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GOROUTINES

Core Concept: Goroutines are lightweight, independently executing functions managed by the Go runtime.

Why It Matters​

Enable concurrent programming with minimal overhead. Thousands of goroutines can run simultaneously. Core feature of Go.

When to Use​

✅ Use when:

  • I/O-bound operations (network, file)
  • Independent tasks can run concurrently
  • Need to handle multiple requests simultaneously
  • Background processing

❌ Don't use when:

  • Sequential operations required
  • Shared state without synchronization
  • Uncertain about race conditions

vs Java Threads​

Java ThreadsGo Goroutines
~1MB stack~2KB stack (grows as needed)
OS-managedGo runtime-managed
Heavy creation costCheap creation
Thread pools neededCreate freely
DANGER

Always ensure goroutines can exit. Use context for cancellation to prevent goroutine leaks.

Trade-offs​

Pros: Lightweight, easy creation, efficient scheduling
Cons: Requires synchronization, race conditions possible, debugging harder

Goroutines work with context for cancellation and channels for communication.

Quick Reference​

// Start goroutine with go keyword
go doWork()

// Anonymous function goroutine
go func() {
    fmt.Println("Running concurrently")
}()

// With parameters (evaluated immediately)
go process(data)

// Proper cancellation with context
func worker(ctx context.Context) {
    for {
        select {
        case <-ctx.Done():
            return  // Exit when cancelled
        default:
            // do work
        }
    }
}

ctx, cancel := context.WithCancel(context.Background())
go worker(ctx)
// Later: cancel() to stop goroutine

Common Patterns​

Wait for completion:

var wg sync.WaitGroup
wg.Add(1)
go func() {
    defer wg.Done()
    doWork()
}()
wg.Wait()

Fan-out (multiple workers):

for i := 0; i < numWorkers; i++ {
    go worker(i, jobs, results)
}

References​