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HotSpot Internals

This wiki is written by and for programmers working on the HotSpot JVM system.

Contents

Intentions and non-intentions

This wiki contains:

• An architectural guide to the Runtime, Compiler, GC, Serviceability, etc.
• Details on performance techniques.
• A place to document likely future work (major refactorings or cleanups, new optimizations, etc.).
• Quick links to similar information in other places on the web.
  • http://java.sun.com/javase/technologies/hotspot ("Java SE HotSpot at a Glance")
  • http://openjdk.java.net/groups/hotspot/ (OpenJDK HotSpot Project home)
  • HotSpot-related research at the Johannes Kepler University Linz
• Information which, once written, is expected to remain accurate and relevant, as long as the related code remains stable.

Please look for the following types of information elsewhere:

• Not non-architectural or non-technical developer notes.
• Not an introduction or quick-start for working on the JVM. (TO DO: Put links here.)
• Not build instructions.
• Not a substitute for comments in the source code.
• Not a list of bugs or tasks.
• Not a blog, forum, or the comments section thereof.

Interesting tasks to do

• Extract links and info. from messages and blog postings, especially via hotspot-dev@openjdk.
• Extract links and info. from historical Sun mailing lists and wikis. (Sun engineers have to do this!)
• Write down understandings of major modules as they are (re-)acquired from trips through the code.

Who writes this wiki?

• We are using the Community Write pattern.
• There is no public write access, except for leaving page comments. You must be registered and logged in to leave comments.
• Please do add page comments when a page should answer your question but doesn't. (That means, potentially on any page.)
• The most effective page comments will include links to relevant email discussion threads, e.g., on the Hotspot compiler-dev list.
• Any member of the OpenJDK Hotspot Group or a related group should feel free to contribute.
• Actually, anybody with a (demonstrable) working knowledge of the Hotspot internals will be welcome to contribute content.
• Write permissions are not automatic until and unless the DBs get on speaking terms. If you think you should have write permission and don't contact the wiki administrator.