JFR can record a whole lot of events—from your applications to your JVM to the OS. It is a high performance, but low overhead profiler.

JFR extends the capabilities of event-based JVM tracing (JEP 167), which adds an initial set of events to HotSpot, to create events in Java. It also provides a high-performance backend to write data from the events to a binary format.

MC displays the application profiling data collected by JFR in a visual environment. You can select the category you want to analyze—from class loading to JVM internals (such as garbage collection), application threads, memory allocation, to complete application data analysis. We'll work with some of the MC features in this chapter (complete coverage of all of its features is beyond the scope of this book).