运行线程一定时间-在被杀死之前

Question

How do I run 10 threads, for 30 seconds each, and then return to the program execution? For example, I want

1. 10 threads to be spawned and ran for 30 seconds.
2. Then all threads killed
3. Then second() to run (i.e. after all threads have finished executing)

So far I have the following however, when I do this, the threads (obviously) keep executing and CPU usage remains at 100% after 30s:

func main(){
    for i := 0; i < 10; i++{
        go thread()
    }
    time.Sleep(30 * time.Second)
    second()
}

func thread() {
    for {
        // Do stuff
    }
}

Answer 1

You could use Golang context. Here's some of my code when I was learning it.

package main

import (
    "fmt"
    "log"
    "time"

    "golang.org/x/net/context"
)

func main() {
    someHandler()
}

func someHandler() {
    //Create a new context with a timeout duration of six seconds. You also get a cancel function you can call early. 
    //You can also have context end at a certain time, instead of a timeout
    ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(6))

    for i := 0; i < 5; i++ {
        go doStuff(ctx, i)
    }

    select {
    case <- ctx.Done():
        log.Println("Got a cancel request")
        return
    case <-time.After(time.Second * time.Duration(5)):
        //Here I'm actually ending it earlier than the timeout with cancel().
        log.Println("Timed out")
        cancel()
    }

}

func doStuff(ctx context.Context, num int) {
    for {
        select {
        case <-ctx.Done():
            fmt.Println("Done working")
            return
        default:
            fmt.Println("go", num, "working")
        }
        time.Sleep(time.Second)
    }
}

Outputs:

$ go run app.go 
go 0 working
go 4 working
go 2 working
go 3 working
go 1 working
go 1 working
go 0 working
go 4 working
go 3 working
go 2 working
go 0 working
go 4 working
go 2 working
go 1 working
go 3 working
go 4 working
go 3 working
go 0 working
go 2 working
go 1 working
go 3 working
go 4 working
go 1 working
go 0 working
go 2 working
2016/10/01 23:25:23 Timed out