Logging MDC with @Async and TaskDecorator

Question

Using Spring MVC, I have the following setup:

1. An AbstractRequestLoggingFilter derived filter for logging requests.
2. A TaskDecorator to marshal the MDC context mapping from the web request thread to the @Async thread.

I'm attempting to collect context info using MDC (or a ThreadLocal object) for all components involved in handling the request.

I can correctly retrieve the MDC context info from the @Async thread. However, if the @Async thread were to add context info to the MDC, how can I now marshal the MDC context info to the thread that handles the response?

TaskDecorator

public class MdcTaskDecorator implements TaskDecorator {
@Override
public Runnable decorate(Runnable runnable) {
    // Web thread context
    // Get the logging MDC context
    Map<String, String> contextMap = MDC.getCopyOfContextMap();

    return () -> {
        try {
            // @Async thread context
            // Restore the web thread MDC context
            if(contextMap != null) {
                MDC.setContextMap(contextMap);
            }
            else {
                MDC.clear();
            }

            // Run the new thread
            runnable.run();
        }
        finally {
            MDC.clear();
        }
    };
}

}

Async method

@Async
public CompletableFuture<String> doSomething_Async() {
    MDC.put("doSomething", "started");
    return doit();
}

Logging Filter

public class ServletLoggingFilter extends AbstractRequestLoggingFilter {
@Override
protected void beforeRequest(HttpServletRequest request, String message) {
    MDC.put("webthread", Thread.currentThread().getName()); // Will be webthread-1
}

@Override
protected void afterRequest(HttpServletRequest request, String message) {
    MDC.put("responsethread", Thread.currentThread().getName()); // Will be webthread-2
    String s = MDC.get("doSomething"); // Will be null

    // logthis();
}

}

Answer 1

I hope you have solved the problem, but if you did not, here comes a solution.
All you have to do can be summarized as following 2 simple steps:

1. Keep your class MdcTaskDecorator.
2. Extends AsyncConfigurerSupport for your main class and override getAsyncExecutor() to set decorator with your customized one as follows:

    public class AsyncTaskDecoratorApplication extends AsyncConfigurerSupport {
        @Override
        public Executor getAsyncExecutor() {
            ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
            executor.setTaskDecorator(new MdcTaskDecorator());
            executor.initialize();
            return executor;
        }

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

Answer 2

Create a bean that will pass the MDC properties from parent thread to the successor thread.

@Configuration
@Slf4j
public class AsyncMDCConfiguration {
  @Bean
  public Executor asyncExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setTaskDecorator(new MDCTaskDecorator());//MDCTaskDecorator i s a custom created  class thet implements  TaskDecorator  that is reponsible for passing on the MDC properties 
    executor.initialize();
    return executor;
  }
}


@Slf4j
public class MDCTaskDecorator implements TaskDecorator {

  @Override
  public Runnable decorate(Runnable runnable) {
    Map<String, String> contextMap = MDC.getCopyOfContextMap();
    return () -> {
      try {
        MDC.setContextMap(contextMap);
        runnable.run();
      } finally {
        MDC.clear();
      }
    };
  }
}

All Good now. Happy Coding