Number of Parallel GC Threads

Martin Buchholz martinrb at google.com
Sun Jan 25 22:53:58 UTC 2009


On Sat, Jan 24, 2009 at 14:13, Tony Printezis <Antonios.Printezis at sun.com>wrote:

>
> Regarding the CAM agent, you said correctly that they should somehow tune
> its parameters a bit better. And you are right; I would have reported it as
> a bug.
>


It's hard to fault an application for using the defaults.
Tuning should only be necessary to achieve top performance,
not to achieve reasonable performance.
If an application ends up not being a good citizen as a result of
decisions made by  the JVM, that's  a bug in the JVM.

In general, JDK engineers think in terms of peak performance
in benchmark-like settings.  I've been guilty of that myself.
We should try harder to have reasonable performance without
unreasonable resource consumption, by default.
Relatively few apps are in the "take over the machine" category.
Those few apps should be required to ask for such status via
a JVM flag.

I like the GC work done in the past few years by Matthew Hertz,
with an emphasis on finding the right balance for resource use
(particularly memory) by GC, especially adaptively.

Martin
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