MinHeapFreeRatio / MaxHeapFreeRatio

[Damon Hart-Davis]

Hi,

FWIW, I don't recall (though I'm not totally sure) the JVM ever giving memory back to the OS even when I tried (for other reasons) the serial collector in SE 6 Embedded.

Rgds

Damon


On 10 May 2012, at 17:41, Krystal Mok wrote:

> Hi Jon,
> 
> No, CMS doesn't do shrinking at all. The interface is there in the generational GC framework, but the implementation in CMS is left empty. I tried to implement shrinking in CMS once, but I ran out of time completing it, and found out that the original demand from our internal customer was supposed to be using ParallelGC, so I gave up.
> 
> Resizing generations to meet MinHeapFreeRatio / MaxHeapFreeRatio means shrinking has to be implemented in CMS, right?
> 
> - Kris
> 
> On Fri, May 11, 2012 at 12:31 AM, Jon Masamitsu <jon.masamitsu at oracle.com> wrote:
> Damon,
> 
>  From inspection of the code I think that CMS does not do a
> resizing of the heap after it does a System.gc().  That resizing
> would be the code that adjusts the generations for
> MinHeapFreeRatio / MaxHeapFreeRatio and returns
> memory to the OS.
> 
> I've created CR 7167923 to investigate this bug.
> 
> Jon
> 
> On 5/9/2012 2:34 AM, Damon Hart-Davis wrote:
> > Hi,
> >
> > No, because when I explicitly call System.gc() I want it to try as hard as it can, even to the point of stopping the world...
> >
> > Rgds
> >
> > Damon
> >
> >
> > On 9 May 2012, at 10:27, Jon Masamitsu wrote:
> >
> >> Damon,
> >>
> >> Do you turn on ExplicitGCInvokesConcurrent?
> >>
> >> Jon
> >>
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