Exploring GraalVM: A New Era in the Java Ecosystem

Java has been a cornerstone of software development for decades, renowned for its portability, robustness, and vast ecosystem. However, like any technology, it has faced a series of challenges over the years—ranging from performance bottlenecks to the increasingly complex demands of polyglot programming. In this article, we’ll dive into the Java world before GraalVM, discuss why GraalVM was conceived, explore its benefits and downsides, and provide a complete example of using GraalVM with Spring Boot.

The Java World Before GraalVM

Before GraalVM entered the scene, the Java ecosystem was primarily powered by the HotSpot JVM. This was (and still is) a reliable and performant virtual machine, but it came with a few challenges:

1. Startup Times: Traditional JVMs often suffer from slow startup times. For long-running applications (like large enterprise services), this might not be a big issue, but for serverless or microservices architectures that spin up new instances frequently, slow startup can be problematic.
2. Memory Consumption: Java applications can use significant amounts of memory compared to some other languages. While this might be manageable in a monolithic environment, it becomes expensive and less efficient in microservices or cloud-native setups, where resource usage directly translates to costs.
3. Polyglot Complexity: Java developers often need to integrate with code written in other languages like JavaScript, Python, or Ruby. Without a unifying runtime, developers had to juggle multiple platforms and bridges, complicating the development and deployment process.
4. Performance Profile: Java’s Just-In-Time (JIT) compilation is sophisticated, but it can take time for the JVM to optimize code at runtime. For short-lived processes, the performance gains of JIT might not fully materialize before the process ends.

These hurdles spurred the search for more efficient and versatile solutions—paving the way for GraalVM.

The Birth of GraalVM: Idea and Definition

What is GraalVM?

GraalVM is a high-performance virtual machine designed to execute applications written not only in Java but also in other languages like JavaScript, Python, Ruby, and even LLVM-based languages like C and C++. Its development began as an experimental project by Oracle Labs, aiming to solve some of the inherent limitations in traditional JVM setups. Over time, it evolved into a production-ready solution, offering ahead-of-time (AOT) compilation and seamless polyglot capabilities.

Key Innovations:

1. Faster Startup Times: By compiling Java code ahead of time into native executables, GraalVM-based applications initialize much faster, which is especially useful in serverless and microservices environments.
2. Reduced Memory Usage: Native images typically consume less memory than JIT-compiled JVM processes, offering cost savings in cloud-based deployments.
3. Polyglot Support: With GraalVM, you can combine multiple programming languages in a single runtime, seamlessly calling functions or classes across languages without complex bridges.
4. High Performance: GraalVM uses an advanced Just-In-Time compiler for code running in JVM mode, offering performance optimizations that can be on par with or even surpass traditional HotSpot in some scenarios.
5. Ecosystem Compatibility: GraalVM remains compatible with the broader Java ecosystem. Existing libraries and frameworks can often be adapted for GraalVM with minimal effort.

Disadvantages of GraalVM

1. Longer Native Image Build Times: Although you get faster startup, the process of generating a native image can be time-consuming. This might slow down development cycles if you rely heavily on repeated builds.
2. Complex Configuration: Some libraries that rely on reflection, dynamic class loading, or other JVM-specific features may require additional configurations or substitutions to work smoothly with GraalVM native images.
3. Limited Tooling vs. Standard JVM: While the ecosystem is growing, some specialized debugging or profiling tools are not as robust as the classic JVM equivalents.
4. Community Maturity: Although GraalVM is backed by major organizations, it is still relatively newer in the enterprise space. Some organizations may be cautious about adopting it broadly until they see a larger community adoption.

A Complete Example: Using GraalVM with Spring Boot

Below is a step-by-step guide to building a native executable for a Spring Boot application using GraalVM on Ubuntu. We’ll walk through a simple “Hello, GraalVM!” application and detail the necessary installation steps.

