func (p *clientConnPool) getClientConn(req *http.Request, addr string, dialOnMiss bool) (*ClientConn, error) {
	//...
	for {
                 //....

		// if there is no active connection
		traceGetConn(req, addr)
		// for a specific addr, only one call would be created.
		call := p.getStartDialLocked(req.Context(), addr)
		p.mu.Unlock()
		<-call.done

		// If should retry dial for the request, which do not respect to request's context.
		if shouldRetryDial(call, req) {
			continue
		}
		cc, err := call.res, call.err
		if err != nil {
			return nil, err
		}
		if cc.ReserveNewRequest() {
			return cc, nil
		}
	}
}

func shouldRetryDial(call *dialCall, req *http.Request) bool {
	if call.err == nil {
		// No error, no need to retry
		return false
	}
	if call.ctx == req.Context() {
		// If the call has the same context as the request, the dial
		// should not be retried, since any cancellation will have come
		// from this request.
		return false
	}
	if !errors.Is(call.err, context.Canceled) && !errors.Is(call.err, context.DeadlineExceeded) {
		// If the call error is not because of a context cancellation or a deadline expiry,
		// the dial should not be retried.
		return false
	}
	// Only retry if the error is a context cancellation error or deadline expiry
	// and the context associated with the call was canceled or expired.
	return call.ctx.Err() != nil
}