Go Concurrency Patterns

Production patterns for Go concurrency including goroutines, channels, synchronization primitives, and context management.

When to Use

• Building concurrent Go applications
• Implementing worker pools and pipelines
• Managing goroutine lifecycles and cancellation
• Debugging race conditions
• Implementing graceful shutdown

Concurrency Primitives

Go Concurrency Mantra: Don't communicate by sharing memory; share memory by communicating.

Quick Start

func main() {
    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()

    results := make(chan string, 10)
    var wg sync.WaitGroup

    for i := 0; i < 3; i++ {
        wg.Add(1)
        go func(id int) {
            defer wg.Done()
            select {
            case <-ctx.Done():
                return
            case results <- fmt.Sprintf("Worker %d done", id):
            }
        }(i)
    }

    go func() { wg.Wait(); close(results) }()

    for result := range results {
        fmt.Println(result)
    }
}

Pattern 1: Worker Pool

type Job struct {
    ID   int
    Data string
}

type Result struct {
    JobID  int
    Output string
    Err    error
}

func WorkerPool(ctx context.Context, numWorkers int, jobs <-chan Job) <-chan Result {
    results := make(chan Result)
    var wg sync.WaitGroup

    for i := 0; i < numWorkers; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for job := range jobs {
                select {
                case <-ctx.Done():
                    return
                default:
                    results <- Result{
                        JobID:  job.ID,
                        Output: fmt.Sprintf("Processed: %s", job.Data),
                    }
                }
            }
        }()
    }

    go func() { wg.Wait(); close(results) }()
    return results
}

// Usage
func main() {
    ctx, cancel := context.WithCancel(context.Background())
    defer cancel()