3.1 go context code sample

context.WithCancel
 returns two associated objects, CTX and cancel, cancel call to send a null struct ctx, ctx once receiving the object to terminate the execution goroutine;
CTX is thread safe, it can be simultaneously transmitted to the plurality goroutine, triggering cancel, cancel the execution of all goroutine

package main

import (
    "context"
    "fmt"
    "time"
)

func testContext(){
    ctx,cancel := context.WithCancel(context.Background())
    go d1(ctx)
    go d2(ctx)
    
    time.Sleep(7*time.Second)
    cancel()
}

func d1(ctx context.Context){
    i:=0
    for {
        time.Sleep(1*time.Second)
        i++
        select {
            case <- ctx.Done():
                fmt.Println("d1 over")
                return
                
            default:
                fmt.Println("d1 ",i)
        }
    }
}

func d2(ctx context.Context){

    fmt.Println("d2 start")
    <- ctx.Done()
    fmt.Println("d2 over")
}

func main(){
    testContext()
    fmt.Println("main over")
}

Export

d2 start
d1  1
d1  2
d1  3
d1  4
d1  5
d1  6
main over