Simple pattern using a channel to throttle the number of concurrent workers

throttle_concurrent_work.go

// change the channel size to the number of concurrent tasks you'd like
var throttle = make(chan struct{}, 1)

func DoStuff() {
	// block until we can add to throttle channel
	throttle <- struct{}{}
	defer func() {
		<-throttle // remove from channel when we are done
	}()
	// do your funky stuff
}