In certain situations, crossing the JNI boundary can be advantageous. When data resides in "native" memory, outside the Java heap, the coordination of concurrent execution logic can be handled in Java, while the actual execution occurs in C++ or Rust. In this context, the negligible penalty for crossing the JNI boundary once per 10 million rows pales in comparison to the substantial benefits achievable through C++ optimization or CPU-specific assembly.
One of our distribution channels is Maven Central where we ship Java 11 compatible library. Embedded users preclude us from leveraging latest Java features.