RFR (S): 6490394: G1: Allow heap shrinking / memory unmapping after reclaiming regions during Remark

[Thomas Schatzl]

Hi Ruslan,

On Tue, 2018-12-11 at 14:43 +0100, Ruslan Synytsky wrote:
> On Tue, 11 Dec 2018 at 10:42, Thomas Schatzl <
> thomas.schatzl at oracle.com> wrote:
> > On Mon, 2018-12-10 at 18:43 +0100, Ruslan Synytsky wrote:
> > > On Mon, 10 Dec 2018 at 16:48, Thomas Schatzl <
> > > thomas.schatzl at oracle.com> wrote:
> > > > On Mon, 2018-12-10 at 16:22 +0100, Ruslan Synytsky wrote:
> > > > > Dear Thomas and Sangheon, hope you are doing great. 
> > > > > 
> > > > > I just noticed an important improvement related to vertical
> > > > > scaling and would like to clarify details mentioned in the 
> > > > > release notes 
> > > > > 
> > >   [...]
> > > > > > This behavior may be disabled by changing minimum Java
> > > > > > heap size via the -Xms option.
> > > > > At the same time if a user adjusts Xms option then he/she 
> > > > > does not get this "smart behaviour" at all.
> > > > > 
> > > > 
> > > > This sentence should indicate that you can disable giving back
> > > > memory to the OS by modifying the Xms value. In particular, 
> > > > setting the Xms to the Xmx value - which is a rule that is 
> > > > part of the default heap sizing policy.
> > > 
> > > Then I think the wording in the release notes is confusing as 
> > > there is only one case when changing Xms disables giving memory 
> > > back, specifically when Xms = Xmx.
> > 
> > The behavior with Xms = Xmx corresponds to normal heap sizing
> > heuristics.
> > 
> > What would you prefer? Something like:
> > 
> > "This behavior may be disabled in accordance with default heap
> > sizing
> > policies by setting minimum Java heap size to maximum Java heap
> > size
> > via the -Xms option."
> 
> Yes, something like this sounds much better. 

I fixed it in the JIRA release not text. As far as I understand at some
point the official release note will be updated from it automatically.

Thanks,
  Thomas