Ankur Mhatre
958b401f0f
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.
29 lines
1.2 KiB
Plaintext
29 lines
1.2 KiB
Plaintext
--- capacity 2048 ---
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started, recorded steps: 2048
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--- capacity 16384 ---
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started, recorded steps: 5400
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=== which steps survive truncation (capacity 2048, 5400 available) ===
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$ curl -s localhost:8080/actuator/startup | python3 -c '...'
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events: 2048
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first 3: ['spring.boot.application.starting',
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'spring.boot.application.environment-prepared',
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'spring.boot.application.context-prepared']
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last 3 : ['spring.beans.instantiate', 'spring.beans.instantiate', 'spring.beans.instantiate']
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last tags: [{'key': 'beanName', 'value': 'bulk2718'}]
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names: [('spring.beans.instantiate', 2029),
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('spring.context.bean-factory.post-process', 9),
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('spring.boot.application.starting', 1),
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('spring.boot.application.environment-prepared', 1)]
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The buffer keeps the FIRST 2048 steps and drops everything after. The timeline therefore
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ends mid-instantiation, and 'spring.context.refresh', 'spring.boot.application.started'
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and 'spring.boot.application.ready' -- the steps that bracket everything else -- are
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absent, because a step is only recorded when it ENDS.
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$ grep -ic buffer app.log
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0
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No warning. No exception. The endpoint returns 200 with a well-formed, truncated answer.
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