DTrace

DTrace is a dynamic tracing framework for Mac OS X, originally developed by Sun Microsystems, that allows users to analyze the behavior of applications and the operating system without the need for restarting or recompiling. It provides extensive instrumentation capabilities and scripting through the D language, with over 20,000 probes available after startup for detailed monitoring. As open-source software, DTrace is beneficial for administrators, developers, and service personnel seeking insights into system performance.