<?php
class Server
{
    private $mpid; //主进程id
    private $pids = []; //子进程数组
    private $socket; //网络套间字
    const Max_PROCESS = 3; //最大创建进程数
    //主进程逻辑
    public function run()
    {
        $process = new \Swoole\Process(function () {
            //获取主进程id
            $this->mpid = posix_getpid();
            echo time() . " master process pid: {$this->mpid}" . PHP_EOL;
            //创建TCP服务器并获取套间字
            $this->socket = stream_socket_server("tcp://127.0.0.1:9505", $errno, $errstr);
            if (!$this->socket) {
                exit("service start error:$errstr --- $errno");
            }
            //启动子进程
            for ($i = 1; $i <= self::Max_PROCESS; $i++) {
                $this->startWorkerProcess();
            }
            echo "Waiting client connect" . PHP_EOL;
            //主进程等待子进程退出 必须是死循环
            while (1) {
                if(count($this->pids)){
                    //回收结束运行的子进程,默认为阻塞,false 表示非阻塞模式,如果失败返回 false
                    $ret = \Swoole\Process::wait(false);
                    if ($ret) {
                        echo time() . " worker process: {$ret['pid']} exit ,then new process..." . PHP_EOL;
                        //新创建一个子进程
                        $this->startWorkerProcess();
                        //从数组中删除这个已不存在的子进程 pid
                        $index=array_search($ret['pid'],$this->pids);
                        unset($this->pids[$index]);
                    }
                }
                sleep(1);  //
            }
        }, false, false);
        //把当前进程升级为守护进程
        \Swoole\Process::daemon();
        $process->start();
    }
    //创建子进程
    public function startWorkerProcess()
    {
        $process = new \Swoole\Process(function (\Swoole\Process $work) {
            $this->acceptClient($work);
        }, false, false);
        $pid = $process->start();
        $this->pids[] = $pid;
    }
    //接收客户端请求
    public function acceptClient(&$worker)
    {
        //子进程等待客户端连接,不能退出
        while (1) {
            //接收由 stream_socket_server()创建的的套间字连接
            $conn = stream_socket_accept($this->socket, -1);
            //如果定义了连接回调的地址,就调用
            if ($this->onConnect) {
                call_user_func($this->onConnect, $conn);
            }
            //开始循环读取客户端信息
            $recv = ''; //实际接收数据
            $buffer = ''; //缓冲数据
            while (1) {
                //检查主进程是否正常,如果不正常,退出子进程
                $this->checkmPid($worker);
                //读取客户端信息
                $buffer = fread($conn, 20);
                //如果没有消息
                if ($buffer === false || $buffer === '') {
                    //如果设置了了解关闭的回调函数,那么执行关闭回调
                    if ($this->onClose) {
                        call_user_func($this->onClose, $conn);
                    }
                    //等待下一个连接消息
                    break;
                }
                //消息结束的位置
                $pos = strpos($buffer, "\n");
                //没有结束符,说明还没有读完
                if (false === $pos) {
                    $recv .= $buffer; //拼接消息
                } else {              //消息读完了,处理消息
                    $recv .= trim(substr($buffer, 0, $pos + 1));
                    //如果定义了处理消息回调的函数,那就直接调用回调
                    if ($this->onMessage) {
                        call_user_func($this->onMessage, $conn, $recv);
                    }
                    //如果接收到quit 表示退出,那么关闭这个链接,等待下一个客户端连接
                    if ($recv === 'quit') {
                        echo 'client close' . PHP_EOL;
                        fclose($conn);
                        break;
                    }
                }
                //清空消息
                $recv = '';
            }
        }
    }
    public function checkmPid(&$worker)
    {
        //说明主进程不存在,子进程此时是僵尸进程,需要退出
        if (!\Swoole\Process::kill($this->mpid, 0)) {
            $worker->exit();
            echo "worker: {$worker->pid} exit" . PHP_EOL;
        }
    }
}
$server = new Server();
//连接回调
$server->onConnect = function ($conn) {
    echo "onConnect -- accepted " . stream_socket_get_name($conn, true) . PHP_EOL;
};
//接收消息回调
$server->onMessage = function ($conn, $msg) {
    echo "message is ------ $msg" . PHP_EOL;
    fwrite($conn, "received: " . $msg . "\n");
};
//关闭回调
$server->onClose = function ($conn) {
    echo "close---" . stream_socket_get_name($conn, true) . PHP_EOL;
};
$server->run();

Client
<?php
go(function () {
    $client = new \Swoole\Coroutine\Client(SWOOLE_SOCK_TCP);
    // 尝试与指定 TCP 服务端建立连接（IP和端口号需要与服务端保持一致，超时时间为0.5秒）
    if ($client->connect("127.0.0.1", 9505, 0.5)) {
        // 建立连接后发送内容
        $client->send("hello world\n");
        // 打印接收到的消息
        echo $client->recv().PHP_EOL;
        sleep(2);
        // 关闭连接
        $client->close();
    } else {
        echo "connect failed.";
    }
});