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From Kees Jan Koster <kjkos...@gmail.com>
Subject Re: what have i done to get 9 million cookies?
Date Wed, 07 Jan 2009 07:59:05 GMT
Dear Leon,

> i'm performing a jmap -histo:live on a tomcat which froze because of
> full (8GB) old space gen, and my top 10 looks like:
>
> num     #instances         #bytes  class name
> ----------------------------------------------
>   1:      19268009     2655683368  [C
>   2:      17410092     1392807360   
> org.apache.tomcat.util.buf.MessageBytes
>   3:      17411294     1114322816   
> org.apache.tomcat.util.buf.ByteChunk
>   4:      17410562      974991472   
> org.apache.tomcat.util.buf.CharChunk
>   5:      19275640      771025600  java.lang.String
>   6:       8697280      626204160  javax.servlet.http.Cookie
>   7:       8699584      417580032   
> org.apache.tomcat.util.http.MimeHeaderField
>   8:           188      134247456
> [Lorg.apache.tomcat.util.http.MimeHeaderField;
>   9:        198645      114493776  [Ljava.lang.Object;
>  10:         21303       30450504  [B
>
>
> So how did I manage to get almost 9 million of mimeheaderfields and
> cookies and 17 millions message bytes and chunks.
> During normal operation mode the number of the above doesn't increase
> except before the gc freeze.


You can try to generate a heap dump and analyse it using jhat. Trouble  
is, jhat requires insane amounts of memory. So for you 8GB dump you'd  
need something in the order of 32GB RAM for jhat.

If that is feasible, you could lower the memory limits on your  
machine, run the tests again to get a smaller dump with (hopefully)  
the same characteristics.
--
Kees Jan

http://java-monitor.com/forum/
kjkoster@kjkoster.org
06-51838192

The secret of success lies in the stability of the goal. -- Benjamin  
Disraeli


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