JDK6 GC Release notes
By jonthecollector on Feb 06, 2007
Edit done May 16, 2007.
Ryan and Tobais, sorry but I just saw your comments. I could not figure out how to reply with a comment (comment period being closed and I didn't want to mess with the settings too much) so I'm editting the blog to respond.
The line "CMS-concurrent-abortable-preclean" does not indicate a problem. The "abortable" only indicates that the current phase (precleaning) can be interrupted in order to start the next phase.
Yes, the UseParallelOldGC does imply UseParallelGC.