I'm building this JEP for automatic heap sizing right now to address this when using ZGC: https://openjdk.org/jeps/8329758
I did in fact run exactly 200 JVMs, running a heterogeneous set of applications, and it ran totally fine. By totally fine I mean that the machine got rather starved of CPU and the programs run slowly due to having 12x more JVMs than cores, but they could all share the memory equally without blowing up anyway. I think it's looking rather promising.
