swoole_process实现进程池的方法示例

swoole —— 重新定义PHP

swoole 的进程之间有两种通信方式，一种是消息队列(queue)，另一种是管道(pipe)，对swoole_process 的研究在swoole中显得尤为重要。

预备知识

IO多路复用

swoole 中的io多路复用表现为底层的 epoll进程模型，在C语言中表现为 epoll 函数。

• epoll 模型下会持续监听自己名下的素有socket 描述符 fd
• 当触发了 socket 监听的事件时，epoll 函数才会响应，并返回所有监听该时间的 socket 集合
• epoll 的本质是阻塞IO，它的优点在于能同事处理大量socket连接

Event loop 事件循环

swoole 对 epoll 实现了一个Reactor线程模型封装，设置了read事件和write事件的监听回调函数。（详见swoole_event_add）

• Event loop 是一个Reactor线程，其中运行了一个epoll实例。
• 通过swoole_event_add将socket描述符的一个事件添加到epoll监听中，事件发生时将执行回调函数
• 不可用于fpm环境下，因为fpm在任务结束时可能会关掉进程。

swoole_process

• 基于C语言封装的进程管理模块，方便php来调用
• 内置管道、消息队列接口，方便实现进程间通信

我们在php-fpm.conf配置文件中发现，php-fpm中有两种进程池管理设置。

• 静态模式 即初始化固定的进程数，当来了一个请求时，从中选取一个进程来处理。
• 动态模式 指定最小、最大进程数，当请求量过大，进程数不超过最大限制时，新增线程去处理请求

接下来用swoole代码来实现，这里只是为理解swoole_process、进程间通信、定时器等使用，实际情况使用封装好的swoole_server来实现task任务队列池会更方便。

假如有个定时投递的任务队列：

  <?php    /**   * 动态进程池，类似fpm   * 动态新建进程   * 有初始进程数，最小进程数，进程不够处理时候新建进程，不超过最大进程数   */    // 一个进程定时投递任务    /**   * 1. tick   * 2. process及其管道通讯   * 3. event loop 事件循环   */  class processPool  {    private $pool;      /**     * @var swoole_process[] 记录所有worker的process对象     */    private $workers = [];      /**     * @var array 记录worker工作状态     */    private $used_workers = [];      /**     * @var int 最小进程数     */    private $min_woker_num = 5;      /**     * @var int 初始进程数     */    private $start_worker_num = 10;      /**     * @var int 最大进程数     */    private $max_woker_num = 20;      /**     * 进程闲置销毁秒数     * @var int     */    private $idle_seconds = 5;      /**     * @var int 当前进程数     */    private $curr_num;      /**     * 闲置进程时间戳     * @var array     */    private $active_time = [];      public function __construct()    {      $this->pool = new swoole_process(function () {        // 循环建立worker进程        for ($i = 0; $i < $this->start_worker_num; $i++) {          $this->createWorker();        }        echo '初始化进程数：' . $this->curr_num . PHP_EOL;        // 每秒定时往闲置的worker的管道中投递任务        swoole_timer_tick(1000, function ($timer_id) {          static $count = 0;          $count++;          $need_create = true;          foreach ($this->used_workers as $pid => $used) {            if ($used == 0) {              $need_create = false;              $this->workers[$pid]->write($count . ' job');              // 标记使用中              $this->used_workers[$pid] = 1;              $this->active_time[$pid] = time();              break;            }          }          foreach ($this->used_workers as $pid => $used)            // 如果所有worker队列都没有闲置的，则新建一个worker来处理            if ($need_create && $this->curr_num < $this->max_woker_num) {              $new_pid = $this->createWorker();              $this->workers[$new_pid]->write($count . ' job');              $this->used_workers[$new_pid] = 1;              $this->active_time[$new_pid] = time();            }            // 闲置超过一段时间则销毁进程          foreach ($this->active_time as $pid => $timestamp) {            if ((time() - $timestamp) > $this->idle_seconds && $this->curr_num > $this->min_woker_num) {              // 销毁该进程              if (isset($this->workers[$pid]) && $this->workers[$pid] instanceof swoole_process) {                $this->workers[$pid]->write('exit');                unset($this->workers[$pid]);                $this->curr_num = count($this->workers);                unset($this->used_workers[$pid]);                unset($this->active_time[$pid]);                echo "{$pid} destroyedn";                break;              }            }          }            echo "任务{$count}/{$this->curr_num}n";            if ($count == 20) {            foreach ($this->workers as $pid => $worker) {              $worker->write('exit');            }            // 关闭定时器            swoole_timer_clear($timer_id);            // 退出进程池            $this->pool->exit(0);            exit();          }        });        });        $master_pid = $this->pool->start();      echo "Master $master_pid startn";        while ($ret = swoole_process::wait()) {        $pid = $ret['pid'];        echo "process {$pid} existedn";      }    }      /**     * 创建一个新进程     * @return int 新进程的pid     */    public function createWorker()    {      $worker_process = new swoole_process(function (swoole_process $worker) {        // 给子进程管道绑定事件        swoole_event_add($worker->pipe, function ($pipe) use ($worker) {          $data = trim($worker->read());          if ($data == 'exit') {            $worker->exit(0);            exit();          }          echo "{$worker->pid} 正在处理 {$data}n";          sleep(5);          // 返回结果，表示空闲          $worker->write("complete");        });      });        $worker_pid = $worker_process->start();        // 给父进程管道绑定事件      swoole_event_add($worker_process->pipe, function ($pipe) use ($worker_process) {        $data = trim($worker_process->read());        if ($data == 'complete') {          // 标记为空闲  //        echo "{$worker_process->pid} 空闲了n";          $this->used_workers[$worker_process->pid] = 0;        }      });        // 保存process对象      $this->workers[$worker_pid] = $worker_process;      // 标记为空闲      $this->used_workers[$worker_pid] = 0;      $this->active_time[$worker_pid] = time();      $this->curr_num = count($this->workers);      return $worker_pid;    }    }    new processPool();