Go Concurrency & Primitives Cheat Sheet

1. Channel Rules of Thumb

• The Sender Closes the Channel: Never close a channel from the receiver side.
• Never Close a Nil Channel: Panics at runtime.
• Reading from a Closed Channel: Returns the zero value and ok = false.
• Writing to a Closed Channel: Panics at runtime.

2. Worker Pool Pattern with Context

func Worker(ctx context.Context, jobs <-chan int, results chan<- int) {
    for {
        select {
        case <-ctx.Done():
            return
        case j, ok := <-jobs:
            if !ok {
                return
            }
            results <- j * 2
        }
    }
}

3. Atomic Operations

For simple counters, prefer sync/atomic over mutex locks:

import "sync/atomic"

var requestCount atomic.Uint64
requestCount.Add(1)