For Kai - It's relatively simple, and handles a few useful cases (ctrl+c, kind of graceful shutdown)

simpleconcurrent.go

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/signal"
	"strconv"
	"sync"
	"time"
)

const (
	numWorkers = 4
)

// TestJob is something we need to process
type TestJob struct {
	ID string `json:"id"`
}

func main() {

	ctx, cancel := context.WithCancel(context.Background())
	jobs := make(chan *TestJob)
	wg := &sync.WaitGroup{}
	wg.Add(numWorkers)

	for i := 0; i < numWorkers; i++ {
		go runWorker(ctx, jobs, wg)
	}

	go listenForSignals(cancel)

outer:
	for i := 0; i < 100; i++ {
		jobID := strconv.Itoa(i)
		select {
		case jobs <- &TestJob{jobID}:
		case <-time.After(1 * time.Second):
			break outer
		}
	}

	close(jobs)
	wg.Wait()
}

func listenForSignals(cancel context.CancelFunc) {
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	<-c
	cancel()
}

func runWorker(ctx context.Context, jobs chan *TestJob, wg *sync.WaitGroup) {
	defer wg.Done()
	defer fmt.Println("worker stopped")
	for {
		select {
		case <-ctx.Done():
			return
		case job, ok := <-jobs:
			if !ok {
				return
			}
			doSomeWork(job)
		}
	}
}

func doSomeWork(job *TestJob) {
	time.Sleep(500 * time.Millisecond)
	_, err := fmt.Println(job.ID)
	if err != nil {
		log.Println(err)
	}
}