# GraalVM — Universal Polyglot Virtual Machine

> A high-performance JDK distribution and polyglot runtime from Oracle that compiles Java applications to native executables and runs multiple languages on a shared runtime.

## Install

Save as a script file and run:

# GraalVM — Universal Polyglot Virtual Machine

## Quick Use
```bash
# Install via SDKMAN
sdk install java 21.0.2-graal

# Compile a Java app to a native binary
javac App.java
native-image App
./app
```

## Introduction
GraalVM is an advanced JDK distribution by Oracle that includes a high-performance JIT compiler and a native-image tool for ahead-of-time compilation. It produces standalone executables with instant startup and low memory footprint, making it particularly suited for microservices and serverless workloads.

## What GraalVM Does
- Compiles Java applications to standalone native binaries with millisecond startup times
- Provides a high-performance Graal JIT compiler that replaces the C2 compiler in HotSpot
- Runs polyglot programs mixing Java, JavaScript, Python, Ruby, R, and LLVM-based languages
- Supports embedding guest languages into Java applications via the Truffle framework
- Offers a community edition (free) and an Oracle GraalVM edition with additional optimizations

## Architecture Overview
GraalVM is built on the HotSpot JVM with the Graal compiler replacing the server-side JIT. The native-image tool performs static analysis at build time, identifies reachable code through a closed-world assumption, and compiles it ahead-of-time via the Substrate VM into a self-contained binary. The Truffle framework provides a language implementation API where partial evaluation and compilation are handled automatically.

## Self-Hosting & Configuration
- Install via SDKMAN, download from graalvm.org, or use Docker images
- Use native-image to compile Spring Boot, Quarkus, or Micronaut apps to native binaries
- Configure reflection, resources, and JNI via JSON metadata files or the tracing agent
- Set heap limits with -Xmx for native images to control memory usage
- Use GraalVM Reachability Metadata Repository for third-party library compatibility

## Key Features
- Native executables start in under 10ms with a fraction of the memory of a JVM process
- Graal JIT compiler delivers competitive peak throughput for long-running applications
- Profile-guided optimization (PGO) further improves native-image runtime performance
- Closed-world analysis enables aggressive dead-code elimination and smaller binaries
- First-class integration with Quarkus, Micronaut, Spring Boot, and Helidon frameworks

## Comparison with Similar Tools
- **Standard OpenJDK** — better peak throughput for long-running apps but slower startup and higher memory
- **Eclipse OpenJ9** — optimized JVM with shared classes and fast startup, but no native-image equivalent
- **CRaC (Coordinated Restore at Checkpoint)** — checkpoint/restore for fast startup without AOT compilation trade-offs
- **Kotlin/Native** — compiles Kotlin to native code; limited to Kotlin, not the full JVM ecosystem

## FAQ
**Q: Does native-image support all Java libraries?**
A: Most libraries work, but those using reflection, dynamic proxies, or class loading require metadata configuration. Many popular frameworks ship with built-in GraalVM support.

**Q: How does startup time compare to a regular JVM?**
A: Native executables typically start in 5-50ms versus 1-10 seconds for a JVM application.

**Q: Is GraalVM free to use?**
A: GraalVM Community Edition is open source under GPLv2. Oracle GraalVM is free for development and production under the GraalVM Free Terms and Conditions.

**Q: Can I use GraalVM as a drop-in JDK replacement?**
A: Yes. GraalVM is a full JDK distribution and can run any Java application without modification.

## Sources
- https://github.com/oracle/graal
- https://www.graalvm.org/

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Source: https://tokrepo.com/en/workflows/36a8d26a-433f-11f1-9bc6-00163e2b0d79
Author: Script Depot