Shenandoah: How small is small?

[Martijn Verburg]

There's a specific shenandoah-dev list - you may get a more accurate
response there as it's a moving target.

Cheers,
Martijn

On 15 November 2016 at 17:19, <org.openjdk at io7m.com> wrote:

> Hello.
>
> I've been watching the development of Shenandoah since it began. As a
> developer of software with mildly soft-realtime requirements (games,
> primarily), I'm always eager to see advances that can reduce GC pause
> times. Although right now I don't have a GC problem (typically, my
> pauses for minor GCs are well below 16ms and therefore are not
> perceptible given the usual 30hz/60hz game loop), I still feel that I
> have to be more conscious of allocation rates than feels natural in
> order to avoid producing too much garbage. I sometimes find myself
> avoiding better abstractions and immutable objects simply because I
> want to avoid allocations. Escape analysis helps, but sometimes those
> objects really do need to hang around. Value types will also help!
>
> I've read in JEP 189 that Shenandoah is intended to try to reduce pause
> times on +100gb heaps, and a rather outdated blog post online [0]
> suggested that a 512mb heap is simply too small to run at all. The
> software I write is written under the general assumption that 1GB of
> memory will be a minimum requirement - this includes both the JVM heap
> and any allocated native memory.
>
> Right now I'm still using ParNew, although I'll likely move to G1 if it
> becomes the default in JDK9. Is Shenandoah likely to be an improvement
> for my use case?
>
> Regards,
> Mark
>
> [0] https://www.jclarity.com/2014/03/12/shenandoah-experiment-1-
> will-it-run-pcgen/
>
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