Container-aware heap sizing for OpenJDK

[Thomas Stüfe]

On Wed, Sep 14, 2022 at 11:53 AM Severin Gehwolf <sgehwolf at redhat.com>
wrote:

> Hi,
>
> On Tue, 2022-09-13 at 15:16 -0400, Jonathan Joo wrote:
> > Hello hotspot-dev and hotspot-gc-dev,
> >
> > My name is Jonathan, and I'm working on the Java Platform Team at
> > Google. Here, we are working on a project to address Java container
> > memory issues, as we noticed that a significant number of Java
> > servers hit container OOM issues due to people incorrectly tuning
> > their heap size with respect to the container size. Because our
> > containers have other RAM consumers which fluctuate over time, it is
> > often difficult to determine a priori what is an appropriate Xmx to
> > set for a particular server.
> >
> > We set about trying to solve this by dynamically adjusting the Java
> > heap/gc behavior based on the container usage information that we
> > pass into the JVM. We have seen promising results so far, reducing
> > container OOMs by a significant amount, and oftentimes also reducing
> > average heap usage (with the tradeoff of more CPU time spent doing
> > GC).
> >
> > Below (under the dotted line) is a more detailed explanation of our
> > initial approach. Does this sound like something that may be useful
> > for the general OpenJDK community? If so, would some of you be open
> > to further discussion? I would also like to better understand what
> > container environments look like outside of Google, to see how we
> > could modify our approach for the more general case.
>
> It seems an interesting proposal and I'd be interested in your work. A
> few questions:
>
>    1. How is AHS enabled? Is it on by default or is it opt-in?
>    2. Is the prototype working for all GCs available in OpenJDK or
>       specific to G1?
>    3. Would this be a Linux only feature?
>
> Thanks,
> Severin
>
>
>
... we are also interested. Can you describe the adjustment logic in more
detail or is there a public prototypec?

Cheers, Thomas
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