A 30-minute introduction to Go concurrency for developers who know Python but are new to Go. We start with a working Python HTTP service, translate it into Go, and improve it one observable problem at a time. The same URL-checking endpoint introduces goroutines, channels, a bounded worker pool, explicit ownership, cancellation, deadlines, and error handling.
Along the way: concurrency versus parallelism, what the GIL does (and does not) mean, optional free-threaded CPython, goroutines, channels, synchronization, and how to avoid races, leaks, and deadlocks. No promise that Go is always faster—just a practical model for overlapping I/O safely.