Reduce GitHub Action VM Size / Resource Consumption (Cost)

[vorburger]

The GitHub "Runner" which we (me) had set up in #2197 is "large".

The goal of this issue is to explore if it can reduced - ideally without slowing down builds.

[vorburger]

My analysis about this:

The https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources which this project originally (before my #2198 PR) used was a VM with 2-cores · 7 GB RAM · 14 GB SSD, and that was definitely too small, and didn't suffice.

CodeQL currently takes ~4-11'.

Build currently takes ~2-12'

#2295 will compare this with a VM with 4-cores · 16 GB RAM · 150 GB SSD...

#2296 will compare this with a VM with 8-cores · 32 GB RAM · 300 GB SSD...

[vorburger]

#2295 will compare this with a VM with 4-cores · 16 GB RAM · 150 GB SSD...

CodeQL took 9½' with this - about the same as (the high end of) with the huge VM.

Build took only 3' - but that's likely "wrong" (misleading), because all Gradle tasks are UP-TO-DATE; I probably need to make a trivial code change for this to be more realistic... or cherry-pick a random other PR to make a more sensible "real" comparison.

Kokoro failed with an unrelated problem; I've opened new #2297 about that.

#2296 will compare this with a VM with 8-cores · 32 GB RAM · 300 GB SSD...

CodeQL took 6' with this - a bit faster, but I'm not sure how significant this is.

Build again just 2' - same "problem" as above.

[vorburger]

or cherry-pick a random other PR to make a more sensible "real" comparison.

I'm using #2283 as a semi randomly chosen example (because it seems to have taken a bit longer to build, which is either a pure coincidence, or because the change of that dependency causes some real builds to happen) and have (temporarily) added that to the 2 PRs from above; the results are:

Build of #2283 with the very large VM as-is took ~8½'

CodeQL (ditto) took ~5'

#2295 will compare this with a VM with 4-cores · 16 GB RAM · 150 GB SSD...

Build with #2283 took 20'.

CodeQL (ditto) took 7'.

#2296 will compare this with a VM with 8-cores · 32 GB RAM · 300 GB SSD...

Build with #2283 took 13'.

CodeQL (ditto) took 5'.

[vorburger]

#2299 compare this with a VM with 16-cores · 64 GB RAM · 600 GB SSD:

Build with #2283 took 10'.

CodeQL (ditto) took 5'.

Based on these results, my suggestion would be to just go with the 8-cores one, for now.

I've therefore closed #2299 (16 cores) and #2295 (4 cores) and un-drafted #2296 (8 cores), after rm #2283 from it again.

[vorburger]

BTW The Xmx8g in https://github.com/google/android-fhir/blob/master/gradle.properties is relevant here; significantly more RAM won't be used by Gradle anyway with that.