Hung JVM consuming 100% CPU

Jon Masamitsu jon.masamitsu at
Tue Mar 1 16:29:47 UTC 2011

For 6692906 to be the problem there needs to be a
CMS concurrent phase in progress (marking, precleaning or
sweeping) and a minor collection running (with
UseParNewGC in use).  From the fragment of the gc log
I could not tell for sure (maybe it was in the ... removed)
but I don't think a concurrent phase was in progress
so I would say it is not 6692906).  Did you try
-XX:-UseParNewGC as was suggested?  Your minor
pauses are not particularly long so maybe you
could afford to try it.  6692906 will not happen
without UseParNewGC.   Note you need to turn of
UseParNewGC as it is the default for CMS.

Look back through the log for any other
ParNew (promotion failed) and see what happens
in those cases (in you find one).  2+ hours is too

The gentleman who would know best about this code
is out of the office until the end of the week.  I'll talk
to him about this to see if he remembers a recent
fix that I don't.

On 03/01/11 01:38, Bogdan Dimitriu wrote:
> Hi guys,
> We're having a problem with garbage collection as described here:
> (I
> apologise if posting links is not the right policy, but I prefer not to
> duplicate data).
> We are going to try an upgrade to JRE 6u24 soon, but reading the release
> notes for each of the versions since 6u20, I don't have much hope of
> this upgrade fixing the problem.
> I have searched a bit on the Java bugs database and I've come across
> something that looks similar to the problem I am experiencing:
>, but I'm not
> convinced this is exactly the same issue. This bug it seems will be
> fixed in 6u25 (which I've read will be released late March or early April).
> The reason I'm leaning towards thinking this is a JVM bug is the fact
> that the JVM can stay in the hung state (as described on the forum) for
> 2+ hours until we kill the process.
> I was hoping to get an idea about this from the source :), so any hints
> will be greatly appreciated.
> Thanks,
> Bogdan
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