PHP进程间通信的几种方法详解

PHP是用C编写的，因此它对系统底层API的操作与C很像，同大多数语言一样，PHP进程间通信的方式有以下几种：消息队列，管道，共享内存，socket和信号，本文是对这几种通信方式对整理

管道通信PIPE

管道用于承载简称之间的通讯数据。为了方便理解，可以将管道比作文件，进程A将数据写到管道P中，然后进程B从管道P中读取数据。php提供的管道操作API与操作文件的API基本一样，除了创建管道使用posix_mkfifo函数，读写等操作均与文件操作函数相同。当然，你可以直接使用文件模拟管道，但是那样无法使用管道的特性了。

通过管道通信的大概思路是，首先创建一个管道，然后子进程向管道中写入信息，父进程从管道中读取信息，这样就可以做到父子进程直接实现通信了。

<?php// 创建管道$pipePath = "pipe";if( !file_exists( $pipePath ) ){if( !posix_mkfifo( $pipePath, 0666) ){exit('make pipe false!' . PHP_EOL);}}// 创建进程，子进程写管道，父进程读管道// 通过 pcntl_fork函数创建一个子进程。// pcntl_fork 函数 很特殊，它调用一次拥有 多个返回值。// 在父进程中：它返回 子进程的ID 这个值是 大于0 的。// 在子进程中，它返回0。当返回 -1 时表示创建进程失败。$pid = pcntl_fork();if( $pid == 0 ){// 子进程写管道$file = fopen( $pipePath, 'w');fwrite( $file, 'hello world');sleep(1);exit;}else{// 父进程读管道$file = fopen( $pipePath, 'r');// 设置成读取非阻塞// 当读取是非阻塞的情况下，父进程进行读取信息的时候不会等待，// 管道中没有消息也会立马返回。// stream_set_blocking( $file, False); echo fread( $file, 20) . PHP_EOL;pcntl_wait($status); // 回收子进程}

消息队列

消息队列是存放在内存中的一种队列数据结构。

<?php// 获取父进程id$parentPid = posix_getpid();echo "parent progress pid:{$parentPid}n";$childList = array();// 创建消息队列，定义消息类型$id = ftok(__FILE__, 'm');$msgQueue = msg_get_queue($id);const MSG_TYEP = 1;// 生产者function producer(){global $msgQueue;$pid = posix_getpid();$repeatNum = 5;for ($i = 0; $i <= $repeatNum; $i++) {$str = "({$pid}) progress create! {$i}";msg_send($msgQueue, MSG_TYEP, $str);$rand = rand(1, 3);sleep($rand);}}// 消费者function consumer(){global $msgQueue;$pid = posix_getpid();$repeatNum = 6;for ($i = 1; $i<= $repeatNum; $i++) {$rel = msg_receive($msgQueue, MSG_TYEP, $msgType, 1024, $message);echo "{$message} | consumer({$pid}) destroy n";$rand = rand(1, 3);sleep($rand);}}function createProgress($callback){$pid = pcntl_fork();if ($pid == -1) {// 创建失败exit("fork progresses errorn");} elseif ($pid == 0) {// 子进程执行程序$pid = posix_getpid();$callback();exit("({$pid})child progress end!n");} else {// 父进程return $pid;}}for ($i = 0; $i < 3; $i++) {$pid = createProgress('producer');$childList[$pid] = 1;echo "create producer progresses: {$pid}n";}for ($i = 0; $i < 2; $i++) {$pid = createProgress('consumer');$childList[$pid] = 1;echo "create consumer progresses: {$pid}n";}while (!empty($childList)) {$childPid = pcntl_wait($status);if ($childPid > 0) {unset($childList[$childPid]);}}echo "({$parentPid})main progress end!n";

运行结果：

create producer progresses: 21432create producer progresses: 21433create producer progresses: 21434create consumer progresses: 21435(21426) progress create! 2 | consumer(21435) destroy(21424) progress create! 1 | consumer(21436) destroycreate consumer progresses: 21436(21426) progress create! 3 | consumer(21436) destroy(21426) progress create! 4 | consumer(21435) destroy(21425) progress create! 3 | consumer(21436) destroy(21424) progress create! 2 | consumer(21435) destroy(21426) progress create! 5 | consumer(21435) destroy(21424) progress create! 3 | consumer(21436) destroy(21433)child progress end!(21425) progress create! 4 | consumer(21435) destroy(21424) progress create! 4 | consumer(21436) destroy(21434)child progress end!(21424) progress create! 5 | consumer(21435) destroy(21425) progress create! 5 | consumer(21436) destroy(21432)child progress end!(21435)child progress end!(21436)child progress end!(21431)main progress end!

信号量与共享内存

<?php$parentPid = posix_getpid();echo "parent progress pid:{$parentPid}n";// 创建共享内存,创建信号量，定义共享key// ftok(文件路径，资源标识符) 创建一个IPC通信所需的id$shm_id = ftok(__FILE__, 'm');$shm_id = ftok(__FILE__, 's');// shm_attach(id) 创建或者打开一个共享内存$shareMemory = shm_attach($shm_id);// 返回一个可用户访问系统信号量的id$signal = sem_get($shm_id);const SHARE_KEY = 1;// 生产者function producer() {global $shareMemory;global $signal;$pid = posix_getpid();$repeatNum = 5;for ($i = 1; $i <= $repeatNum; $i++) {// 获得信号量 - 阻塞进程，直到信号量被获取到[lock锁机制的关键]sem_acquire($signal);// 检查某个key是否存在与共享内存中if (shm_has_var($shareMemory, SHARE_KEY)) {// 获取共享内存中的key的值$count = shm_get_var($shareMemory, SHARE_KEY);$count ++;// 为共享内存中的key赋值shm_put_var($shareMemory, SHARE_KEY, $count);echo "({$pid}) count: {$count}n";} else {// 初始化shm_put_var($shareMemory, SHARE_KEY, 0);echo "({$pid}) count: 0n";}// 释放sem_release($signal);}}function createProgress($callback) {$pid = pcntl_fork();if ($pid == -1) {// 创建失败exit("fork progress error!n");} elseif ($pid == 0) {// 子进程$pid = posix_getpid();$callback();exit("({$pid}) child progress end!n");} else {// 父进程return $pid;}}// 3个写进程for ($i = 0; $i < 3; $i ++) {$pid = createProgress('producer');$childList[$pid] = 1;echo "create producer child progress: {$pid} n";}// 等待所有子进程while (!empty($childList)) {$childPid = pcntl_wait($status);if ($childPid > 0) {unset($childList[$childPid]);}}// 释放共享内存与信号量shm_remove($shareMemory);sem_remove($signal);echo "({$parentPid}) main progress end!n";

运行结果：

使用信号量来实现共享内存的锁机制

parent progress pid:31720create producer child progress: 31721create producer child progress: 31722(31721) count: 0(31721) count: 1(31721) count: 2(31721) count: 3(31721) count: 4(31721) child progress end!create producer child progress: 31723(31722) count: 5(31722) count: 6(31722) count: 7(31722) count: 8(31722) count: 9(31722) child progress end!(31723) count: 10(31723) count: 11(31723) count: 12(31723) count: 13(31723) count: 14(31723) child progress end!(31720) main progress end!

无锁情况

Warning: sem_release(): SysV semaphore 4357894312 (key 0x73048925) is not currently acquired in /Users/easyboom/www/example/信号量与共享内存.php on line 38