php父子进程通信
多进程demo里介绍过,如何fork子进程。 但是,谁家的孩子谁管,你fork了得记得处理啊,不然哪天捣点乱啥的,是吧。 进程与进程之间通信的方式有很多种,这里用最简单的信号通信。当我们kill -9 一个进程的时候,实际上就是向该进程发送一个终止信号,之前已
多进程demo里介绍过,如何fork子进程。
但是,谁家的孩子谁管,你fork了得记得处理啊,不然哪天捣点乱啥的,是吧。
进程与进程之间通信的方式有很多种,这里用最简单的信号通信。当我们kill -9 一个进程的时候,实际上就是向该进程发送一个终止信号,之前已经绑定了信号处理器,所以,我们可以用其他进程通知另一个进程做出相应的反应(kill -9 的时候是退出)。父子进程通信也不例外,父进程绑定信号处理器,用来协调子进程,子进程向父进程发送信号,让父进程有相应的反应。
绑定信号处理器:pcntl_signal http://cn2.php.net/manual/en/function.pcntl-signal.php#70161
发送信号:posix_kill http://cn2.php.net/manual/en/function.posix-kill.php
需要注意一点,信号的不可重入性,当一个子进程的信号处理器正处理时,将忽略其他的信号处理。所以,需要pcntl_watipid
http://cn2.php.net/manual/en/function.pcntl-waitpid.php 来等待。
运用上边的理论,实现了一个固定子进程处理任务的程序:
父进程fork子进程,然后绑定SIGCHLD信号,子进程结束触发父进程的SIGCHLD信号处理器,末尾主循环,统计子进程的个数,当低于指定值时,fork新的子进程:代码如下:
<?php declare(ticks=1); $child_nums = 0; function catch_signal($signal){ global $child_nums; while( pcntl_waitpid(-1, $status, WNOHANG) > 0 ) { if($signal == SIGCHLD){ $child_nums--; } } } function fork_do($c){ global $child_nums; while($c--) { if(pcntl_fork() == 0 ) { real_do(); } else { $child_nums++; } } } function real_do(){ sleep(rand(1,3)); exit(); } $manage_pid = getmypid(); $fork_nums = 4; pcntl_signal(SIGCHLD,'catch_signal'); fork_do($fork_nums); while($child_nums != 0){ echo "Childs " . $child_nums . "\n"; if($child_nums <p>注:要看动态效果显得很酷的话,把sleep改成usleep或者干脆去掉吧。</p> <p class="copyright"> 原文地址:php父子进程通信, 感谢原作者分享。 </p>

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