Sometimes when you have a long running PHP script, you might wonder what the hell it is doing at the moment. There are a few tools that can help you to find out, without having to stop the script. Some of these work only on Linux.

He shows you how to use the following commands to track down exactly what your process is working on: strace, ltrace and gdb (a handy debugger that will probably give you more information than you're looking for). He includes some sample output for the commands and gives an example of a PHP script-to-gdb output relationship.

However, because we as PHP developers are lazy, provide a few GDB tricks to make this easier. First of all, it's only really going to work if you haven't stripped the symbols from your PHP and Apache binaries. Secondly, you still need to have the PHP source lying around somewhere.

He suggests using GDB to run the backtraces and create a file to help you track down the infinite recursion problem that could be giving you issues.