CMS collection keep working during holiday

kirk kirk.pepperdine at
Thu Oct 9 17:11:27 UTC 2008

of course... look at this

VM optoins:\java.policy -Xms1536M -Xmx1536M
-XX:NewSize=256M -XX:+PrintGCDetails -XX:+PrintGCTaskTimeStamps
-XX:+PrintHeapAtGC -Xloggc:gc.log -XX:+PrintReferenceGC
-XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC
-XX:SurvivorRatio=4 -XX:CMSInitiatingOccupancyFraction=55
-XX:TargetSurvivorRatio=90 -XX:SoftRefLRUPolicyMSPerMB=0 

Perm space is ignored! Does he need to add -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled


Y Srinivas Ramakrishna wrote:
> The mention of class loaders below reminds me to remind you that
> CMS by default will not collect class objects. To force CMS
> to collect classes in the perm gen, you would want to
> -XX:+CMSClassUnloadingEnabled. Try to see if that made any
> difference to the apparent inability of CMS to collect
> those apparently otherwise unreachable objects.
> -- ramki
> ----- Original Message -----
> From: "Ken-- at" <dragonken at>
> Date: Thursday, October 9, 2008 3:10 am
> Subject: Re: CMS collection keep working during holiday
> To: hotspot-gc-dev at
>> Hi,
>> I have jhat the vm heap but I don't know how to trace the problem. I tried
>> to click HashMap$Entry / HashMap and there is so many instances and 
>> halt my
>> browser. I found many references to HashMap are
>> com.sun.jmx.remote.util.OrderClassLoaders at 0x49448a18 (54 bytes) : field
>> packages
>> sun.rmi.server.LoaderHandler$Loader at 0x17be85d0 (75 bytes) : field packages
>> at 0x40b740e8 (18 bytes) : field 
>> perms
>> Up to now, I believe my application has no memory leaks as my 
>> application is
>> running very well without CMS collector and DisableExplicitGC. But I need
>> CMS and DisableExplicitGC in order to have short gc pause time.
>> There must be somewhere fool the CMS collector. Any idea to shoot the
>> problem? Is that my application problem or jvm itself?
>> Thanks and Best Regards,
>> Ken
>> -- 
>> View this message in context:
>> Sent from the OpenJDK Hotspot Garbage Collection mailing list archive 
>> at

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