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    <p>From the error message it appears that the JVM is using the parallel scavenger algorithm for garbage collection. The message is dumped along with an OOME error when <a href="http://java.sun.com/javase/technologies/hotspot/gc/gc_tuning_6.html#par_gc.oom" rel="nofollow noreferrer">a lot of time is spent on GC, but not a lot of the heap is recovered</a>.</p> <p>The document from Sun does not specify if the 98% of the total time consumed is to be read as 98% of the CPU utilization of the process or that of the CPU itself. In either case, I have to draw the following inferences (with limited information):</p> <ul> <li>The garbage collector or the JVM process does not have enough CPU utilization, most likely due to other processes consuming CPU at the same time.</li> <li>The garbage collector does not have enough CPU utilization since it is a low priority thread, and another memory intensive (but not CPU intensive) thread in the JVM is doing work at the same time, which results in the failure to de-allocate memory.</li> </ul> <p>Based on the above inferences (all, one or none of them could be true), it would be worthwhile to correlate the graph that you're obtained with the runtime behavior of the application as far as users are concerned. In other words, you might find it useful to determine if other processes are kicked off (when your problem occurs), or the part of the application that is in operation (again, when the problem occurs).</p> <p>In any case, the page referenced above, does give an option to disable the GC overhead limit used by the GC algorithm.</p> <p><strong>EDIT:</strong> If the problem occurs periodically, and can be reproduced, it might turn out to be a memory leak, otherwise (i.e. it occurs sporadically), you are better off tuning the GC algorithm or even changing it.</p>
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    1. COThe first bullet point doesn't make sense to me, as the cpu usage drops. The second one seems plausible, but I still don't understand why the memory usage seems to reach some kind of maximum which it can't pass? I'd rather not change the GC overhead limit as I have a feeling that it will only address the symptom and not the cause.
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    2. COThe first point makes sense if your graph is reporting only the JVM's CPU usage, and not other processes. As for the flag on GC overhead limit, well that just disables the overhead; you cannot change it. Coming to the second point, it might help if you can determine whether you've hit a high water mark. What I meant to say is that it is quite possible that the graph is not depicting the entire heap, and possibly only a portion of it (does it include permgen as well?).
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    3. COOkay, I understand what you mean with point one. This graph is only for the JVM's CPU usage and the system is dedicated to this application. The graph does not include permgen, so are you suggesting that it might be the permgen space which causes the OOME? What could affect permgen space over time, in the past the only problems I've had with permgen was with loading and unloading of classes?
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