An extension to PHP called Xdebug is available to assist in profiling PHP applications, as well as runtime debugging. When running the profiler, the output is written to a file in a binary format called "cachegrind". Applications are available on each platform to analyze these files.
To enable profiling, install the extension and adjust php.ini settings. In our example we will run the profile optionally based on a request parameter. This allows us to keep settings static and turn on the profiler only as needed.
// Set to 1 to turn it on for every request xdebug.profiler_enable = 0 // Let's use a GET/POST parameter to turn on the profiler xdebug.profiler_enable_trigger = 1 // The GET/POST value we will pass; empty for any value xdebug.profiler_enable_trigger_value = "" // Output cachegrind files to /tmp so our system cleans them up later xdebug.profiler_output_dir = "/tmp" xdebug.profiler_output_name = "cachegrind.out.%p"
Next use a web client to make a request to your application's URL you wish to profile, e.g.
As the page processes it will write to a file with a name similar to
Note that it will write one file for each PHP request / process that is executed. So, for example, if you wish to analyze a form post, one profile will be written for the GET request to display the HTML form. The XDEBUG_PROFILE parameter will need to be passed into the subsequent POST request to analyze the second request which processes the form. Therefore when profiling it is sometimes easier to run curl to POST a form directly.
Once written the profile cache can be read by an application such as KCachegrind.
This will display information including:
Obviously performance tuning is very specific to each application's use cases. In general it's good to look for:
Note: Xdebug, and in particular its profiling features, are very resource intensive and slow down PHP execution. It is recommended to not run these in a production server environment.