Hung JVM consuming 100% CPU
jon.masamitsu at oracle.com
Tue Mar 1 14:44:39 PST 2011
On 03/01/11 14:00, Charles K Pepperdine wrote:
>> The CMS concurrent collections are fast from what I've seen (on the
>> order of
>> the time between ParNew collections). The rate at which objects are
>> promoted is also low (maybe 3m per ParNew collection). CMS thinks it
>> can wait to start a concurrent collection. The fact that a
>> "promotion failure"
>> happened makes it look like fragmentation.
> Even with occupancy greater than 90%? I could very well be wrong about
> this but I thought that promotion failure meant just that, the young
> gen collector wasn't able to stuff objects up into tenured space. That
> didn't preclude fragmentation but in this case occupancy is 90% which
> IIRC is well above the OMG, I can't keep up lets trigger a parallel
> collection threshold.
I don't see CMSInitiatingOccupancyFraction on the command line.
-Xmx896m -Xss128k -XX:NewSize=384M -XX:MaxPermSize=96m
so CMS isn't using occupancy of the tenured gen to start a cycle. That
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