Dtrace is really powerful and trying to do an introduction to all it's features is just not possible. Therefore I will just focus on the basics, that are needed to get our stuff working. The basic idea behind Dtrace is that the kernel and userland programs fire probes on a specific location in the kernel or the userland program.

He looks at the structure of a DTrace program as well as a list of probes that you can use to help track down the problem in your application. His "first example" traces the compile time of the app and, when run on the command line, returns the time in seconds.

Yesterday, during a break at the Barcamp Munich, I gave Wolfram a short introduction on his Mac and decided to put some stuff here [in this post]. DTrace is a toolkit available on Solaris (Solaris 10 or OpenSolaris), recent MacOS versions and FreeBSD for mightier than tools like truss or strace but with way less impact. DTrace allows you to "hook" (called "probes") into the system and allows to do some analysis then.

He shows how to set up some of these "hooks" using D-script to wrap around a simple PHP script call. He alters the results to show things like the memory function its in, how much of the memory its using and a fun little script that "graphs" out the memory usage with "@" symbols.