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 "{$pid} destroyed\n"; break; } } } echo "任务{$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 $master_pid start\n"; while ($ret = swoole_process::wait()) { $pid = $ret['pid']; echo "process {$pid} existed\n"; } } /** * 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();