Process

swoole-1.7.2增加了一个进程管理模块，用来替代PHP的pcntl扩展。

需要注意Process进程在系统是非常昂贵的资源，创建进程消耗很大。另外创建的进程过多会导致进程切换开销大幅上升。可以使用vmstat指令查看操作系统每秒进程切换的次数。

vmstat 1 1000
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 8250028 509872 4061168    0    0    10    13   88   86  1  0 99  0  0
 0  0      0 8249532 509872 4061936    0    0     0     0  451 1108  0  0 100  0  0
 0  0      0 8249532 509872 4061884    0    0     0     0  684 1855  1  3 95  0  0
 0  0      0 8249532 509880 4061876    0    0     0    16  492 1332  0  0 99  0  0
 0  0      0 8249532 509880 4061844    0    0     0     0  379  893  0  0 100  0  0
 0  0      0 8249532 509880 4061844    0    0     0     0  440 1116  0  0 99  0  0

PHP自带的pcntl，存在很多不足，如

swoole_process提供了如下特性：

一个同步实例:

(new class{
    public $mpid=0;
    public $works=[];
    public $max_precess=1;
    public $new_index=0;

    public function __construct(){
        try {
            swoole_set_process_name(sprintf('php-ps:%s', 'master'));
            $this->mpid = posix_getpid();
            $this->run();
            $this->processWait();
        }catch (\Exception $e){
            die('ALL ERROR: '.$e->getMessage());
        }
    }

    public function run(){
        for ($i=0; $i < $this->max_precess; $i++) {
            $this->CreateProcess();
        }
    }

    public function CreateProcess($index=null){
        $process = new swoole_process(function(swoole_process $worker)use($index){
            if(is_null($index)){
                $index=$this->new_index;
                $this->new_index++;
            }
            swoole_set_process_name(sprintf('php-ps:%s',$index));
            for ($j = 0; $j < 16000; $j++) {
                $this->checkMpid($worker);
                echo "msg: {$j}\n";
                sleep(1);
            }
        }, false, false);
        $pid=$process->start();
        $this->works[$index]=$pid;
        return $pid;
    }
    public function checkMpid(&$worker){
        if(!swoole_process::kill($this->mpid,0)){
            $worker->exit();
            // 这句提示,实际是看不到的.需要写到日志中
            echo "Master process exited, I [{$worker['pid']}] also quit\n";
        }
    }

    public function rebootProcess($ret){
        $pid=$ret['pid'];
        $index=array_search($pid, $this->works);
        if($index!==false){
            $index=intval($index);
            $new_pid=$this->CreateProcess($index);
            echo "rebootProcess: {$index}={$new_pid} Done\n";
            return;
        }
        throw new \Exception('rebootProcess Error: no pid');
    }

    public function processWait(){
        while(1) {
            if(count($this->works)){
                $ret = swoole_process::wait();
                if ($ret) {
                    $this->rebootProcess($ret);
                }
            }else{
                break;
            }
        }
    }
});