1.6 jdk CMSPermGenSweepingEnbaled

Y Srinivas Ramakrishna Y.S.Ramakrishna at Sun.COM
Mon Jan 5 12:29:35 PST 2009


Hi Craig -- No, they are not enabled by default (even in 6.0),
so you'll need to explicitly enable +CMSClassUnloadingEnabled
to get the perm gen to be collected by CMS (as of
6.0 CMSPermGenSweepingEnabled became a no-op with a
suitable warning issued).

If you know the name of a specific JVM option,
i think there's some way you can have jconsole give you
the value from a running JVM. Others on this list might
be able to provide details on how to get jconsole to
reveal these secrets. (One would hope jinfo might have
a flag/query/option for such as well.)

I'm cross-posting into the serviceability alias
where the latter part of this discussion likely belongs
and where you'll get more concrete information than
my musings above.

-- ramki

----- Original Message -----
From: craig yeldell <ycraig at cysystems.com>
Date: Monday, January 5, 2009 12:18 pm
Subject: 1.6 jdk CMSPermGenSweepingEnbaled
To: hotspot-gc-use at openjdk.java.net


> I have run into some PermGen OOM issues, and thought I remember  
> reading that the following args are enabled in the 1.6 jdk.  Does  
> anyone know where I can find the info on the default settings?
> 
> CMSPermGenSweepingEnabled
> CMSClassUnloadingEnabled
> 
> 
> 1.6.0_10 64bit
> 
> Regards,
> Craig
> _______________________________________________
> hotspot-gc-use mailing list
> hotspot-gc-use at openjdk.java.net
> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use



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