From JVM to Native Compilation with Spring Boot: What It Means and Why It Matters

Traditionally, Java developers have followed the same standard flow: write Java code, compile it to bytecode, and run it on the Java Virtual Machine (JVM). While this has worked well, it comes with trade-offs: slow startup, high memory usage, and a dependency on the JVM at runtime.

Now, thanks to tools like Spring Native and GraalVM, we can compile Spring Boot applications into native executables, binaries that start in milliseconds and consume a fraction of the memory. This lets Spring Boot apps run as fast and light as Quarkus, without having to change to a different framework.

In this article, I’ll explain what native compilation means, how it works, and why it makes a big difference for modern applications like microservices and serverless functions.

Traditional Java Compilation (JVM-Based)

Here’s how a traditional Java app works:

  1. You write Java code.
  2. The javac compiler turns it into bytecode (.class files).
  3. You package everything into a .jar.
  4. You run it with the JVM: java -jar myapp.jar

At runtime, the JVM translates bytecode into machine code by either interpreting it or compiling it on the fly using just-in-time (JIT) compilation.

Limitations

  • Slow startup (seconds)
  • Higher memory usage
  • Requires a JVM installed on the host machine

Native Compilation: What’s New?

With GraalVM Native Image, you can take your Java code and compile it into a native binary (like a .exe or Linux ELF file) that:

  • Runs without the JVM
  • Starts in milliseconds
  • Uses significantly less memory

This is called ahead-of-time (AOT) compilation, the code is compiled to native machine instructions before it’s run, not during runtime like with the JVM.

Spring Boot + Native Support

Starting with Spring Boot 3.x, Spring officially supports AOT + native image compilation through:

  • Spring AOT engine
  • Spring Native (based on GraalVM)

This means you can take your Spring Boot app and compile it into a self contained binary.

JVM vs Native: Key Differences

Feature JVM-based Spring Boot Native Spring Boot
Requires JVM Yes No
Startup time Slow (seconds) Fast (milliseconds)
Memory usage High (100MB+) Low (20–40MB)
Packaging .jar file Native executable (.exe, ELF)
Ideal for Monoliths, legacy apps Microservices, serverless, CLI

When Should You Use Native Compilation?

  • Microservices
  • Serverless functions (e.g., AWS Lambda, Cloud Run)
  • Applications with short lifecycle and high scalability demands

Not ideal for

  • Highly dynamic apps using a lot of runtime reflection (though Spring AOT is improving fast)

Conclusion

Native compilation brings a new level of performance and efficiency to Spring Boot applications. For the first time, you can write your app in Java and deploy it:

  1. With zero JVM dependency
  2. With instant startup
  3. Using less memory

Java is no longer just “write once, run anywhere”, now it’s also fast, lightweight, and cloud-ready.

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