GraalVM as pattern - work in progress

This is an attempt to describe GraalVM in pattern format. It’s motivated by this thread:

One of the best things about @graalvm is how it's gonna force us all to not use reflection.

— James Ward (@_JamesWard) December 15, 2020

Context

You are developing a JVM-based or (micro)service.

Problem

How do package my application for deployment?

Forces

• Commonly used frameworks should be supported
• Bugs should be detected as early as possible, e.g. unit tests on a developer’s laptop
• Compilation should be quick
• Test complexity should be minimized
• Test execution time should be minimized
• Resource utilization (e.g. on an edge device) should satisfy requirements
• Cost of deployment (e.g. AWS bill) should be within budget
• A fast startup time is important for some applications, especially serverless.

Solution

Package your application as a native image using GraalVM.

Resulting context

This approach has the following benefits:

• Reduced memory footprint

• Reduced startup time

This approach has the following drawbacks:

• Slow compilation
• GraalVM != JVM so application needs to be retested thoroughly
• Support for reflection, which is heavily used by many popular Java frameworks and libraries, is problematic. the GraalVM compiler must often be manually configured with a list of programming language elements that will be accessed using reflection. There is a risk that a program that works when using the JVM compiler, will fail when compiled with GraalVM. Consequently, the native executable will need to be thoroughly tested, which increases test complexity and execution time.

Related patterns

• Package the application as an executable JAR or WAR and use the JVM compiler

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