Demo 04 — Project Leyden AOT Cache

Project Leyden’s AOT cache goes beyond AppCDS — it caches parsed + linked classes AND JIT method profiles. First requests after startup get near-peak JIT performance.

How Leyden works with Spring Boot

Unlike Quarkus (which sets Leyden configuration via a single property), Spring Boot requires explicit -XX:AOTMode JVM flags in a multi-step process:

Step 1: Training run — record the AOT cache

java -XX:AOTMode=record -XX:AOTConfiguration=app.aotconf \
     -Dspring.context.exit=onRefresh \
     -jar app.jar

Step 2: Create the AOT cache

java -XX:AOTMode=create -XX:AOTConfiguration=app.aotconf \
     -XX:AOTCache=app.aot \
     -jar app.jar

Step 3: Run with the AOT cache

java -XX:AOTCache=app.aot -jar app.jar

Three-stage Containerfile

Stage	Image	Purpose
builder	`maven:3.9-eclipse-temurin-25`	Build JAR
trainer	`eclipse-temurin:25`	Training run + cache creation
runtime	`eclipse-temurin:25-jre`	Copy JAR + app.aot

JVM fingerprint must match between trainer and runtime — use the same JDK distribution.

Common pitfalls

JDK 25+ required — Leyden AOT cache is not available on JDK 21
Trainer and runtime must use the same JDK build — JVM fingerprint mismatch silently disables the cache
Use -Dspring.context.exit=onRefresh to exit cleanly after recording
The -XX:AOTMode flags are explicit — unlike Quarkus, there is no single property shortcut