gls.go
func Cleanup() {
	gid := curGoroutineID()
	dataLock.Lock()
	delete(data, gid)
	dataLock.Unlock()
}
func Cleanup() {
	gid := curGoroutineID()
	dataLock.Lock()
	delete(data, gid)
	dataLock.Unlock()
}
// Cleanup removes all data associated with this goroutine. If this is not
// called, the data may persist for the lifetime of your application. This
// must be called from the very first goroutine to invoke Set