Spring Boot Tutorial 0/110 lessons ~6 min read Lesson 55“Production-grade backends”

Async Processing

Some work shouldn't block the request: sending emails, generating thumbnails, calling slow third parties.

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Focus

3 guided sections

Practice signal

Examples included

Career prep

Foundation builder

Introduction

Some work shouldn't block the request: sending emails, generating thumbnails, calling slow third parties. @Async off-loads to a thread pool; for heavy workloads graduate to message queues.

Informative example

@Configuration @EnableAsync
public class AsyncConfig {
  @Bean(name = "taskExecutor")
  public ThreadPoolTaskExecutor exec() {
    var ex = new ThreadPoolTaskExecutor();
    ex.setCorePoolSize(8);
    ex.setMaxPoolSize(32);
    ex.setQueueCapacity(500);
    ex.setThreadNamePrefix("acme-async-");
    ex.initialize();
    return ex;
  }
}

@Service
public class AuditService {
  @Async
  public CompletableFuture<Void> record(AuditEvent e) {
    audits.save(e);
    return CompletableFuture.completedFuture(null);
  }
}

Best practices

Configure your own executor; the default unbounded pool is dangerous.
@Async only works across Spring proxies — same-class calls don't async.
For reliability, use a queue (Kafka, RabbitMQ, SQS), not in-process async.

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