hi xu,

if you cannot find the "jhat" in the bin folder, most probably you were
referring to jre folder, instead of jdk folder.
i just checked it out, my jdk/bin folder has it, but not the case for my
jre/bin folder.

daniel
---
daniel baktiar
http://savinggaia.tritiumapps.com - saving the planet is everyone's
business!




On 23 November 2010 19:18, xu cheng <xcheng....@gmail.com> wrote:

>  hi, Chuck.Caldarale
> I referenced to these two links
> http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java
> http://blogs.sun.com/fkieviet/entry/how_to_fix_the_dreaded
> and do as the blog tolds, but failed to find the reason of the oom of my
> app...
> thanks though..
>
> by the way, do you have the the jhat the articals mentioned? I went to the
> jdk/bin,
> but the jhat there seems not work as the author mentioned.
>
>
>
>
> 2010/11/23 Daniel Baktiar <dbakt...@gmail.com>
>
> > hi charles,
> >
> > please allow me to disagree to that "hanging onto reference" as the main
> > issue.
> >
> > permgen space is garbage collector's specific issue, not general "hanging
> > onto reference issue". it is caused by redeployment, which is the
> metadata
> > for classes, marked to be permanent generation by the hotspot garbage
> > collector. when you deploy new classes, the class loader will introduce
> > memory usages that will also marked as permanent generation.
> >
> > permgen is oracle hotspot specific implementation issue. you won't get it
> > when you run on oracle jrockit (which performs just in time compilation),
> > for example.
> > ---
> > daniel baktiar
> > http://savinggaia.tritiumapps.com - saving the planet is everyone's
> > business!
> >
> >
> >
> >
> > On 23 November 2010 14:10, Caldarale, Charles R
> > <chuck.caldar...@unisys.com>wrote:
> >
> > > > From: xu cheng [mailto:xcheng....@gmail.com]
> > > > Subject: Re: OutOfMemoryError some time on some tomcat!!!!1
> > >
> > > > I just kept redeploying apps , and the perm gen keep
> > > > growing each time I deploy the same app. and when I
> > > > undeploy the app, the perm gen didn't clean the garbage
> > >
> > > Exactly the situation I suggested the other day: you have something
> > that's
> > > hanging onto a reference to an object from your webapp classes,
> > preventing
> > > the old webapp deployment from being garbage collected.  Again, read
> > this:
> > >
> > > http://wiki.apache.org/tomcat/FAQ/Memory
> > >
> > > Also, take a look at these:
> > >
> > > http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java
> > > http://blogs.sun.com/fkieviet/entry/how_to_fix_the_dreaded
> > >
> > >  - Chuck
> > >
> > >
> > > THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE
> PROPRIETARY
> > > MATERIAL and is thus for use only by the intended recipient. If you
> > received
> > > this in error, please contact the sender and delete the e-mail and its
> > > attachments from all computers.
> > >
> > >
> >
>

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