value of dense prefix address used?

[Jon Masamitsu]

Ramki,

I didn't find a product flag that would print the end of the dense prefix.
Don't know about jmx.

The phase accounting (PrintParallelOldGCPhaseTimes)
as you say is a good place to start.  The summary phase is
serial so look for an increase in that phase.   Does this pattern
repeat?

You could also try changing HeapMaximumCompactionInterval
and see if it affects the pattern.

Jon

On 2/17/2012 9:46 AM, Srinivas Ramakrishna wrote:
> Hi Jo{h}n, all --
>
> Is there some way i can get at the dense prefix value used for ParOld in
> each (major) collection? I couldn't find an obvious product flag for
> eliciting that info, but wondered if you knew/remembered.
> JMX would be fine too -- as long as the info can be obtained in a product
> build.
>
> I am seeing a curious looking log where one specific major gc seems to have
> greater user and real time, lower "parallelism" [=(user+sys)/real] and
> takes much longer than the rest of the ParOld's. It
> also lowers the footprint a tad more (but definitely not proportionately
> more vis-a-vis the user time ratios) than the gc's preceding (but not
> succeeding) that one, so one conjecture was that perhaps
> something happens with the dense prefix computation at that time and we
> somehow end up copying more. We'll see if we can get some data with
> printing the ParOld phase times, but i wondered if
> we might also be able to elicit the dense prefix address/size. I'll
> continue to dig around meanwhile.
>
> thanks for any info!
> -- ramki
>
>
>
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