I guess we'll see when Java gets value types soon, but the Go people can answer that now; only problem is, I'm not sure people build as many and as-data-heavy applications in Go as they do in Java just yet. Also, realtime Java VMs do support arenas (even scoped arenas). So, I don't know the answer, but let's put it this way: I haven't heard anyone saying it isn't true -- and that would be a pretty big thing -- even though there should be enough indicators by now.