hotspot-gc-use Digest, Vol 46, Issue 9

Srinivas Ramakrishna ysr1729 at gmail.com
Fri Dec 30 21:26:43 UTC 2011


As of sometime ago the only way to control G1 initiation was indeed via
this flag, and
in fact G1 did not ergonomically kick off a collection based on other
factors (such as
promotion rate) like CMS does. This may or may not have changed in the last
two
months, but someone like John Cuthbertson or Tony Printezis would know for
sure.

-- ramki

On Fri, Dec 30, 2011 at 8:08 AM, Jon Masamitsu <jon.masamitsu at oracle.com>wrote:

> Not certain but I don't think there is an equivalent.
>
> On 12/30/2011 7:32 AM, Guy Korland wrote:
> > Thanks, I'll test it. Is there also something similar to -
> > UseCMSInitiatingOccupancyOnly ?
> >
> > Thanks,
> > Guy
> >
> >
> >
> > On Thu, Dec 29, 2011 at 4:28 PM, Jon Masamitsu<jon.masamitsu at oracle.com
> >wrote:
> >
> >> This is close to the CMS flag but is a percent of
> >> the entire heap (as opposed to the tenured
> >> generation for CMS).
> >>
> >> -XX:InitiatingHeapOccupancyPercent=NN
> >>
> >>
> >> On 12/29/11 01:45, Guy Korland wrote:
> >>
> >>   Yes, I'm familiar with this configuration for CMS.
> >> Is there a similar configuration for G1?
> >>
> >> Thanks,
> >> Guy
> >>
> >>
> >> On Thu, Dec 29, 2011 at 1:32 AM, Jon Masamitsu<jon.masamitsu at oracle.com
> >wrote:
> >>
> >>>
> >>> On 12/28/2011 1:17 PM, Guy Korland wrote:
> >>>
> >>>> Thanks for the answer, is there any chance you can also help with my
> >>>> other
> >>>> question?
> >>>> Is there a way with as with cms to control the "occupancy"?
> >>>>
> >>> If you mean the occupancy at which CMS starts  a collection, try
> >>> -XX:CMSInitiatingOccupancyFraction=NN where NN is the
> >>> percentage of the tenured generation at which a CMS collection
> >>> will start.
> >>>
> >>> If you mean something else, please ask again.
> >>>
> >>>
> >>> Thanks,
> >>>> Guy
> >>>>
> >>>>
> >>>> ---
> >>>>> Date: Tue, 27 Dec 2011 14:06:53 -0800
> >>>>> From: Jon Masamitsu<jon.masamitsu at oracle.com>
> >>>>> Subject: Re: Turning off generational GC
> >>>>> To: hotspot-gc-use at openjdk.java.net
> >>>>> Message-ID:<4EFA417D.4070009 at oracle.com>
> >>>>> Content-Type: text/plain; charset="iso-8859-1"
> >>>>>
> >>>>> For the hotspot garbage collectors the short answer is "no" there is
> no
> >>>>> way to
> >>>>> turn off generational GC.  I think it's even pretty deeply
> entrenched in
> >>>>> G1 which
> >>>>> is only logically generational.
> >>>>>
> >>>>> If CMS were not generational, in the best cause you would see pauses
> >>>>> on the order of 20ms.  Maybe much larger although less frequent.
> >>>>> More likely would be concurrent mode failures which would lead to
> >>>>> full GC's.
> >>>>>
> >>>>>
> >>>>> On 12/27/2011 1:20 PM, Guy Korland wrote:
> >>>>>
> >>>>>> Hi,
> >>>>>>
> >>>>>> I hope this is the right forum for this.
> >>>>>> It seems like no matter how small we set the young generation, it
> take
> >>>>>>
> >>>>> more
> >>>>> than 20ms.
> >>>>>> Is there a way turn off generational GC, especially in CMS?
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Guy
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> _______________________________________________
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> >>>>>> hotspot-gc-use at openjdk.java.net
> >>>>>> http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
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