oracle/graal

GraalVM is a Java Development Kit, meaning you can use it as a drop-in replacement for the regular kit Java developers already work with in their editor. What makes it different is that it can compile a Java application ahead of time into a single standalone binary, called a native executable. The README's tagline says these executables start instantly, provide peak performance with no warmup, and use fewer resources. A normal Java program is first turned into a portable intermediate form, then a runtime translates it into machine code as the program runs. That translation, plus the warm-up the runtime needs, costs startup time and memory. GraalVM's approach, called ahead-of-time (AOT) compilation, does the translation up front and bakes the result straight into a binary, so there is no runtime translation step left at start. The repository bundles several pieces that make this possible: the Graal compiler itself, written in Java, Native Image, which produces the standalone binaries, the Truffle framework for building new languages and tools on top of the platform, and engines that let GraalVM also run programs written in other languages, including LLVM bitcode through Sulong and WebAssembly through GraalWasm. JavaScript and Python support live in related projects. You would reach for GraalVM if you are shipping a Java application where slow startup or large memory use is a problem, for example a command-line tool, a serverless function, or a microservice that needs to scale up quickly. It is also useful if you want to run code written in several different languages on a single shared runtime.