Java in a docker container

[John Rose]

On Dec 15, 2016, at 1:45 AM, Volker Simonis <volker.simonis at gmail.com> wrote:
> 
> I think these are the reasons why other scripting or VM-based
> languages run better "by default" in container enviroments - they
> simple need fewer resources by default. But I think Java can be tuned
> in the same way - we just have to do it :)


Thanks, Volker; that's a good summary of our startup issues.

The CDS and AOT work are examples of our efforts to address these them.

In general, there is more to do in the direction of offloading startup work to configuration time.

(Relatedly, warmup work and resource sharing are also works in progress.)

Meanwhile, container-based computing uses lots of "glue" logic, and lots of it is in the form of short-run shell script calls which execute in vanilla execution environments.

Lightweight runtimes have the advantage of low startup (and teardown) overhead for such script-like calls.

Such runtimes are easy to choose for those jobs, and then they stick around for any bigger, longer-running jobs, such as monitoring software.

I think, for the bigger jobs, a bulletproof VM like Java's is preferable, but the lightweight ones are already on the job, because they were there on the thin end of the wedge.

I expect we can continue to make the JVM more and more useful at the same thin end of the wedge.

The general themes here are offloading startup work (metadata load, JIT, heap filling) and increased sharing of static resources.

— John