lbclient.go
func (cc *LBClient) DoTimeout(req *Request, resp *Response, timeout time.Duration) error {
	deadline := time.Now().Add(timeout)
	return cc.get().DoDeadline(req, resp, deadline)
}
func (cc *LBClient) DoTimeout(req *Request, resp *Response, timeout time.Duration) error {
	deadline := time.Now().Add(timeout)
	return cc.get().DoDeadline(req, resp, deadline)
}
// DoTimeout calculates deadline and calls DoDeadline on the least loaded client