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.
57 lines
2.9 KiB
Plaintext
57 lines
2.9 KiB
Plaintext
=== Where getApplicationStartup() actually lives (Spring Framework 7.0.9) ===
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Injecting ApplicationContext and calling getApplicationStartup() does not compile:
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[ERROR] .../config/StartupBeans.java:[22,45] cannot find symbol
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symbol: method getApplicationStartup()
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location: variable context of type org.springframework.context.ApplicationContext
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javap says the accessor is declared one interface down, and also on the bean factory:
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$ javap -cp . org.springframework.context.ConfigurableApplicationContext | grep ApplicationStartup
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public abstract void setApplicationStartup(org.springframework.core.metrics.ApplicationStartup);
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public abstract org.springframework.core.metrics.ApplicationStartup getApplicationStartup();
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$ javap -cp . org.springframework.beans.factory.config.ConfigurableBeanFactory | grep ApplicationStartup
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public abstract void setApplicationStartup(org.springframework.core.metrics.ApplicationStartup);
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public abstract org.springframework.core.metrics.ApplicationStartup getApplicationStartup();
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=== The buffering API surface (spring-boot 4.1.1) ===
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$ javap -cp . org.springframework.boot.context.metrics.buffering.BufferingApplicationStartup
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public class BufferingApplicationStartup implements org.springframework.core.metrics.ApplicationStartup {
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public BufferingApplicationStartup(int);
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public void startRecording();
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public void addFilter(java.util.function.Predicate<org.springframework.core.metrics.StartupStep>);
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public org.springframework.core.metrics.StartupStep start(java.lang.String);
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public StartupTimeline getBufferedTimeline();
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public StartupTimeline drainBufferedTimeline();
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}
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$ javap -cp . org.springframework.boot.context.metrics.buffering.StartupTimeline$TimelineEvent
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public class StartupTimeline$TimelineEvent {
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public java.time.Instant getStartTime();
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public java.time.Instant getEndTime();
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public java.time.Duration getDuration();
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public org.springframework.core.metrics.StartupStep getStartupStep();
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}
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Note: there is no setter for the buffer size and no Spring property that installs this.
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The only constructor takes the capacity, and it must be handed to SpringApplication
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before run().
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=== You do not need a @Bean method for it ===
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Declaring one produces a startup failure, because Boot has already registered the
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instance as a singleton:
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Parameter 0 of constructor in com.ankurm.startup.web.StartupDiagnosticsEndpoint
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required a single bean, but 2 were found:
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- bufferingApplicationStartup: defined by method 'bufferingApplicationStartup'
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in class path resource [com/ankurm/startup/config/StartupBeans.class]
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- applicationStartup: a programmatically registered singleton
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So the correct move is to inject ApplicationStartup directly and narrow with instanceof.
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Injecting BufferingApplicationStartup by its concrete type compiles and works -- until
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somebody runs without tracking, at which point the application will not start at all.
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