How I Achieved Incredibly fast Java Micronaut Service Startup Times with GraalVM

Despite my Micronaut Java service having a fast startup time, I wanted to see if I could get it starting even fast for production. The short answer was YES.

In order to do this, I used GraalVM - an advanced optimizing compiler with the ability to generate executables - even for a Java application.

First I used https://sdkman.io to install any GraalVM.

sdk use java 20.0.0.r11-grl

Then I started my micronaut service:

CFE-NB-1023:vin-check bporter$ ./gradlew run

> Task :run
OpenJDK 64-Bit Server VM warning: forcing TieredStopAtLevel to full optimization because JVMCI is enabled
13:26:30.738 [main] INFO  io.micronaut.runtime.Micronaut - 
Startup completed in 760ms. Server Running: http://localhost:5000

It started in 760ms - which still is not bad for a Java service starting using a JIT.

Then I compiled the executable with GraalVM and got it down to 32ms!!

CFE-NB-1023:vin-check bporter$ ./micronaut-graal-app 
13:26:40.739 [main] INFO  io.micronaut.runtime.Micronaut - 
Startup completed in 32ms. Server Running: http://localhost:5000

In order to achieve that, I followed the instructions on this page https://guides.micronaut.io/micronaut-creating-first-graal-app/guide/index.html which basically involved:

1. gu install native-image
2. Adding some options to my build.gradle:

   compileOnly "org.graalvm.nativeimage:svm"
   annotationProcessor "io.micronaut:micronaut-graal" 
   

3. Adding a native-image.properties to my resources/META-INF/native-image/example.micronaut/complete-application directory
4. Assemble the distribution, and create the GraalVM executable:

    ./gradlew assemble
   native-image --verbose --no-server -cp build/libs/vin-check-0.1-all.jar
   

5. Run the image with ./micronaut-graal-app