go-concurrencylisted

# Go Concurrency This skill covers concurrency patterns and best practices from Google's Go Style Guide and Uber's Go Style Guide, including goroutine management, channel usage, mutex handling, and synchronization. --- ## Goroutine Lifetimes > **Normative**: When you spawn goroutines, make it clear when or whether they > exit. ### Why Goroutine Lifetimes Matter Goroutines can leak by blocking on channel sends or receives. The garbage collector **will not terminate** a goroutine blocked on a channel even if no other goroutine has a reference to the channel. Even when goroutines do not leak, leaving them in-flight when no longer needed causes: - **Panics**: Sending on a closed channel causes a panic - **Data races**: Modifying still-in-use inputs after the result isn't needed - **Memory issues**: Unpredictable memory usage from long-lived goroutines - **Resource leaks**: Preventing unused objects from being garbage collected ```go // Bad: Sending on closed channel causes panic ch := make(chan int) ch <- 42 close(ch) ch <- 13 // panic ``` ### Make Lifetimes Obvious Write concurrent code so goroutine lifetimes are evident. Keep synchronization-related code constrained within function scope and factor logic into synchronous functions. ```go // Good: Goroutine lifetimes are clear func (w *Worker) Run(ctx context.Context) error { var wg sync.WaitGroup for item := range w.q { wg.Add(1) go func() { defer wg.Done() process(ctx,