Java Virtual Machine Tools interface (JVMTI) was introduced in J2SE 1.5 (Tiger). This interface allows a profiling agent, written in the C programming language, to gather diagnostic information about the JVM such as memory usage, method invocations, and time spent within each method.
The JVMTI replaces an experimental interface called the JVMPI (Java Virtual Machine Profiling Interface). They are very similar, both providing a C interface to the JVM, but the JVMTI improves on JVMPI by providing a more complete interface to the profiling agent.