[文章作者:张宴 本文版本:v1.0 最后修改:2007.06.28 转载请注明出处:http://blog.zyan.cc]

  经济学中有一条著名的80-20定律,引用到编程中,就是:80%的性能瓶颈是由20%的代码引起的。借助PHP的XDebug扩展,可以有效地找出这20%的代码。

  一、安装配置
  1、下载PHP的XDebug扩展,网址:http://xdebug.org/

  2、在Linux下编译安装XDebug
引用
tar -xzf xdebug-2.0.0RC3.gz
cd xdebug-2.0.0RC3
/usr/local/php/bin/phpize
./configure --enable-xdebug
cp modules/xdebug.so /usr/local/php/lib/php/extensions/no-debug-non-zts-20020429/

  注:/usr/local/php/lib/php/extensions/no-debug-non-zts-20020429/不同的PHP版本路径不同,也不一定要放在该路径,可以在zend_extension_ts中自行指定xdebug.so所在位置。

引用
vi /usr/local/php/lib/php.ini

  修改php.ini,去除PHP加速模块,增加以下配置信息支持XDebug扩展

引用
mkdir -p /tmp/xdebug
chmod 755 /tmp/xdebug
chown www:www /tmp/xdebug
/usr/local/apache/bin/apachectl -k restart


  3、客户端(Windows):WinCacheGrind
  下载地址:http://sourceforge.net/projects/wincachegrind/

  二、分析过程
  1、访问你的网站,将首页上各种链接点击几遍,XDebug在/tmp/xdebug目录生成以下文件:
  usr_local_apache_htdocs_app_checknum_chknum_php_cachegrind.out
  usr_local_apache_htdocs_app_login_showHeaderLogin_php_cachegrind.out
  usr_local_apache_htdocs_app_play_play_php_cachegrind.out
  usr_local_apache_htdocs_app_user_member_php_cachegrind.out
  usr_local_apache_htdocs_tag_tags_php_cachegrind.out
  usr_local_apache_htdocs_top_top_php_cachegrind.out

  2、将以上文件拷贝到Windows上,用客户端软件WinCacheGrind打开每个文件,发现以下PHP程序执行所耗费的时间最长:
  /usr/local/apache/htdocs/tag/tags.php      耗时840ms

  三、分析结果:
  1、/usr/local/apache/htdocs/tag/tags.php

  点击在新窗口中浏览此图片

  (1)耗时最长的filter_tags函数出现在/usr/local/apache/htdocs/tag/tags.php的第158行:
  $tags .= filter_tags($videos[$i]['tags'])." ";

  (2)filter_tags函数引自/usr/local/apache/htdocs/include/misc.php,getForbiddenTags函数被filter_tags函数调用了21次,filter_tags函数耗费的时间中绝大多数因getForbiddenTags函数所致。getForbiddenTags函数的内容如下:

  (4)对getForbiddenTags函数进行分析,其中的PHP函数trim被调用了16827次。
  点击在新窗口中浏览此图片

  (5)可能造成瓶颈的原因:
  要过滤的156个关键字逐行存放在/usr/local/apache/template/tags/forbidden_tags.txt文件中,文本数据库的效率不高。
  逐行读取函数fgets、以及去除字符串两边的空白或者指定的字符的函数trim在高负载下的效率低,可以测试fopen、fread、fscanf之类的文件读取函数,对比一下。


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技术大类 » PHP/JS/Shell | 评论(132) | 引用(0) | 阅读(76462)
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