Step 1: Install GraalVM on Ubuntu

Download GraalVM

• Visit the official GraalVM website and download the latest Linux (tar.gz) distribution.
• Move the downloaded file to a preferred location (e.g., /opt).

Extract and Set JAVA_HOME

• Extract the tar.gz file

sudo tar -xzf graalvm-ce-java17-linux-amd64-*.tar.gz -C /opt        

• Replace graalvm-ce-java17-linux-amd64-* with the exact filename you downloaded.
• Point JAVA_HOME to the extracted GraalVM folder and update your PATH

export JAVA_HOME=/opt/graalvm-ce-java17-<version> export PATH=$JAVA_HOME/bin:$PATH        

• You can add these lines to your ~/.bashrc (or ~/.zshrc) to make them permanent.

Install Required Build Tools

sudo apt-get update 
sudo apt-get install -y build-essential libz-dev        

Install the Native Image Component

• GraalVM comes with the gu (Graal Updater) utility to install additional components. Run:

gu install native-image        

• This step is crucial for creating native executables.

Verify Installation

java -version        

Make sure it prints something like “GraalVM CE” in the output, indicating that your Java environment is now GraalVM.

Step 2: Set Up Your Spring Boot Project

Create a Simple Spring Boot App

• Use Spring Initializr to generate a basic Maven project with Spring Boot. Include the Spring Web starter.

Configure pom.xml

• Add the dependencies and plugins for Spring Native and GraalVM Native Image:

<project>
    <!-- ... Other configurations ... -->
    <properties>
        <java.version>17</java.version>
        <spring-native.version>0.12.1</spring-native.version>
    </properties>

    <dependencies>
        <!-- Spring Boot Starter Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        
        <!-- Spring Native dependency (for older versions) -->
        <dependency>
            <groupId>org.springframework.experimental</groupId>
            <artifactId>spring-native</artifactId>
            <version>${spring-native.version}</version>
        </dependency>
        
        <!-- GraalVM Native Image support -->
        <dependency>
            <groupId>org.graalvm.nativeimage</groupId>
            <artifactId>svm</artifactId>
            <version>21.3.0</version> <!-- Example version -->
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- Spring AOT Plugin -->
            <plugin>
                <groupId>org.springframework.experimental</groupId>
                <artifactId>spring-aot-maven-plugin</artifactId>
                <version>${spring-native.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <!-- Native Image Maven Plugin -->
            <plugin>
                <groupId>org.graalvm.buildtools</groupId>
                <artifactId>native-maven-plugin</artifactId>
                <version>0.9.9</version> <!-- Example version -->
                <executions>
                    <execution>
                        <goals>
                            <goal>build</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>        

Step 3: Create a Simple Controller

@RestController
public class HelloController {

    @GetMapping("/hello")
    public String helloGraalVM() {
        return "Hello, GraalVM!";
    }
}        

Step 4: Build the Native Image

Clean and Package

From the project’s root directory, run:

./mvnw clean package -Pnative        

• This uses the Maven native profile (defined by the plugins above) to build a native executable.

Check the Generated Executable

• If everything succeeds, you should find an executable (e.g., myapp) inside the target folder (or a similar name depending on your project).

Step 5: Run the Native Executable

./target/myapp        

Your application should start almost instantly—much faster than it would under a traditional JVM. Visit https://localhost:8080/hello in your browser, and you’ll see:

Hello, GraalVM!        

Conclusion

GraalVM represents a significant milestone in the evolution of the Java ecosystem. It tackles longstanding issues such as slow startup times and high memory consumption, while embracing a polyglot future that many modern applications require. Although it comes with its own set of drawbacks—like more complex configuration and longer build times—the payoff in performance and flexibility makes GraalVM a compelling choice for many organizations.

As cloud-based services and microservices architectures continue to demand faster, lighter, and more flexible runtimes, GraalVM is likely to gain even broader traction. Whether you’re optimizing an existing Java application or pioneering new projects in multiple languages, GraalVM opens up possibilities that simply weren’t feasible with traditional JVMs alone.