Major GC occurring before CMS occupancy fraction

nitin sharma kumarsharma.nitin at gmail.com
Fri Dec 5 14:39:12 UTC 2014


Thanks for your response Bernd

Let me try to test with "PrintGCCause" argument.

Regards,
Nitin Kumar Sharma.


On Thu, Dec 4, 2014 at 8:18 PM, Bernd Eckenfels <ecki at zusammenkunft.net>
wrote:

> Hello,
>
> I see
>
> ParNews from 5GB/5GB -> 140MB
> CMS 4GB/10GB -> 1GB/10GB
>
> That would fit the 40% mark, but your args are different.
>
> I suspect some of the pools like code cache, perm gen or similiar
> beeing full. I am not sure if this is only logged with
> -XX:+PrintGCCause, but you can try. You might even be able to observe
> it with "jstat -gccause" live.
>
> Gruss
> Bernd
>
>
>
>
> Am Tue, 2 Dec 2014 10:38:22 -0500
> schrieb nitin sharma <kumarsharma.nitin at gmail.com>:
>
> > Hi Bernd,
> >
> > Apologies for such a late response. i got carried away in other
> > priorities ...
> >
> > PFA the truncated GC log for 24 hrs.. Kindly assist me to understand
> > why CMS collection is triggered well before "initial-occupancy"
> > fraction value.
> >
> > Regards,
> > Nitin Kumar Sharma.
> >
> >
> > On Tue, Nov 18, 2014 at 8:13 PM, Bernd Eckenfels
> > <ecki at zusammenkunft.net> wrote:
> >
> > > Hello,
> > >
> > > you need to provide verbose GC logs so we can say anything on that.
> > > But be aware that you might not get much help on ancient Java :)
> > >
> > > Can you try to set the initial perm size to the maximum size, to
> > > make sure resizes in this area do not trigger GC. And are you sure
> > > you are not confronted with RMI DGC runs?
> > >
> > > Gruss
> > > Bernd
> > >
> > >  Am Tue, 18
> > > Nov 2014 12:24:23 -0500 schrieb nitin sharma
> > > <kumarsharma.nitin at gmail.com>:
> > >
> > > > hi,
> > > >
> > > > I am facing the same issue.. We are using JDK 1.6. 0_23 and have
> > > > set Occupancy Fraction to 80% but i can see CMS triggered at much
> > > > below ration (around 53%)..
> > > >
> > > > is there a solution for same?
> > > >
> > > > I have used "-XX:CMSInitiatingOccupancyFraction=80
> > > > -XX:+UseCMSInitiatingOccupancyOnly" option...
> > > >
> > > > complete JVM argument set ==>
> > > >
> > > > /usr/java/jdk1.6.0_23/bin/java -server -Xms16384m -Xmx16384m
> > > > -XX:PermSize=512m -XX:MaxPermSize=1024m -XX:CompileThreshold=8000
> > > > -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps
> > > > -XX:+PrintGCTimeStamps -XX:+UseParNewGC -XX:MaxNewSize=6144m
> > > > -XX:NewSize=6144m -XX:+UseConcMarkSweepGC -XX:ParallelGCThreads=4
> > > > -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled
> > > > -XX:CMSInitiatingOccupancyFraction=80
> > > > -XX:+UseCMSInitiatingOccupancyOnly -DUseSunHttpHandler=true
> > > > -XX:+HeapDumpOnOutOfMemoryError
> > > >
> > > >
> > > >
> > > > Regards,
> > > > Nitin Kumar Sharma.
> > > >
> > >
> >
>
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