Goroutines and channels — the Go concurrency model explained_

A channel is a typed, goroutine-safe queue. Send with ch <- value, receive with value := <-ch. Channels can be buffered (non-blocking up to capacity) or unbuffered (sender blocks until receiver is ready). They are the idiomatic way to share data between goroutines.

The context package is how you propagate cancellation and deadlines through a goroutine tree. Every long-running function should accept a context.Context as its first parameter. When the context is cancelled, the function should stop and return. This is idiomatic Go.

The Go mantra: do not communicate by sharing memory; share memory by communicating. Instead of a shared variable protected by a mutex, pass ownership of data through a channel. This eliminates whole classes of race conditions. The mutex is still there when you need it, but channels are the default.

A goroutine is like a thread but much cheaper — the initial stack is a few kilobytes and grows as needed. You can launch thousands of goroutines without worrying about memory. The Go runtime multiplexes them onto OS threads automatically.