What Is GraalVM
A high-performance polyglot VM.
What Is GraalVM is a free Java Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What Is GraalVM
GraalVM is a high-performance JDK distribution built on a modern just-in-time compiler called Graal. It runs ordinary Java faster in many workloads and adds two headline capabilities: polyglot execution and ahead-of-time native compilation.
A Drop-In JDK
GraalVM is a full JDK. Your existing javac, java, and bytecode all work unchanged. The difference is the compiler underneath and the extra tools it ships, like native-image.
public class Main {
public static void main(String[] args) {
System.out.println("Runs the same on GraalVM as on any JDK");
System.out.println("Java: " + System.getProperty("java.version"));
}
}The Graal Compiler
The Graal JIT is written in Java itself. It performs aggressive optimizations such as advanced inlining, partial escape analysis, and speculative optimization, often beating the traditional C2 compiler on heavily abstracted, allocation-heavy code.
Polyglot with Truffle
GraalVM includes the Truffle framework, which lets multiple languages run on the same VM and even call each other. Implementations exist for JavaScript, Python, Ruby, R, and WebAssembly. Values can cross language boundaries with low overhead.
Polyglot Example (Conceptual)
With the polyglot API you create a Context and evaluate code in another language, then read the result back into Java. The classes live in org.graalvm.polyglot.
// Requires GraalVM polyglot runtime
import org.graalvm.polyglot.*;
public class Main {
public static void main(String[] args) {
try (Context ctx = Context.create()) {
Value sum = ctx.eval("js", "40 + 2");
System.out.println(sum.asInt());
}
}
}Native Image
The native-image tool compiles Java ahead of time into a standalone native executable. There is no JVM at runtime and no class loading or JIT warmup — the program starts in milliseconds.
Editions
GraalVM comes in a free Community Edition and an Oracle GraalVM distribution with additional optimizations. Both include native-image; for most learning and many production uses the community build is sufficient.
Why It Matters for Cloud
Fast startup and low memory make native images ideal for serverless functions, CLIs, and containers that scale to zero. A native Java service can start as quickly as a comparable Go binary, removing a long-standing JVM disadvantage.
JIT vs AOT
Two execution models coexist:
- JIT (the Graal compiler) optimizes at runtime using live profiling — best peak throughput for long-running servers.
- AOT (native-image) compiles before running — best startup and memory.
Framework Support
Modern frameworks like Spring Boot, Quarkus, and Micronaut ship first-class native-image support. They precompute configuration at build time so your application compiles cleanly to a native binary.
Choosing GraalVM
Adopt GraalVM when you want faster JIT throughput on abstraction-heavy code, need polyglot interop, or want native executables for fast-starting, low-memory deployments. It is a superset of a standard JDK, so adoption is low-risk.
Quick Check
Test your understanding of GraalVM.
Recap
You met GraalVM:
- A full JDK built on the high-performance Graal JIT compiler.
- Truffle enables polyglot execution and cross-language calls.
- native-image compiles Java ahead of time into native executables.
- JIT favors long-running throughput; AOT favors startup and memory.
- Frameworks like Spring Boot, Quarkus, and Micronaut support native builds.
Frequently asked questions
Is the “What Is GraalVM” lesson free?
Yes — the full text of “What Is GraalVM” is free to read here on the web, and the Java Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO.
What will I learn in “What Is GraalVM”?
A high-performance polyglot VM. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Java Academy?
No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “What Is GraalVM” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Java Academy lesson?
Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.