Spring Boot app takes 40 seconds to start — how to find what's slow?
asked a month ago116 viewsen
Our Spring Boot service's startup has crept up to 40s, which hurts deploys and autoscaling. How do I profile startup?
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1 Answer
1. Startup actuator endpoint: record bean initialization times:
SpringApplication app = new SpringApplication(App.class);
app.setApplicationStartup(new BufferingApplicationStartup(2048));
app.run(args);Then GET /actuator/startup lists the slowest steps.
2. Common culprits: Hibernate ddl-auto=update or validation on a big schema, classpath scanning over huge packages, eager connections to slow external services, and Flyway migrations.
3. Quick wins: - spring.main.lazy-initialization=true (test it carefully). - spring.jpa.open-in-view=false, and set ddl-auto to none in production. - Run on Java 21+ with Class Data Sharing (AppCDS). For the biggest gain, consider GraalVM native image or CRaC (checkpoint/restore).
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