HOW TO INSTALL XHPROF FOR PROFILING PHP YII 1.X APPLICATION

1. Introduction
   In software engineering, profiling is a technique used to analyze applications at run-time, in order to identify possible bottlenecks and performance issues within an application. It is an essential resource for software optimization. Profiling differs from benchmarking because it analyzes the application at code level, while benchmarking is intended to analyze the overall application performance as experienced by the end user.

   A profiler is a software that will gather detailed information about the application in order to generate statistics and insightful data about memory usage, frequency and duration of function calls, time to respond to a request, amongst other things.XHProf is a profiler designed to analyze PHP applications. Created and open sourced by Facebook, XHProf works as a passive profiler, which means it will work in the background while having minimum impact on the application’s performance, making it suitable to be used on production environments.
   (copy from digital ocean)

2. How to install xhprof
   Update the package manager cache with

   sudo apt-get update

   Next, we’ll install pecl with the php-pear package. We’ll also need php5-dev in order to install PHP modules via pecl
sudo apt-get install php-pear php5-dev
Install xhprof via pecl

   sudo pecl install xhprof-beta

   Edit php.ini file to enable your xhprof extension. Look like the below,
   
   Restart your php daemon, open your phpinfo to make sure xhprof extension is loaded properly,
   

3. How to configure in Yii 1.x application
   Download Yii-xhprof and put into protected/extensions, you will see something like below,
   
   Make sure this config is in your application configuration,

   'preload' => array(
    'xhprof'
    ),

   and

    'components' => array(
       'xhprof' => array(
           'class' => 'ext.yii-xhprof.XHProfComponent',
           'libPath' => '/full/path/to/xhprof_lib',
           'htmlReportBaseUrl' => 'http://url.path.to/xhprof_html',
    ),),

4. How to view the result
   Download PHP view and library package here, extract and copy these into your proper place, mine is in the root of application,
   
   In the xhprof configuration above, configure the libPath point to xhprof_lib folder
   Add virtual host point to xhprof_html in order to view the result. You can use apache or nginx,
   Yah, all will be done, you should see something like this
   
   You can click on Report link to see all the calls
5. How to generate callgraph
   Click on Callgraph for visualization view, you can see all methods’ calls graphically like below
   
   Make sure graphziz is installed on your system, if not you may encounter this problem

   failed to execute cmd: " dot -Tpng". stderr: `sh: 1: dot: not found '

   Install graphziz as the command below

   sudo apt-get install graphviz