Go: What is context?

Context — cancellation and timeouts.

1ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
2defer cancel()

Usage:

1func handler(w http.ResponseWriter, r *http.Request) {
2    ctx := r.Context()
3    // Use ctx for DB queries, API calls
4}

When to use:

• HTTP requests.
• Database timeouts.

Common mistakes:

• Not calling cancel().
• Storing context in structs.
• Using context.Background() in libraries.
• Using context for non-request data.
• Creating timeout without defer cancel().