147. Motivating and introducing Project Panama

Project Panama, or the Foreign Function & Memory (FFM) API, is an elegant way of saying goodbye to JNI. This project started in JDK 17 as JEP 412 (first incubator). It continued in JDK 18 as JEP 419 (second incubator), JDK 19 as JEP 424 (first preview), JDK 20 as JEP 434 (second preview), and JDK 21 as JEP 442 (third preview). This is where things are at the time of writing.

To understand the goals of this project, we have to talk about accessing off-heap memory from Java applications. By off-heap memory, we mean the memory that is outside the JVM heap and is not managed by the garbage collector.

Surfing off-heap is the job of JNI, JNA, and JNR. In one way or another, these APIs can work in off-heap land to handle different tasks. Among these tasks, we can enumerate the following:

• Use native libraries (for instance, some common libraries are Open CL/GL, CUDA, TensorFlow, Vulkan, OpenSSL, V8, BLAS, cuDNN, and so...