spring boot cold start taking too long on aws lambda and boot initializes twice

Question

this is strange but my spring boot api taking much longer that expected when deployed on aws lambda. in the cloudwatch log, i see spring boot is starting up twice first with default profile and second with a profile i set. Why should it boot twice.. that is significantly costing time.. Source Code: lambdahandler.java

public class LambdaHandler implements RequestStreamHandler {

    private static SpringBootLambdaContainerHandler<AwsProxyRequest, AwsProxyResponse> handler;

    static {
        try {
            handler = SpringBootLambdaContainerHandler.getAwsProxyHandler(Application.class);
            handler.activateSpringProfiles("lambda");
        } catch (ContainerInitializationException e) {
            // Re-throw the exception to force another cold start
            e.printStackTrace();
            throw new RuntimeException("Could not initialize Spring Boot application", e);
        }
    }

application.java

@SpringBootApplication
    public class Application extends SpringBootServletInitializer {
        public static void main(String[] args) {
            SpringApplication.run(Application.class, args);
        }

both these files are in the same package

config.java

@Configuration
@EnableWebMvc
@Profile("lambda")
public class Config {

    /**
     * Create required HandlerMapping, to avoid several default HandlerMapping instances being created
     */
    @Bean
    public HandlerMapping handlerMapping() {
        return new RequestMappingHandlerMapping();
    }

    /**
     * Create required HandlerAdapter, to avoid several default HandlerAdapter instances being created
     */
    @Bean
    public HandlerAdapter handlerAdapter() {
        return new RequestMappingHandlerAdapter();
    }
..
..

}

pom.xml

<dependency>
      <groupId>com.amazonaws.serverless</groupId>
      <artifactId>aws-serverless-java-container-spring</artifactId>
      <version>[0.1,)</version>
    </dependency>
<dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-lambda-java-core</artifactId>
      <version>1.2.1</version>
    </dependency>
    <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-lambda-java-events</artifactId>
      <version>3.1.0</version>
    </dependency>

cloudwatch log

    07:16:51.546 [main] INFO com.amazonaws.serverless.proxy.internal.LambdaContainerHandler - Starting Lambda Container Handler
:: Spring Boot ::                        
    2020-09-05 07:16:52.724  INFO 1 --- [           main] lambdainternal.LambdaRTEntry             : Starting LambdaRTEntry on 169.254.184.173 with PID 1 (/var/runtime/lib/LambdaJavaRTEntry-1.0.jar started by sbx_user1051 in /)
    2020-09-05 07:16:52.726  INFO 1 --- [           main] lambdainternal.LambdaRTEntry             : No active profile set, falling back to default profiles: default
    2020-09-05 07:16:52.906  INFO 1 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@1e81f4dc: startup date [Sat Sep 05 07:16:52 UTC 2020]; root of context hierarchy
    
    ..
    ..
    2020-09-05 07:16:57.222  INFO 1 --- [           main] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 40 ms
    :: Spring Boot ::                        
    2020-09-05 07:16:57.442  INFO 1 --- [           main] lambdainternal.LambdaRTEntry             : Starting LambdaRTEntry on 169.254.184.173 with PID 1 (/var/runtime/lib/LambdaJavaRTEntry-1.0.jar started by sbx_user1051 in /)
    2020-09-05 07:16:57.442  INFO 1 --- [           main] lambdainternal.LambdaRTEntry             : The following profiles are active: lambda
    2020-09-05 07:16:57.445  INFO 1 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5ef60048: startup date [Sat Sep 05 07:16:57 UTC 2020]; root of context hierarchy

Answer 1

Why should it boot twice ?

I suspect your code change with activateSpringProfiles force reinitialisation.

handler.activateSpringProfiles("lambda");

https://github.com/awslabs/aws-serverless-java-container/blob/master/aws-serverless-java-container-spring/src/main/java/com/amazonaws/serverless/proxy/spring/SpringBootLambdaContainerHandler.java#L149

Try setting active profile with env variable SPRING_PROFILES_ACTIVE as part of lambda configuration file.

Java and serverless

If you use java for serverless application like AWS lambdas I would recommend for looking a framework which supports Ahead-of-Time compilation which will boost a lot your application start.

For instance have a look at Micronaut, Quarkus using with Graalvm. Spring Boot is not the best option using with directly with AWS lambdas.