RFR [14]: 8232207: Linux os::available_memory re-reads cgroup configuration on every invocation

[Claes Redestad]

On 2019-10-15 18:11, Severin Gehwolf wrote:
>> Webrev:http://cr.openjdk.java.net/~redestad/8232207/open.00/
> This looks fine to me.

Thanks, Severin!

> 
> It's a reasonable compromise between caching and getting updates from
> the container runtime. FWIW, this also helps the jshell case (as
> detailed in JDK-8227006).
> 
> Crazy idea: Perhaps it'd be worth turning those 20ms into a JVM
> parameter. Accept -1 for caching until the JVM restarts.

Not too crazy.

> 
> Note that from an OpenShift perspective, config changes == container
> restart, ergo JVM restart. So there is no point in actually re-reading
> the limits.

This is an interesting data point. I've always been curious where the
requirement originated that says the JVM container support must adjust
dynamically to container configuration changes?

If the typical scenario is a static configuration then perhaps that
would have been a better default. A fully adaptive mode (with the
overheads that comes) sounds like something that should be an opt-in.

/Claes