Major GC occurring before CMS occupancy fraction

Jon Masamitsu jon.masamitsu at oracle.com
Wed Nov 19 16:53:11 UTC 2014


On 11/18/2014 5:13 PM, Bernd Eckenfels 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?

If it looks like the occupancy of the perm gen is the issue, try setting
CMSTriggerPermRatio higher (default is 80) or try setting
CMSInitiatingPermOccupancyFraction to a high value (similar to
the way you choose CMSInitiatingOccupancyFraction.

Jon

> 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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