摘要：本節講解幾個多進程的實例。新開終端，我們使用命令查看進程可以看到個進程個主進程，個子進程。使用命令結束子進程，主進程會重新拉起一個新的子進程。

本節講解幾個多進程的實例。

下面例子實現了簡單的多進程管理：

支持設置最大子進程數

Master-Worker結構：Worker掛掉，Master進程會重新創建一個

 0){
    exit;//父進程退出
}else{
    // 從當前終端分離
    if (posix_setsid() == -1) {
        die("could not detach from terminal");
    }

    $id = getmypid();   
    echo time()." Master process, pid {$id}
"; 

    for($i=0; $i<$MAX_PROCESS;$i++){
        start_worker_process();
    }

    //Master進程等待子進程退出，必須是死循環
    while(1){
        foreach($pids as $pid){
            if($pid){
                $res = pcntl_waitpid($pid, $status, WNOHANG);
                if ( $res == -1 || $res > 0 ){
                    echo time()." Worker process $pid exit, will start new... 
";
                    start_worker_process();
                    unset($pids[$pid]);
                }
            }
        }
    }
}

/**
 * 創建worker進程
 */
function start_worker_process(){
    global $pids;
    $pid = pcntl_fork();
    if($pid <0){
        exit("fork fail
");
    }elseif($pid > 0){
        $pids[$pid] = $pid;
        // exit; //此處不可退出，否則Master進程就退出了
    }else{
        //實際代碼
        $id = getmypid();   
        $rand = rand(1,3);
        echo time()." Worker process, pid {$id}. run $rand s
"; 
        while(1){
            sleep($rand);
        }
    }
}

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下面我們使用多進程實現一個tcp服務器，支持：

多進程處理客戶端連接

子進程退出，Master進程會重新創建一個

支持事件回調

 0){
            exit;//父進程退出
        } else{
            // 從當前終端分離
            if (posix_setsid() == -1) {
                die("could not detach from terminal");
            }

            umask(0);

            $id = getmypid();   
            echo time()." Master process, pid {$id}
"; 

            //創建tcp server
            $this->socket = stream_socket_server("tcp://0.0.0.0:9201", $errno, $errstr);
            if(!$this->socket) exit("start server err: $errstr --- $errno");
        }
    }

    public function run(){
        for($i=0; $istart_worker_process();
        }

        echo "waiting client...
";

        //Master進程等待子進程退出，必須是死循環
        while(1){
            foreach($this->pids as $k=>$pid){
                if($pid){
                    $res = pcntl_waitpid($pid, $status, WNOHANG);
                    if ( $res == -1 || $res > 0 ){
                        echo time()." Worker process $pid exit, will start new... 
";
                        $this->start_worker_process();
                        unset($this->pids[$k]);
                    }
                }
            }
            sleep(1);//讓出1s時間給CPU
        }
    }

    /**
     * 創建worker進程，接受客戶端連接
     */
    private function start_worker_process(){
        $pid = pcntl_fork();
        if($pid <0){
            exit("fork fail
");
        }elseif($pid > 0){
            $this->pids[] = $pid;
            // exit; //此處不可退出，否則Master進程就退出了
        }else{
            $this->acceptClient();
        }
    }

    private function acceptClient()
    {
        //子進程一直等待客戶端連接，不能退出
        while(1){
            $conn = stream_socket_accept($this->socket, -1);
            if($this->onConnect) call_user_func($this->onConnect, $conn); //回調連接事件

            //開始循環讀取消息
            $recv = ""; //實際收到消息
            $buffer = ""; //緩沖消息
            while(1){
                $buffer = fread($conn, 20);

                //沒有收到正常消息
                if($buffer === false || $buffer === ""){
                    if($this->onClose) call_user_func($this->onClose, $conn); //回調斷開連接事件
                    break;//結束讀取消息，等待下一個客戶端連接
                }

                $pos = strpos($buffer, "
"); //消息結束符
                if($pos === false){
                    $recv .= $buffer;                            
                }else{
                    $recv .= trim(substr($buffer, 0, $pos+1));

                    if($this->onMessage) call_user_func($this->onMessage, $conn, $recv); //回調收到消息事件

                    //客戶端強制關閉連接
                    if($recv == "quit"){
                        echo "client close conn
";
                        fclose($conn);
                        break;
                    }

                    $recv = ""; //清空消息，準備下一次接收
                }
            }
        }
    }

    function __destruct() {
        @fclose($this->socket);
    }
}

$server =  new TcpServer();

$server->onConnect = function($conn){
    echo "onConnect -- accepted " . stream_socket_get_name($conn,true) . "
";
    fwrite($conn,"conn success
");
};

$server->onMessage = function($conn,$msg){
    echo "onMessage --" . $msg . "
";
    fwrite($conn,"received ".$msg."
");
};

$server->onClose = function($conn){
    echo "onClose --" . stream_socket_get_name($conn,true) . "
";
    fwrite($conn,"onClose "."
");
};

$server->run();

運行：

$ php process_multi.server.php 
1528734803 Master process, pid 9110
waiting client...

此時服務端已經變成守護進程了。新開終端，我們使用ps命令查看進程：

$ ps -ef | grep php
yjc       9110     1  0 00:33 ?        00:00:00 php process_multi.server.php
yjc       9111  9110  0 00:33 ?        00:00:00 php process_multi.server.php
yjc       9112  9110  0 00:33 ?        00:00:00 php process_multi.server.php
yjc       9113  9110  0 00:33 ?        00:00:00 php process_multi.server.php
yjc       9134  8589  0 00:35 pts/1    00:00:00 grep php

可以看到4個進程：1個主進程，3個子進程。使用kill命令結束子進程，主進程會重新拉起一個新的子進程。

然后我們使用telnet測試連接：

$ telnet 127.0.0.1 9201
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is "^]".
conn success
hello server!
received hello server!
quit
received quit
Connection closed by foreign host.

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