timeout and synchronization

main.go

package main

import (
	"context"
	"fmt"
	"math/rand"
	"time"
)

const timeout = time.Second
const routinesToStart = 10

var rng = rand.New(rand.NewSource(time.Now().Unix()))

func processDoubleAsync(ctx context.Context, id int) {
	go func(ctx context.Context) {
		ctx, cancel := context.WithTimeout(ctx, timeout)
		defer cancel()

		done := make(chan bool)

		go func() {
			process(ctx, id)
			done <- true
		}()

		select {
		case <-ctx.Done():
			fmt.Printf("error: processing timeout - %d\n", id)
			break
		case <-done:
			fmt.Printf("finished processing\n")
			return
		}
	}(ctx)
}

func processAsync(ctx context.Context, id int) {
	ctx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	done := make(chan bool)

	go func() {
		process(ctx, id)
		done <- true
	}()

	select {
	case <-ctx.Done():
		fmt.Printf("error: processing timeout - %d\n", id)
		break
	case <-done:
		fmt.Printf("finished processing\n")
		return
	}
}

func process(ctx context.Context, id int) {
	fmt.Printf("processing %d started...\n", id)

	sleepTime := time.Duration(rng.Int31n(2000)) * time.Millisecond
	time.Sleep(sleepTime)

	fmt.Printf("%d ended after %s\n", id, sleepTime)
}

func main() {
	ctx := context.Background()

	for i := 0; i < routinesToStart; i++ {
		processDoubleAsync(ctx, i)
	}

	time.Sleep(time.Second * 30)
}