luke warm methods?

Vikram A vikram.account at
Thu Apr 29 02:30:54 PDT 2010

Please wait for Thomas's comments on this, but I would like to know...
Shouldn't TieredCompilation help perform better in such cases...


On Thu, Apr 29, 2010 at 2:32 PM, Ben Evans <ben.evans at> wrote:
> hotspot-dev-bounces at wrote on 22/04/2010 00:42:28:
>> We decay counters periodically since over time counters should only
>> go up so maybe that's the problem.  If you run with -XX:-
>> UseCounterDecay it will turn it off but all the other flags that
>> control it aren't available in product mode. This is certainly one
>> of the pathologies of an invocation counter based system with
>> relatively high thresholds.
> Just so I'm clear, this doesn't affect the compiled status of methods,
> right?
> What's being discussed here is that if an initial burst of activity results
> in a method being called say 4096 times (vs a threshold of 10000), then
> after 1 minute, then that method has had its invocation counter reduced to
> 1024.
> So the usual scenario whereby HotSpot reaches a steady state in terms of
> compilation activity can be disrupted by a sudden flurry of activity on
> rarely-used methods (which will be effectively cold due to the decay
> process), which pushes the invocation counts of these methods above
> compilation threshold. If these methods then go quiet again, then HS will
> *not* deoptimize and drop these methods back to interpreted mode, even if
> their invocation counters subsequently decay below threshold. Correct?
> Thanks,
> Ben
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> Ben Evans
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