Advanced Asynchronous Execution and Performance Tuning in Spring Boot

The article, written by a senior architect, introduces several ways to perform asynchronous execution in Spring Boot, including the @Async annotation with @EnableAsync, CompletableFuture, supplyAsync, runAsync, WebAsyncTask, DeferredResult, and DeferredResult with timeout handling.

It provides complete Java code examples for each method, demonstrating thread creation, future handling, and controller implementations.

Key code snippets:

@Async
@EnableAsync
public class AsyncConfig { ... }

CompletableFuture<Integer> future = new CompletableFuture<>();
new Thread(new AskThread(future)).start();
future.complete(60);
System.out.println(future.get());

@RestController
public class HelloController {
    @GetMapping("/helloworld")
    public String helloWorldController() {
        return hello.sayHello();
    }
}

Additional performance optimizations are discussed, such as increasing Tomcat's maximum connections and threads via a custom TomcatConnectorCustomizer, switching the embedded server from Tomcat to Undertow, using @ComponentScan for faster package scanning, and employing BufferedWriter for I/O buffering.

@Configuration
public class TomcatConfig {
    @Bean
    public ConfigurableServletWebServerFactory webServerFactory() {
        TomcatServletWebServerFactory tomcatFactory = new TomcatServletWebServerFactory();
        tomcatFactory.addConnectorCustomizers(new MyTomcatConnectorCustomizer());
        return tomcatFactory;
    }
}

class MyTomcatConnectorCustomizer implements TomcatConnectorCustomizer {
    public void customize(Connector connector) {
        Http11NioProtocol protocol = (Http11NioProtocol) connector.getProtocolHandler();
        protocol.setMaxConnections(20000);
        protocol.setMaxThreads(2000);
    }
}

The article also shows how to intercept asynchronous requests with AsyncHandlerInterceptor and outlines configuration classes for customizing the servlet container.

References and further reading links are included at the end of the article.