jconsole question -- probably the wrong mailing list but here goes...

[Alan Bateman]

Stephen Ryan wrote:
> Hi,
>
> I was wondering if its possible to get the size of the classes loaded 
> from jConsole. Im seeing a lot of GC's in the Eden Space in a server 
> thats basically doing nothing. Im thinking that the jvm is trying to 
> load classes in there that are just too close to the size of that space.
>
> Any help appreciated!
>
> Stephen.
Classes are essentially allocated from the perm generation so I don't 
think this is what you are observing. Instead it is likely that you are 
observing the effect of the JMX agent in the target VM due to the 
polling by jconsole. Each time jconsole updates the display it must 
interact with agent in the agent VM so this means some objects are 
allocated which can lead to periodic scavenging that you observe. You 
can reduce the polling interval via jconsole's -interval=value option 
(interval is specified in seconds). The management interface for class 
loading doesn't include the size of the classes but if you try jstat 
then you can get this information (jstat -class <vmid>  for example).

-Alan.