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Avoid Using @Async Annotation in @Configuration Classes in Spring Boot

High
maintainabilityreliabilityarchitecture

What is it?​

This practice highlights the misuse of the @Async annotation within methods of a class annotated with @Configuration in Spring Boot.

Why apply it?​

Using @Async in @Configuration classes is problematic because it can lead to unexpected behavior due to the asynchronous infrastructure not being properly set up or inappropriate for a configuration context. The @Async annotation is designed for asynchronous method execution outside of a configuration class.

How to fix it?​

Remove the @Async annotation from methods within @Configuration classes. Instead, delegate asynchronous processing to appropriate service-like components.

Examples​

Example 1:​

Negative​

In this noncompliant example, a method within the @Configuration class is annotated with @Async, which is incorrect.

@EnableAsync
@Configuration
public class InvalidConfiguration {

  @Async // Noncompliant
  public void performAsyncTask() {
    // Asynchronous logic here
  }
  
  @Bean
  public MyComponent myComponent() {
    return new MyComponent();
  }
}

Example 2:​

Positive​

In this compliant example, no method within the @Configuration class uses the @Async annotation. Asynchronous processing, if needed, should be handled elsewhere.

@EnableAsync
@Configuration
public class MyConfiguration {
  
  @Bean
  public MyService myService() {
    return new MyService();
  }
  
  public void setup() {
    // Setup logic here
  }
}

Negative​

This example incorrectly places an @Async annotation on a method within a @Configuration class, which should be avoided.

@EnableAsync
@Configuration
public class WrongConfig {

  @Async // Noncompliant
  public void asyncOperation() {
    // Logic meant to be asynchronous
  }
  
  @Bean
  public SomeOtherBean someOtherBean() {
    return new SomeOtherBean();
  }
}

Example 3:​

Positive​

This example demonstrates how to properly separate asynchronous logic into a service class rather than placing it within a @Configuration class.

@EnableAsync
@Configuration
public class AppConfig {
  
  @Bean
  public TaskExecutor taskExecutor() {
    return new ThreadPoolTaskExecutor();
  }
  
  @Bean
  public AsyncService asyncService() {
    return new AsyncService();
  }
}