Go Context Example

main.go

package main

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

func main() {
        ctx := context.Background()
        go parentProcess(ctx)
        time.Sleep(1000 * time.Second)
}

func parentProcess(ctx context.Context) {
        childCtx, cancel := context.WithCancel(ctx)
        childCtx2, _ := context.WithCancel(childCtx)
        go childProcess(childCtx, "child1")
        go childProcess(childCtx2, "child2")
        // Cancel after 10 seconds
        time.Sleep(10 * time.Second)
        // childCtx2, which is derived from childCtx, also propagates the cancellation. childCtx2's cancelFunc must be called as well otherwise go vet yells at us
        cancel()
        // cancel after 10 seconds. cancelFunc is not called in this sample, but you have to explicitly call cancelFunc somewhere otherwise go vet yells at us
        ctxWithTimeout10, _ := context.WithTimeout(ctx, time.Second*10)
        go childProcess(ctxWithTimeout10, "with timeout")
}

func childProcess(ctx context.Context, prefix string) {
        for i := 1; i <= 1000; i++ {
                select {
                case <-ctx.Done():
                        fmt.Printf("%s: canceld \n", prefix)
                        return
                case <-time.After(1 * time.Second):
                        fmt.Printf("%s:%d sec..\n", prefix, i)
                }
        }
}