Hi Luis.
I just discovered visualvm this morning in my quest. Its has some nice
features and all the same stuff that jconsole delivers as well.
Heres the top chunk of what jmap -histo delivers. Also the classes
loaded count is still increasing. Im starting to lean towards a bug in
the code of my webserver.
Size Count Class description
-------------------------------------------------------
70483456 210902 char[]
22539768 939157 java.lang.String
10608936 442039 java.util.HashMap$Entry
3876512 18922 java.util.HashMap$Entry[]
3823192 22119 * ConstMethodKlass
3046768 4349 byte[]
2724968 47155 java.lang.Object[] ...
Luis-Miguel Alventosa wrote:
Hi Stephen,
Could you try to use jmap -dump and/or jmap -histo to see the names
of the instances being created?
You could also have a look at VisualVM in order to profile the
application.
https://visualvm.dev.java.net
Regards,
Luis
> On 4/9/2008 3:24 PM, Stephen Ryan wrote:
>
> Hi Alan,
> Thanks for that but Im not sure its that at all. I've other servers
> being monitored and Ive never seen jConsole have this effect. I did a
> jmap on the server and saw some huge numbers. Im begining to think that
> theres bad code thats causing classes to be loaded too many times. The
> 'Classes' view in jConsole is showing me a constant rise in class
> numbers. I would have expected this to be more or less stable,
> considering that the server is serving about 4 requests per second. The
> CPU is pretty busy too.Busy garbage collecting the eden space I guess.
>
> I was considering increasing the eden space to see if that alleavates
> the problem, but if its a code problem, it wont help at all.
>
> Thanks!
> Stephen.
>
> Alan Bateman wrote:
>
>> 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.
--
Stephen Ryan
Principal QA Engineer
AOL Technologies Ireland Ltd.
3040 Lake Drive, City West Business Campus
Saggart, County Dublin, Ireland
Work: +353 1 4692115
[EMAIL PROTECTED]
"To destroy the concept of money, is going to take money" -Stang
