03-worker-pool

Worker Pool

It implements the worker pool. I combine generator and fan-in pattern to achieve it. Besides, I add a lot of <-ctx.Done() to make sure all goroutine will be closed, except main goroutine.

Refer Worker Pool Example Code.

go-concurrency-patterns/other/03-worker-pool/main.go

Lines 101 to 122 in fcce219

	func main() {
	wg := &sync.WaitGroup{} // for detecting worker all closed
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	jobs := genJobs(ctx)
	results := make([]<-chan int, workerSize)
	for i := 0; i < workerSize; i++ {
	wg.Add(1)
	results[i] = worker(ctx, i, jobs, wg)
	}
	flow := fanIn(ctx, results...)
	for data := range flow {
	log.Printf("Result is :%d", data)
	}
	wg.Wait()
	fmt.Printf("expected 1 goroutine, got goroutine: %d\n", runtime.NumGoroutine())
	}

You could call close() early by replacing L105 with time.AfterFunc(2*time.Second, cancel). You still see the got goroutine 1.