这不是ACI的问题，而是如何构建Paho-MQTT客户端的问题。Paho使用select(..)方法，该方法限制我们打开超过1024个文件描述符。
每个MQTT客户端表示3个打开文件描述符：3 * 340 = 1020。超过340个客户端连接，我们达到了1024个打开文件描述符。
我们使用了一个从Paho客户端继承的MQTT用户。我们重写了以下方法来使用eventfd包。

import eventfd

    [...]
    def loop_start(self) -> Optional[int]:
        [...]
        # self._sockpairR, self._sockpairW = _socketpair_compat()
        self._wake_event = EventFD()
        [...]

    def _reset_sockets(self, sockpair_only: bool = False) -> None:
        [...]
        # if self._sockpairR:
        #   self._sockpairR.close()
        #   self._sockpairR = None
        # if self._sockpairW:
        #   self._sockpairW.close()
        #   self._sockpairW = None
        if self._wake_event:
            self._wake_event = None

    def _packet_queue(
        self,
        command: Literal[48],
        packet: bytearray,
        mid: int,
        qos: int,
        info: Optional[Any] = None,
    ) -> int:
        [...]
        # if self._sockpairW is not None:
        #   try:
        #     self._sockpairW.send(sockpair_data)
        #   except BlockingIOError:
        #     pass
        if self._wake_event is not None:
            with suppress(BlockingIOError):
                self._wake_event.set()
        [...]

    def _loop(self, timeout: float = 1.0) -> int:
        [...]
        # if self._sockpairR is None:
        #   rlist = [self._sock]
        # else:
        #   rlist = [self._sock, self._sockpairR]
        if self._wake_event is None:
            rlist = [self._sock]
        else:
            rlist = [self._sock, self._wake_event]
        [...]
        # if self._sockpairR and self._sockpairR in socklist[0]:
        #   socklist[1].insert(0, self._sock)
        #   try:
        #       self._sockpairR.recv(10000)
        #   except BlockingIOError:
        #       pass
        if self._wake_event and self._wake_event.is_set():
            self._wake_event.clear()
        [...]
    [...]