Swoole —— 重新定义PHP
作为一个使用C语言底层实现的PHP扩展，弥补了PHP在多线程、常驻内存相关领域的短处，为广大phper打开了眼界。
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();