HotSpot is the standard Java virtual machine used by both the Oracle and OpenJDK Java runtime environments.
HotSpot is the standard Java virtual machine used by both the Oracle and OpenJDK Java runtime environments for Java SE and EE environments.
This makes it the most widely deployed Java virtual machine in the world.
It is capable of running code from any language which can emit a Java .class file, as well as interpreted languages (e.g. JRuby) which have implemented their interpreters in Java (or another JVM language).
As of 2012, there are at least 200 languages which can run on top of the JVM - including Scala, Groovy, Clojure, JRuby, Jython and many smaller, niche languages.
HotSpot gets its name from the ability to dynamically profile running code and detect the "hot spots" of execution - the most commonly executing methods.
As, under most circumstances, programs spend most of their time in a small percentage of their methods, this focusing of optimization effort on the hot methods is very efficient.
HotSpot compiles and aggressively optimizes these hottest methods to highly platform-specific machine code which is specialized for the exact environment the code is running on.
This ability to use information about the runtime environment (precise instruction sets supported, memory and core configuration, etc) allows HotSpot to perform optimization tricks that are just not possible with a generic ahead-of-time strategy for "i386" or "i686" as is commonly seen in C/C++ environments.
This (along with the JVMs advanced memory management and garbage collection subsystem) makes the performance analysis of HotSpot-hosted programs more difficult compared to well-known techniques for C/C++. Direct comparison between the two environments is difficult - they each have individual strengths, and each has areas where they have definite advantages.
