Sumatra was about GPU offload, not so much metacircular JVM. If you look at sumatra dev mailing list archive, you'll see the last email there states it's not in active development. The project appeared to have been driven by AMD, but they may have re-prioritized things.
I also don't think it's currently possible to write the bulk of the JVM in java, if you want comparable performance and memory footprint to Hotspot.
> I also don't think it's currently possible to write the bulk of the JVM in java, if you want comparable performance and memory footprint to Hotspot.
Better check Graal and JikesRVM research papers then.
One reason why reference JDK JIT doesn't get rewritten is the ROI.
Just check how long has taken to rewrite C# and VB.NET compilers while keeping the new compilers 1:1 compatible or the new RyuJIT and the multiple AOT compiler iterations in .NET land.
As already mentioned, Graal is just the JIT compiler, it's not the entire VM. JikesRVM is a research VM, which has different needs/characteristics from production JVMs.
I also don't think it's currently possible to write the bulk of the JVM in java, if you want comparable performance and memory footprint to Hotspot.