The relevance is that even a 175 LOC project in Java takes up enormous memory and disk footprint -- that the JVM is this super-heavyweight thing that's really just inherently inappropriate for a lot of applications.
_This particular_ 175 LOC Java project takes up an enormous amount of memory. For all you know it was just coded poorly and the Go one is a bit more reasonable.
> the JVM is this super-heavyweight thing that's really just inherently inappropriate for a lot of applications.
The JVM introduces overhead but not so much that you can make these sorts of extrapolations.
1. the JVM itself imposes a high floor (hotspot, many shared libs loaded, ...)
2. the Java language is full of overhead at every level (boxed types are a pet peeve of mine)
3. the Java ecosystem has a tendency to regard memory as an inexhaustible resource, which lead a lot of waste in many 3rd party libraries
Optimization was the original goal, increased maintainability was a pleasant result.
Value types would help so much with this issue. I know they're coming one day. I hope Java/JVM can replicate memory efficiency and cache coherence of C++ std::vector for small objects.
I'm not going to install the JDK just to verify, but feel free to report back if you get different results.
Not sure what the golang overhead is, by comparison.
There are enough solutions (e.g. servlet containers) where you can run multiple services in one VM, with isolation, and security hardening (using security manager).
With regards to memory footprint - the difference here is that Java uses a minimum and maximum heap size that can be tuned with parameters. This has downsides (typically more memory use) and upsides (upper bound on the maximum memory use of a process).
Most notably, all services will share the same heap, so one ill-behaved service can bring down all the other services. The only way to prevent this, is to run each service in a separate VM.
And at that point, you are once again comparing one Go runtime per service with one JVM per service.
If you're running a Go app in a container, you can use also tune the upper bound on memory use by restricting the available memory for the container.
The whole Netflix is based on the JVM and Java. They are enormously big, they have high CPU and I/O requirements in many cases, and yet, they manage well on Java.
I'm not a big fan of Java as language (to say the least), but the JVM as a runtime is very-very sophisticated.
You just need the Server JRE which is 57MB tarball + 157MB uncompressed.