asmhatre
29676e0cc8
Adds spring-boot-startup-time/, the companion project for BLOG-618: a runnable Spring Boot 4.1.1 application on JDK 25 that installs BufferingApplicationStartup and FlightRecorderApplicationStartup behind a system property, and a /diag/startup endpoint that computes step self time -- the number /actuator/startup does not give you and the one that names the actual culprits. Captured under docs/output/: the step tree sorted both ways, the same startup as JFR events, a +5000-class experiment putting 0.11 ms per scanned class on the classpath scan tax, the silent truncation a 2048-step buffer performs, and JDK 25 AOT cache timings (6.93 s to 4.82 s). Post body and metadata live in post/. Moves the existing Actuator project into actuator-in-production/ so the repository holds one directory per article; the root README is now an index.
1.5 KiB
Post metadata
Title
Why Your Spring Boot App Takes 8 Seconds to Start: A Bean-by-Bean Diagnosis
Slug
spring-boot-startup-time-bean-by-bean-diagnosis
Excerpt
Spring Boot logs one startup number and hides four phases behind it. This walks through
turning on the ApplicationStartup instrumentation that ships switched off, reading the
step tree by self time rather than total duration — the mistake that makes people optimise
a bean costing 10 ms instead of the one costing 504 — and then puts measured numbers on
component scanning (0.11 ms per class inspected, whether or not it is a bean), on the
silent truncation a 2048-step buffer performs on your recording, and on the JDK 25 AOT
cache, which took 6.93 s to 4.82 s on the companion project without a line of application
code changing.
Categories
Java (328), Spring (355)
Yoast
_yoast_wpseo_title: Spring Boot Startup Time: A Bean-by-Bean Diagnosis_yoast_wpseo_metadesc: Turn on Spring Boot's built-in startup instrumentation, read the step tree by self time, and see measured numbers for component scanning, buffer truncation and the JDK 25 AOT cache._yoast_wpseo_focuskw: spring boot startup time
Companion repository
asmhatre/spring-boot-demo → spring-boot-startup-time/
Jira
BLOG-618
Verified against
Spring Boot 4.1.1 (GA 20 August 2026), Spring Framework 7.0.9, Spring Data JPA 4.1.1, Hibernate ORM 7.4.5.Final, Tomcat 11.0.24, Micrometer 1.17.1, H2 2.4.240, Temurin 25.0.4.1+1 LTS, Maven 3.9.11.