Interesting news from Oracle: on an announcement (yesterday) they communicated that JRockit is now free:
JRockit is now free (gratis) for development and internal production use on general purpose computers. Clarification: I stole this wording from the license text. These are the same terms that have been used for the Sun JDK for the last ten years or so.
Concerning commercial features, it is now possible buy licenses for JRockit standalone (until now it was not possible, only in bundles with other Oracle products):
Commercial features continue to require a commercial license. This includes most features currently in JRockit Mission Control, JRockit Real Time and JRockit Virtual Edition. Previously, it was only possible to get a commercial license for these features as part of Oracle products (such as WebLogic Server), they can now be purchased standalone for use with any Java application.
As a developer you are free to use Mission Control, as stated in the Q&A section:
Q: I am a developer, does this mean I can now use JRockit Mission Control for free?
A: Yes, there is no cost for development use. See the license for details.
If you are looking for a book, take a look at Oracle Jrockit: The Definitive Guide.
In a follow-up post, DonaldOJDK talks about the various JDKs…