⚙️ GraalVM is one of the most exciting technologies in the Java ecosystem today. Let’s break it down simply and clearly.
✅ What is GraalVM?
GraalVM is a high-performance runtime that supports multiple languages and execution modes, built on the Java Virtual Machine (JVM).
It lets you run Java, JavaScript, Python, Ruby, R, WebAssembly, and even LLVM-based languages together, on the same VM.
🔹 Key Features of GraalVM
| Feature | Description |
|---|---|
| Polyglot support | Run Java + JavaScript + Python + Ruby, etc., in the same process |
| Native Image | Compile Java code into a standalone executable with fast startup & low memory |
| High-performance JIT | Replaces HotSpot’s JIT compiler with Graal, a modern optimizing compiler |
| Embeddable | Use GraalVM as a library inside your own JVM apps |
| Interop | Call JavaScript from Java, or Java from JavaScript, etc. |
🧱 What GraalVM Can Do
✅ 1. Run multiple languages in the same app:
// JavaScript code calling Java
var ArrayList = Java.type("java.util.ArrayList");
var list = new ArrayList();
list.add("Hello from Java!");
print(list.get(0));
✅ 2. Compile Java into native executables:
gu install native-image
native-image -jar myapp.jar
./myapp # fast startup, low memory
This is huge for microservices, serverless apps, or CLI tools. 🚀
✅ 3. Replace Nashorn for JavaScript scripting:
Context context = Context.create();
context.eval("js", "console.log('Hello from JavaScript in GraalVM!')");
🧠 Use Cases
| Use Case | GraalVM Feature |
|---|---|
| JavaScript scripting | JS engine replacing Nashorn |
| Native Java CLI tools | Native Image compilation |
| Fast microservices | Ahead-of-time compiled Spring/Quarkus apps |
| Language interop | Embed JS, Python, etc., in Java |
| Secure sandboxing | Isolated language contexts |
🔥 GraalVM vs Traditional JVM
| Feature | HotSpot JVM | GraalVM |
|---|---|---|
| Language support | Java/Kotlin/etc | Polyglot (Java, JS, Python, etc.) |
| JIT Compiler | C2 compiler | Graal compiler (modern, faster) |
| Native executable | ❌ No | ✅ Yes (via Native Image) |
| Startup speed | Moderate | ⚡ Extremely fast (native mode) |
🔧 How to Get It
- Website: https://www.graalvm.org
- Distributions: Community Edition (free) and Enterprise Edition (Oracle)