Compilamos la aplicación Spring Boot en nativo usando GraalVM

sdk install java 20.0.0.r8-grl

export JAVA_HOME=$HOME/.sdkman/candidates/java/current/

package com.example.reactive;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.extern.log4j.Log4j2;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.annotation.Id;
import org.springframework.data.r2dbc.core.DatabaseClient;
import org.springframework.data.repository.reactive.ReactiveCrudRepository;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.reactive.handler.SimpleUrlHandlerMapping;
import org.springframework.web.reactive.socket.WebSocketHandler;
import org.springframework.web.reactive.socket.WebSocketMessage;
import org.springframework.web.reactive.socket.server.support.WebSocketHandlerAdapter;
import reactor.core.publisher.Flux;

import java.time.Duration;
import java.time.Instant;
import java.util.Collections;
import java.util.stream.Stream;

import static org.springframework.web.reactive.function.server.RouterFunctions.route;
import static org.springframework.web.reactive.function.server.ServerResponse.ok;

@Log4j2
@SpringBootApplication(proxyBeanMethods = false)
public class ReactiveApplication {

    @Bean
    RouterFunction<ServerResponse> routes(ReservationRepository rr) {
        return route()
            .GET("/reservations", r -> ok().body(rr.findAll(), Reservation.class))
            .build();
    }

    @Bean
    ApplicationRunner runner(DatabaseClient databaseClient, ReservationRepository reservationRepository) {
        return args -> {

            Flux<Reservation> names = Flux
                .just("Andy", "Sebastien")
                .map(name -> new Reservation(null, name))
                .flatMap(reservationRepository::save);

            databaseClient
                .execute("create table reservation ( id   serial primary key, name varchar(255) not null )")
                .fetch()
                .rowsUpdated()
                .thenMany(names)
                .thenMany(reservationRepository.findAll())
                .subscribe(log::info);
        };
    }


    public static void main(String[] args) {
        SpringApplication.run(ReactiveApplication.class, args);
    }
}

interface ReservationRepository extends ReactiveCrudRepository<Reservation, Integer> {
}


@Data
@AllArgsConstructor
@NoArgsConstructor
class Reservation {

    @Id
    private Integer id;
    private String name;
}

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.M4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>reactive</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <start-class>
            com.example.reactive.ReactiveApplication
        </start-class>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.experimental</groupId>
            <artifactId>spring-graal-native</artifactId>
            <version>0.6.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-indexer</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-r2dbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>

        <dependency>
            <groupId>io.r2dbc</groupId>
            <artifactId>r2dbc-h2</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <finalName>
            ${project.artifactId}
        </finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </pluginRepository>
    </pluginRepositories>


    <profiles>
        <profile>
            <id>graal</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.graalvm.nativeimage</groupId>
                        <artifactId>native-image-maven-plugin</artifactId>
                        <version>20.0.0</version>
                        <configuration>
                            <buildArgs>
-Dspring.graal.mode=initialization-only -Dspring.graal.dump-config=/tmp/computed-reflect-config.json -Dspring.graal.verbose=true -Dspring.graal.skip-logback=true --initialize-at-run-time=org.springframework.data.r2dbc.connectionfactory.ConnectionFactoryUtils --initialize-at-build-time=io.r2dbc.spi.IsolationLevel,io.r2dbc.spi --initialize-at-build-time=io.r2dbc.spi.ConstantPool,io.r2dbc.spi.Assert,io.r2dbc.spi.ValidationDepth --initialize-at-build-time=org.springframework.data.r2dbc.connectionfactory -H:+TraceClassInitialization --no-fallback --allow-incomplete-classpath --report-unsupported-elements-at-runtime -H:+ReportExceptionStackTraces --no-server --initialize-at-build-time=org.reactivestreams.Publisher --initialize-at-build-time=com.example.reactive.ReservationRepository --initialize-at-run-time=io.netty.channel.unix.Socket --initialize-at-run-time=io.netty.channel.unix.IovArray --initialize-at-run-time=io.netty.channel.epoll.EpollEventLoop --initialize-at-run-time=io.netty.channel.unix.Errors
                            </buildArgs>
                        </configuration>
                        <executions>
                            <execution>
                                <goals>
                                    <goal>native-image</goal>
                                </goals>
                                <phase>package</phase>
                            </execution>
                        </executions>
                    </plugin>
                    <plugin>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-maven-plugin</artifactId>
                    </plugin>
                </plugins>
            </build>
        </profile>
    </profiles>

</project>

<dependency>
    <groupId>org.springframework.experimental</groupId>
    <artifactId>spring-graal-native</artifactId>
    <version>0.6.0.RELEASE</version>
</dependency>

• Compile la aplicación Java de la forma habitual
• Inicie una aplicación Java con un agente Java para recopilar información. En esta etapa, debemos asegurarnos de que la aplicación esté funcionando. Debe revisar todos los casos de uso posibles. Por cierto, este es un muy buen caso para usar CI y pruebas. Todos hablan constantemente de probar la aplicación y mejorar el rendimiento. Ahora, con GraalVM, ¡puedes hacer ambas cosas!
• Luego, reconstruya la aplicación, esta vez con el perfil de graal activo, para compilarla en la aplicación nativa, utilizando la información recopilada durante el primer lanzamiento.

mvn -DskipTests=true clean package
export MI=src/main/resources/META-INF
mkdir -p $MI 
java -agentlib:native-image-agent=config-output-dir=${MI}/native-image -jar target/reactive.jar

## it's at this point that you need to exercise the application: http://localhost:8080/reservations 
## then hit CTRL + C to stop the running application.

tree $MI
mvn -Pgraal clean package

./target/com.example.reactive.reactiveapplication

2020-04-15 23:25:08.826  INFO 7692 --- [           main] c.example.reactive.ReactiveApplication   : Started ReactiveApplication in 0.099 seconds (JVM running for 0.103)