端代码，已经测试完毕。

服务器环境  centos7.0  swoole4.3 php7.2 pcre4.8  nginx1.8   php-fpm

server.php

<?php 

class Server
{
    private $serv;

    public function __construct() {

        $this->serv = new swoole_server("0.0.0.0", 9501);

        $this->serv->set(array(
            'worker_num' => 8,
            'daemonize' => false,
            'max_request' => 10000,
            'dispatch_mode' => 2,
            'debug_mode'=> 1
        ));

        $this->serv->on('Start', array($this, 'onStart'));
        $this->serv->on('Connect', array($this, 'onConnect'));
        //$this->serv->on('Message', array($this, 'onMessage'));
        $this->serv->on('Receive', array($this, 'onReceive'));
        $this->serv->on('Close', array($this, 'onClose'));

        $this->serv->start();
    }

    public function onStart( $serv ) {
        echo "Start\n";
    }

    public function onConnect( $serv, $fd, $from_id ) {
        $serv->send( $fd, "收到 {$fd}!" );
    }

    // public function onMessage( $serv, $fd, $from_id ) {
    //     $serv->send( $fd, "Hello {$fd}!我已经收到你的信息" );
    // }

    public function onReceive( $serv, $fd, $from_id, $data ) {
        echo "Get Message From Client {$fd}:{$data}\n";

        $serv->send( $fd, "Hello {$fd}!我收到了你的信息!{$data}" );

    }

    public function onClose( $serv, $fd, $from_id ) {
        echo "Client {$fd} close connection\n";
    }
}
// 启动服务器
$server = new Server();

?>

client.php 异步非阻塞

<?php

$client = new swoole_client(SWOOLE_TCP | SWOOLE_ASYNC); //异步非阻塞

$client->on("connect", function($cli) {
    $cli->send("hello world\n");
});

$client->on("receive", function($cli, $data) {

    echo "received: $data\n";
    //sleep(1);
    fwrite(STDOUT, "请输入消息：");  
            
    $msg = trim(fgets(STDIN));

    $cli->send( $msg );
});

$client->on("close", function($cli){
    echo "closed\n";
});

$client->on("error", function($cli){
    exit("error\n");
});

$client->connect('0.0.0.0', 9501, 0.5);



?>

测试结果