Avoiding the Young Generation Guarantee

[Alex Aisinzon]

Srinivas

I thank you for the additional info.
I was planning on testing UseParallelOldGC in our performance testing
environment.
I had noticed that this option was used in some Sun JDK SPECJBB2005
benchmarks
(http://www.spec.org/jbb2005/results/res2006q1/jbb2005-20060117-00062.ht
ml by example)
The parallel nature of the young and tenured generation collection makes
it a very good candidate for scaling across many processors and with
large heaps, which is what I am looking for.

Alex A

-----Original Message-----
From: Y Srinivas Ramakrishna [mailto:Y.S.Ramakrishna at Sun.COM] 
Sent: Monday, March 10, 2008 12:43 PM
To: Alex Aisinzon
Cc: hotspot-gc-use at openjdk.java.net
Subject: Re: RE: Avoiding the Young Generation Guarantee


Relatedly, you might also want to (separately) try the +UseParallelGC
collector
-- in later versions of 5 (5u8 and later, AFAIR) it provides a
parallel old collector as well: -XX:+UseParallelOldGC.
Even otherwise, +UseParallelGC provides adaptive/dynamic
sizing of the generations, which might provide you with better
throughput than the static hand-tuning you would typically do
with +UseParNewGC.

The GC tuning guide provides further details (see "Ergonomics"
and "Parallel Compaction").

-- ramki

----- Original Message -----
From: Alex Aisinzon <aaisinzon at guidewire.com>
Date: Monday, March 10, 2008 12:36 pm
Subject: RE: Avoiding the Young Generation Guarantee
To: Y Srinivas Ramakrishna <Y.S.Ramakrishna at Sun.COM>
Cc: hotspot-gc-use at openjdk.java.net


> Srinivas
> 
> I thank you for the pointer. I will try that option very soon and
report
> on it.
> 
> Regards
> 
> Alex Aisinzon
> 
> -----Original Message-----
> From: Y Srinivas Ramakrishna [mailto:Y.S.Ramakrishna at Sun.COM] 
> Sent: Monday, March 10, 2008 12:24 PM
> To: Alex Aisinzon
> Cc: hotspot-gc-use at openjdk.java.net
> Subject: Re: Avoiding the Young Generation Guarantee
> 
> 
> -XX:+HandlePromotionFailure should allow you to circumvent the
pessimal
> guarantee.
> (AFAIR, that was made the default behaviour in 6.0, but was not in
5.0,
> unless
> you also used the CMS collector; but the history is a bit vague in my
> mind,
> so you should of course check this rather than take my word for it.)
> 
> -- ramki
> 
> ----- Original Message -----
> From: Alex Aisinzon <aaisinzon at guidewire.com>
> Date: Monday, March 10, 2008 11:50 am
> Subject: Avoiding the Young Generation Guarantee
> To: hotspot-gc-use at openjdk.java.net
> 
> 
> > All
> > 
> >  
> > 
> > Our application scales very well when more memory is allocated to
it.
> > 
> > The Young Generation Guarantee limits that scalability as it forces
> Full
> > GC while plenty of space is still available in the tenured space.
> > 
> > That guarantee forces us to use relatively smaller nurseries.
> > 
> >  
> >
>
http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html#0.0.0.0.%20Young
> > %20Generation%20Guarantee%7Coutline infers that this guarantee only
> > applies to the serial collector but I see it too with the parallel
new
> > collector.
> > 
> > Maybe I am confused in the collector terminology.
> > 
> > Could someone tell me how I can disable the young generation
> guarantee?
> > 
> >  
> > 
> > Thanks in advance
> > 
> >  
> > 
> > Alex A
> > 
> >  
> > 
> > I have enclosed a snippet of the GC logs for analysis purposes.
> > 
> > _______________________________________________
> > hotspot-gc-use mailing list
> > hotspot-gc-use at openjdk.java.net
> > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
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