Swoole TCP Client Error Broken pipe [32]

Swoole 一个 Server 监听多个端口, 代码如下

// 前端用的
$ws = new \swoole_websocket_server('0.0.0.0', 9502);
$ws->on('message', function ($server, $frame) {
});

// 服务端用
$tcp_server = $ws->addListener('0.0.0.0', 9501, SWOOLE_SOCK_TCP);
$tcp_server->set([]);
$tcp_server->on('receive', function ($server, $fd, $threadId, $data) {
});

TCP Client 发送 json 数据到 TCP Server

$client = new \swoole_client(SWOOLE_SOCK_TCP);

        $address = '127.0.0.1';
        $port = '9501';

        if ($client->connect($address, $port, -1)) {
            try {
                $result = $client->send(json_encode(['code' => 'order_receive', 'data' => 39]));
                $this->info($result);
                $client->close();
            } catch (\Exception $exception) {
                $this->error($exception->getMessage());
            }
        }

发生错误:

Swoole\Client::send(): failed to send(5) 34 bytes, Error: Broken pipe[32]

最近才接触 Swoole, 不是很懂, 请大神指点