Is connet_timeout not used in the AsyncHTTPClient stream connect timeout？

In the AsyncHTTPClient source code.

    def _on_timeout(self, info: str = None) -> None:
        self._timeout = None
        error_message = "Timeout {0}".format(info) if info else "Timeout"
        if self.final_callback is not None:
            self._handle_exception(
                HTTPTimeoutError, HTTPTimeoutError(error_message), None
            )

    def _handle_exception(
        self,
        typ: "Optional[Type[BaseException]]",
        value: Optional[BaseException],
        tb: Optional[TracebackType],
    ) -> bool:
        if self.final_callback:
            self._remove_timeout()
            if isinstance(value, StreamClosedError):
                if value.real_error is None:
                    value = HTTPStreamClosedError("Stream closed")
                else:
                    value = value.real_error
            self._run_callback(
                HTTPResponse(
                    self.request,
                    599,
                    error=value,
                    request_time=self.io_loop.time() - self.start_time,
                    start_time=self.start_wall_time,
                )
            )

            if hasattr(self, "stream"):
                # TODO: this may cause a StreamClosedError to be raised
                # by the connection's Future.  Should we cancel the
                # connection more gracefully?
                self.stream.close()

        timeout = min(self.request.connect_timeout, self.request.request_timeout)
            if timeout:
                self._timeout = self.io_loop.add_timeout(
                    self.start_time + timeout,
                    functools.partial(self._on_timeout, "while connecting"),
                )
                stream = await self.tcp_client.connect(
                    host,
                    port,
                    af=af,
                    ssl_options=ssl_options,
                    max_buffer_size=self.max_buffer_size,
                    source_ip=source_ip,
                )

    async def connect(
        self,
        host: str,
        port: int,
        af: socket.AddressFamily = socket.AF_UNSPEC,
        ssl_options: Union[Dict[str, Any], ssl.SSLContext] = None,
        max_buffer_size: int = None,
        source_ip: str = None,
        source_port: int = None,
        timeout: Union[float, datetime.timedelta] = None,
    ) -> IOStream:
        if timeout is not None:
            if isinstance(timeout, numbers.Real):
                timeout = IOLoop.current().time() + timeout
            elif isinstance(timeout, datetime.timedelta):
                timeout = IOLoop.current().time() + timeout.total_seconds()
            else:
                raise TypeError("Unsupported timeout %r" % timeout)
        if timeout is not None:
            addrinfo = await gen.with_timeout(
                timeout, self.resolver.resolve(host, port, af)
            )
        else:
            addrinfo = await self.resolver.resolve(host, port, af)
        connector = _Connector(
            addrinfo,
            functools.partial(
                self._create_stream,
                max_buffer_size,
                source_ip=source_ip,
                source_port=source_port,
            ),
        )
        af, addr, stream = await connector.start(connect_timeout=timeout)
........

    def start(
        self,
        timeout: float = _INITIAL_CONNECT_TIMEOUT,
        connect_timeout: Union[float, datetime.timedelta] = None,
    ) -> "Future[Tuple[socket.AddressFamily, Any, IOStream]]":
        self.try_connect(iter(self.primary_addrs))
        self.set_timeout(timeout)
        if connect_timeout is not None:
            self.set_connect_timeout(connect_timeout)
        return self.future

When connect timeout , though, _on_timeout let we can get a return.
But self.tcp_client.connect, timeout and connect_timeout is None. If the client connet to server timeout, though we can get a return in our application, it seems like the socket is going to stay blocked and not be closed here.Because at this point, there is no stream in the self. How do I set a value for connect_timeout if i needn't change the source code

Start with the AsyncHTTPClient connection path, then inspect TCPClient.connect and _Connector.start, especially how connect_timeout is passed and how the socket is closed after a timeout. Reproduce a server connection timeout and verify that the application receives the timeout response and that no connection remains blocked or open.