This session teaches you how to detect and debug PHP scripts with the free open source tool Xdebug, which is an extension to PHP. The first part will quickly show how to get started with Xdebug. The second part of the session will cover detecting problems in your scripts by showing how Xdebug provides debugging aides in the form of stack/function traces, dumps of variables, modified PHP functions. In the last part I will show the remote debugger capabilities of Xdebug, where you can: set breakpoints on functions, methods and file/line combinations; watch execution details such as stack frames, per-frame information; run PHP code to modify the current state of your script and evaluating error messages. On top of this you will also see how you can use Xdebug’s profiler to find bottlenecks in your applications.

https://www.youtube.com/watch?v=tXRxbTAeccg