Negative vCores in YARN with the Capacity Scheduler

Dmitry Tolpeko gives us a scenario where YARN ignores vCore availability:

You can expect that the total number of vCores available to YARN limits the number of containers you can run concurrently, that’s not true in some cases.

Let’s consider one of them – Capacity Scheduler with DefaultResourceCalculator (Memory only).

The name “Memory only” does give away the game a bit.