Panama (https://openjdk.java.net/projects/panama/) will be replacing JNI very soon, and I don't think you're correct about vectorization. While I think Go has some good features, nothing about it is more "modern" than Java except in the most literal chronological sense; Java is more modern in almost every other meaningful sense. While you may need to tune the VM for critical tasks, in Go you don't need to tune, but rather just run slower.