users@glassfish.java.net

Re: Debugging Glassfish CPU usage

From: <glassfish_at_javadesktop.org>
Date: Fri, 10 Apr 2009 01:34:12 PDT

Hi Jacob,

love a good CLI session... so, I setup a cron to run jmap -histo:live every hour and collected the data until the problem resurfaced. After looking at the dumps, the class using the most memory was [C, which from what I have discovered seems to mean char arrays. When I started collecting the data (which was hours after restarting the server, but hours before the symptoms surfaced again), [C was using approx. 700MB. When the CPU spikes began to occur, [C was using 1.3GB. The next most memory intensive class in each dump was [B, but the usage was roughly the same in all dumps, fluctuating less than 20MB.

So, any advice on how to determine what is creating / using / holding on to the char arrays? I'm going to try generating a heap dump and analyzing it with eclipse memory analyzer or jhat. Hopefully that will show me the enclosing object ...
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