<div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 14, 2022 at 11:53 AM Severin Gehwolf <<a href="mailto:sgehwolf@redhat.com">sgehwolf@redhat.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br>
<br>
On Tue, 2022-09-13 at 15:16 -0400, Jonathan Joo wrote:<br>
> Hello hotspot-dev and hotspot-gc-dev,<br>
> <br>
> My name is Jonathan, and I'm working on the Java Platform Team at<br>
> Google. Here, we are working on a project to address Java container<br>
> memory issues, as we noticed that a significant number of Java<br>
> servers hit container OOM issues due to people incorrectly tuning<br>
> their heap size with respect to the container size. Because our<br>
> containers have other RAM consumers which fluctuate over time, it is<br>
> often difficult to determine a priori what is an appropriate Xmx to<br>
> set for a particular server. <br>
> <br>
> We set about trying to solve this by dynamically adjusting the Java<br>
> heap/gc behavior based on the container usage information that we<br>
> pass into the JVM. We have seen promising results so far, reducing<br>
> container OOMs by a significant amount, and oftentimes also reducing<br>
> average heap usage (with the tradeoff of more CPU time spent doing<br>
> GC). <br>
> <br>
> Below (under the dotted line) is a more detailed explanation of our<br>
> initial approach. Does this sound like something that may be useful<br>
> for the general OpenJDK community? If so, would some of you be open<br>
> to further discussion? I would also like to better understand what<br>
> container environments look like outside of Google, to see how we<br>
> could modify our approach for the more general case.<br>
<br>
It seems an interesting proposal and I'd be interested in your work. A<br>
few questions:<br>
<br>
1. How is AHS enabled? Is it on by default or is it opt-in?<br>
2. Is the prototype working for all GCs available in OpenJDK or<br>
specific to G1?<br>
3. Would this be a Linux only feature?<br>
<br>
Thanks,<br>
Severin<br>
<br><br></blockquote><div><br></div><div>... we are also interested. Can you describe the adjustment logic in more detail or is there a public prototypec?</div><div><br></div><div>Cheers, Thomas</div></div></div>