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From Bryan Pendleton <bpendleton.de...@gmail.com>
Subject Re: Really need some help here please. I think I am having a problem with some sort of caching in Derby
Date Wed, 28 Mar 2012 13:48:35 GMT
> So what I found is that if I hit the “Perform GC” button on JvisualVM to perform an
explicit garbage collection, the same query
> that was taking 20 seconds or more instantaneously comes down to taking about 6 milliseconds.
Its processing time then starts to
> creep up back towards 20 seconds or more.

Is this an embedded configuration? Or are you looking at the Network Server?

If it's embedded, have you considered the possibility that it's something other
than Derby that's consuming the memory?

See if you can use a tool like this:


to get some overall histogram of memory consumption before and after
that explicit GC.

It might also make it easier to run your experiment under a smaller JVM,
with a smaller workload, because you'll have less overall data to record
and the analysis tools will be more responsive.

But the patterns may be less clear.



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