| messages <- Message{Id: k, Name: "job" + strconv.Itoa(k)} | |
| total += 1 | |
| } | |
| close(messages) | |
| // 接收任务处理结果 | |
| for j := 1; j <= total; j ++ { | |
| res := <-result | |
| if res != nil { | |
| fmt.Println(res.Error()) | |
| } | |
| } | |
| close(result) | |
| } | |
| func worker(worker int, msg <-chan Message, result chan<- error) { | |
| // 从通道 chan Message 中监听&接收新的任务 | |
| for job := range msg { | |
| fmt.Println("worker:", worker, "msg: ", job.Id, ":", job.Name) | |
| // 模拟任务执行时间 | |
| time.Sleep(time.Second * time.Duration(RandInt(1, 3))) | |
| // 通过通道返回执行结果 | |
| result <- nil | |
| } | |
| } | |
| func RandInt(min, max int) int { | |
| rand.Seed(time.Now().UnixNano()) | |
| return min + rand.Intn(max-min+1) | |
| } |
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| package main | |
| import ( | |
| "fmt" | |
| "sync" | |
| "time" | |
| ) | |
| func main() { | |
| var mutex sync.Mutex | |
| wait := sync.WaitGroup{} | |
| fmt.Println("Locked") | |
| mutex.Lock() | |
| for i := 1; i <= 3; i++ { | |
| wait.Add(1) | |
| go func(i int) { | |
| fmt.Println("Not lock:", i) | |
| mutex.Lock() | |
| fmt.Println("Lock:", i) | |
| time.Sleep(time.Second) | |
| fmt.Println("Unlock:", i) | |
| mutex.Unlock() | |
| defer wait.Done() | |
| }(i) | |
| } | |
| time.Sleep(time.Second) | |
| fmt.Println("Unlocked") | |
| mutex.Unlock() | |
| wait.Wait() | |
| } |
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