CMS collection keep working during holiday

Y Srinivas Ramakrishna Y.S.Ramakrishna at Sun.COM
Thu Oct 9 16:48:12 UTC 2008

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
> -- 
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