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.
45 lines
1.5 KiB
Markdown
45 lines
1.5 KiB
Markdown
# Post metadata
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**Title**
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Why Your Spring Boot App Takes 8 Seconds to Start: A Bean-by-Bean Diagnosis
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**Slug**
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`spring-boot-startup-time-bean-by-bean-diagnosis`
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**Excerpt**
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Spring Boot logs one startup number and hides four phases behind it. This walks through
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turning on the `ApplicationStartup` instrumentation that ships switched off, reading the
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step tree by self time rather than total duration — the mistake that makes people optimise
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a bean costing 10 ms instead of the one costing 504 — and then puts measured numbers on
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component scanning (0.11 ms per class inspected, whether or not it is a bean), on the
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silent truncation a 2048-step buffer performs on your recording, and on the JDK 25 AOT
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cache, which took 6.93 s to 4.82 s on the companion project without a line of application
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code changing.
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**Categories**
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Java (328), Spring (355)
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**Yoast**
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- `_yoast_wpseo_title`: Spring Boot Startup Time: A Bean-by-Bean Diagnosis
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- `_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.
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- `_yoast_wpseo_focuskw`: spring boot startup time
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**Companion repository**
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`asmhatre/spring-boot-demo` → [`spring-boot-startup-time/`](../)
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**Jira**
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BLOG-618
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**Verified against**
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Spring Boot 4.1.1 (GA 20 August 2026), Spring Framework 7.0.9, Spring Data JPA 4.1.1,
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Hibernate ORM 7.4.5.Final, Tomcat 11.0.24, Micrometer 1.17.1, H2 2.4.240,
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Temurin 25.0.4.1+1 LTS, Maven 3.9.11.
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