Go, Together: визуальный гид по конкурентности в Go

var mu sync.Mutex
count := 0

func increment() {
    mu.Lock()          // enter
    count++            // protected
    mu.Unlock()        // leave
}

sem := make(chan struct{}, 3)

for _, job := range jobs {
    sem <- struct{}{}   // acquire
    go func() {
        defer func() { <-sem }() // release
        work(job)
    }()
}

jobs := make(chan int, 3)

go func() {
    for i := 1; i <= 5; i++ {
        jobs <- i        // send
    }
    close(jobs)       // no more sends
}()

for job := range jobs { work(job) }

select {
case result := <-apiResults:
    handle(result)
case event := <-events:
    dispatch(event)
case <-time.After(2 * time.Second):
    return errors.New("timeout")
}