Jon Masamitsu's Weblog

  • Java
    February 6, 2007

JDK6 GC Release notes

Guest Author
Here's a couple of pointers to the GC section of the release notes
for JDK6.

"http://java.sun.com/javase/6/docs/technotes/guides/vm/par-compaction-6.html"> Parallel Compaction

Concurrent Mark Sweep Collector Enhancements

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.

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Comments ( 2 )
  • Ryan Krueger Tuesday, February 13, 2007
    Trying the new CMS in 1.6 and it seems to work nicely for a while but then it starts kicking out these CMS aborts. I can find nothing anywhere talking about what is happening. This happens over and over until a full GC happens. From what I can tell the CMS collector never completes and is therefore not doing anything except taking CPU time.
    CMS: abort preclean due to time 407.606: [CMS-concurrent-abortable-preclean: 0.149/5.058 secs]
  • Tobias Thursday, February 15, 2007
    Thanks! Could you please clarify if -XX:+UseParallelOldGC still needs a additional switch to enable the parallel GC of Eden or is that option implicit?
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