[文章作者:张宴 本文版本:v1.0 最后修改:2007.11.16 转载请注明出处:http://blog.zyan.cc]

  最近遇到一个问题,Linux下的PHP命令行程序作为守护进程,需要从队列文件中读一行数据,通过TCP协议发送给外地的接收服务器,再读下一行数据,再发送。当本地与外地的网络状况不好时,有时候发送一条数据所耗费的时间就较长,累积起来容易造成队列堵塞和延迟。

  于是,我准备用该PHP命令行程序生成多个子进程,将串行处理变成并行处理。最简单的方法就是在PHP中用exec()或popen()函数将一个shell命令行推到后台去执行,例如:
<?php
exec("/bin/sh /opt/zhangyan.sh &");
?>
  最后的&表示将shell脚本推到后台去执行。

  但是这样会有一个问题,如果推到后台的进程太多,可能会导致服务器系统资源耗尽而崩溃,所以必须控制进程数量。



  我写了一个PHP程序(/opt/zhangyan.php)、一个shell程序(/opt/zhangyan.sh)作为测试用例。

  程序的逻辑:
  1、设置/opt/zhangyan.php最多允许生成500个子进程;
  2、当/opt/zhangyan.php读取到一条数据后,将允许生成的子进程数减1(空闲进程数$p_number=500-1=499),然后将数据交给/opt/zhangyan.sh去后台处理,不等待/opt/zhangyan.sh处理结束,继续读取下一条数据;
  3、当允许生成的子进程数减至0时(空闲进程数$p_number=0),/opt/zhangyan.php会等待1秒钟,然后检查后台还有多少个/opt/zhangyan.sh子进程尚未处理结束;
  4、如果1秒钟之后/opt/zhangyan.php发现后台的/opt/zhangyan.sh子进程数还是500(空闲进程数$p_number=0),会继续等待1秒钟,如此反复;
  5、如果/opt/zhangyan.php发现后台尚未处理结束的/opt/zhangyan.sh子进程数减少到300个了(空闲进程数$p_number=500-300=200),那么/opt/zhangyan.php会再往后台推送200个/opt/zhangyan.sh子进程;



/opt/zhangyan.php代码如下:  (/opt/zhangyan.php程序用来模拟从队列文件中读取1000行数据,交给子进程/opt/zhangyan.sh去处理。)



/opt/zhangyan.sh代码如下:  (/opt/zhangyan.sh脚本用来模拟向外地接收服务器发送数据。其中的$(expr $RANDOM % 4 + 1)用来生成1~5之间的随机数,用来使程序暂停1~5秒钟。暂停1秒表示网络状况好,发送数据顺畅;暂停2~6秒表示网络状况不好,发送过程需要1~5秒。)



 执行程序:
/usr/local/php/bin/php /opt/zhangyan.php

 (/usr/local/php/bin/php因PHP解析器所在的路径)

 查看/opt/zhangyan.sh打下的日志文件的第一行和最后一行:
head -n 1 /opt/zhangyan.log
 2007-11-16 07:54:13 http://blog.zyan.cc
tail -n 1 /opt/zhangyan.log
 2007-11-16 07:54:18 http://blog.zyan.cc

  可以看出,500进程并发处理这1000条数据只耗费5秒钟。而按照原来的串行模式,处理每条数据即使只耗费最短的1秒钟,也需要1000秒,约合16分钟才能完成。



 PS:将PHP程序作为Linux守护进程的方法:
nohup /usr/local/php/bin/php /opt/zhangyan.php 2>&1 > /dev/null &

 (nohup命令可以在用户退出终端后仍然执行程序,“2>&1 > /dev/null”表示不显示标准输出和错误输出,最后的&表示推到后台执行。)


Tags: ,
技术大类 » PHP/JS/Shell | 评论(34) | 引用(4) | 阅读(60328)
劲草 Email
2007-11-16 14:53
很好,很强大,grin
很喜欢你的程序。。。尤其是APMServ。
不过遗憾的是你的APMServ到2.0版就没动静了呀。
现在PHP5出了5.2.5了,修改了很多Bug。。
MySQL也出了5.0的新版了,应该会有改进吧。。
Apache貌似也更新了一些东东。。。
不知道你是否会把APMServ继续更新下去,期待你的新作。。。
张宴 回复于 2007-11-16 17:53
近期太忙了,APMServ还得等等才能出新版。
pdo
2007-11-16 16:46
博主你使用什么数据库啊?
想用您哪个编译的方法安装带PDO和PDO_ibm的nginx服务器,不知道如何下手。

可否抽空实验一下啊?

感谢
张宴 回复于 2007-11-16 17:53
用的是MySQL
APM用户
2007-11-17 10:52
建议你先出个过渡版本的APMServ,把Apache、PHP5、MySQL,phpMyAdmin等模块更新至最新版本,至于APMServ.exe这个程序如果没时间的话,那些尚未完成的功能在以后再添加。
毕竟新版的Apache、PHP5、MySQL修补了很多的漏洞和Bug。
个人愚见,希望你考虑一下。。
水草萍 Homepage
2008-1-25 13:00
博主尝试过stream_select()吗?据说可以实现进程的并发。
projector
2008-5-27 01:33
进程内实现事件驱动模型可以很好的解决这个问题。
fastcgi的工作机制就是那样。

当然现在的解决方法非常的简洁,不过也容易出现问题,呵呵。
niniwzw
2009-11-17 16:15
我觉得用 纯PHP的解决方案 pcntl 控制线程更加的完美。
最好,不要每次启动一个进程,然后关闭一个进程。让500个进程常驻内存进行发送,
但是,这样的话,可能控制并发比较麻烦点。
Mr.cuix Email
2010-10-21 11:37
张大哥 我做了一个php来执行 .sh脚本,但是通过php来执行.sh脚本会产生一个假死进程,而在服务器上执行该.sh脚本是没问题的php 是用nobody权限nobody 已经在 /etc/sudoers 中添加了.sh脚本中所要执行的程序目录。不知是怎么回事了
yong
2010-12-7 11:07
你好,请教一下:可以用php 来执行 php 脚本吗?也就是把你的zhangyan.sh  用一个php 的脚本zhangyan.php代替?
hh Homepage
2011-1-17 18:36
可以,使用exec
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