'Slow first call after restarting Spring Boot application

We have a React - Spring Boot application using Postgres, Hibernate, Jackson and Spring Data Rest.

After each application restart, the first call to a post route hitting one of our back-end servers is long (more than 4 seconds). Every subsequent call to the same route hitting each server is under 100 ms.

Our goal is to guarantee that none of our users is ever impacted by these slow calls after each redeployment.

We are considering triggering the calls automatically after each deployment so that the application "warms up" and our clients do not have the long calls.

Since there are several back-end servers behind a load balancer, we would like to trigger these calls directly from the back-end and not from a client.

We would like understand better what can be happening so that we to this more efficiently: could it be Hibernate? Spring lazy-loading beans? Jackson?

Hibernate L2 cache is not activated.

We expect to have the same fast response time each time (< 100 ms) instead of the initial 4s calls.

postgresqlhibernatespring-bootjackson


Solution 1:[1]

You can try to make the warm up call using an application runner.

public interface ApplicationRunner

Interface used to indicate that a bean should run when it is contained within a SpringApplication. Multiple ApplicationRunner beans can be defined within the same application context and can be ordered using the Ordered interface or @Order annotation.

e.g. 

@Component
public class AppStartupRunner implements ApplicationRunner {


  @Override
  public void run(ApplicationArguments args) throws Exception {
    System.out.println("Running");
    //Make the first call here 
  }
}

Application Runner

Solution 2:[2]

I would look at your JDBC pool. Is Spring waiting for that first request before it populates the pool? Creating database connections is an expensive operation.

If you are using a Tomcat pool, look at the initial-size and min-idle properties. For HikariCP pool, look at minimum-idle.

You should be able to observe in a test environment if JDBC connections are opened to your database before any calls are made to the application.

The built-in Spring Boot Actuator health check endpoint also has options for checking the status of the database and may help bootstrap the pool.

Solution 3:[3]

In my case, the DB connection pool was taking time for initialization on first request.

I have added minpoolsize=10 in database string, now the first request is as quick as the subsequent requests.

The default minpoolsize is 0.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 willermo
Solution 2 jlar310
Solution 3 Akshay Shinde

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