http://www.blogjava.net/lusm/archive/2007/08/08/135157.html

The HotSpot Group

The HotSpot group is comprised of developers involved in the design, implementation, and maintanence of the HotSpot virtual machine.

Introduction

Below you will find the the source code for the Java HotSpot virtual machine, the best Java virtual machine on the planet.

The HotSpot code base has been worked on by dozens of people, over the course of 10 years, so far. (That's good and bad.) It's big. There are nearly 1500 C/C++ header and source files, comprising almost 250,000 lines of code. In addition to the expected class loader, bytecode interpreter, and supporting runtime routines, you get two runtime compilers from bytecode to native instructions, 3 (or so) garbage collectors, and a set of high-performance runtime libraries for synchronization, etc.

Here's what you don't get with the source code: the class libraries that in combination with the virtual machine make a Java Runtime Environment (JRE) or Java Developers Kit (JDK). You can download those separately. You also don't get our amazing quality team that keeps the plane flying even while we work on it. You don't get our automated testing environment and labs full of fast machines, slow machines, uniprocessors and big iron, machines with various operating systems and compilers, etc. You don't get our performance team, to keep us from regressing. Or our partners and licensees who help us port and keep our code portable. And you don't get our zillions of happy (and not so happy) users, who keep us focused on what matters. If you want in on all of that you'll have to collaborate with us in the continued development of the platform.

下载：http://openjdk.java.net/groups/hotspot/