CMS collection keep working during holiday dragonken at
Fri Oct 10 05:58:55 UTC 2008

Thanks to all of you. It seems work after adding
-XX:+CMSClassUnloadingEnabled as you suggested.

So, why classloader create so many HashMap entries and Vector elements? It
seems that only a few people have this problem.

vm options:

-server -showversion\java.policy -Xms1536M
-Xmx1536M -XX:NewSize=256M -XX:+PrintGCDetails -XX:+PrintGCTaskTimeStamps
-XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -Xloggc:gc.log
-XX:+PrintReferenceGC -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC
-XX:+UseParNewGC -XX:SurvivorRatio=4 -XX:CMSInitiatingOccupancyFraction=55
-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled
-XX:MaxTenuringThreshold=1 -XX:SoftRefLRUPolicyMSPerMB=0

gc log: gc.log 


> 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
> >
> >

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