One of the three authors of Sun's DTrace, Adam Leventhal, has discovered something very interesting using DTrace on Mac OS X. "As has been thoroughly recorded, Apple has included DTrace in Mac OS X. I've been using it as often as I have the opportunity, and it's a joy to be able to use the fruits of our labor on another operating system. But I hit a rather surprising case recently which led me to discover a serious problem with Apple's implementation." So, what is this problem? "Wow. So Apple is explicitly preventing DTrace from examining or recording data for processes which don't permit tracing. This is antithetical to the notion of systemic tracing, antithetical to the goals of DTrace, and antithetical to the spirit of open source. I'm sure this was inserted under pressure from ISVs, but that makes the pill no easier to swallow. To say that Apple has crippled DTrace on Mac OS X would be a bit alarmist, but they've certainly undermined its efficacy and, in doing do, unintentionally damaged some of its most basic functionality. To users of Mac OS X and of DTrace: Apple has done a service by porting DTrace, but let's convince them to go one step further and port it properly."