luke warm methods?

Kirk Pepperdine kirk at
Wed Apr 21 14:35:16 PDT 2010


I've a situation where an application I'm looking at runs slow under low
load. After a number of tests the problem seems to be related to hotspot
optimizations. I ran a low level load test against the application for 8+
hours without any apparent meaningful optimization performed by hotspot.
Once the load was increased hotspot immediately kicks in and life it good.
Here's were it gets fun. I can put a short burst traffic on the server at
any time (including immediately after startup) and I will see an improvement
in response times. However, without that burst of traffic, response times
remain suboptimal. This happens even though the workload performed during
the 8+ hour run is greater than that performed during the burst.

More info, I watched the output from LogCompilation during a run. It showed
hotspot working for a while but then as expected, it stopped compiling
stuff. When I bursted traffic hotspot started compiling methods that had not
been compiled prior. Pretty much what I expected to see. I just don't know
why. It suggests that there is more than just the compile threshold
involved. I'd be happy if someone could share a plausable explination for
the observation?

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