The keynote of the much anticipated Apple WWDC 2006 is over and besides revealing the features of the upcoming Mac OS X Leopard, Apple has announced Xcode 3.0. This is the primary IDE and developer toolset for Mac OS X. The feature preview of Xcode 3.0 gives some information about a new tool named Xray. It visualizes metrics gathered from the instrumentation of applications, and possibly of the OS itself — I quote: "such Xray instruments leverage the open source DTrace, now built into Mac OS X Leopard". It seems Apple has ported the DTrace framework from Sun’s OpenSolaris or from FreeBSD to Mac OS X! Wow, this is really great news. I use DTrace regularly for tracking performance problems under Solaris and it’s a fantastic system.
DTrace enables performance tuning with applications and troubleshoot production systems — all with little or no performance impact. DTrace also provides improved visibility into kernel and application activity, giving the user operational insights with which they can make performance gains. Here are some examples to illustrate the power of DTrace for application and system diagnosis: Using DTrace to Profile and Debug A C++ Program, DTrace How To Guides, DTrace Tools and Top Ten DTrace Scripts. Did I mention the J2SE 6.0 built-in Dtrace Support? And for the seriously interested, the original Usenix paper about DTrace, "Dynamic Instrumentation of Production Systems" (2004), and the ACM Queue article "Hidden in Plain Sight" (2006) give valueable details on its motivation and concepts.
Update: $<blog in its entry DTrace on MacOS X at WWDC gives some more details on the DTrace integration into Mac OS X Leopard.