How to Check If a Channel Is Closed in Go

Use a select statement with a default case to check if a channel is closed without blocking. If the channel is closed, the receive operation returns the zero value immediately; if open, the default case executes.

func isClosed(ch <-chan struct{}) bool {
	select {
	case <-ch:
		return true
	default:
		return false
	}
}

Note: This only works reliably if you are sure no other goroutine is sending to the channel at that exact moment, or if the channel is unbuffered and you control the sends.

A closed channel is like a pipe that has been permanently shut off; you can't put anything new in it, and trying to read from it just gives you an empty signal. This check lets your program peek at the pipe to see if it's shut off without waiting around for something that might never come. It's essential for stopping loops cleanly when a background task finishes.