How Can I Maintain Request Scope in Asynchronous Tasks?

Maintaining Request Scope in Async Tasks

In web applications, it is common to execute asynchronous tasks after receiving a request. However, ensuring that these tasks have access to request-specific objects, such as those annotated with @Scope(value = WebApplicationContext.SCOPE_REQUEST), can be challenging.

When processing requests in a non-blocking manner, the default SimpleAsyncTaskExecutor does not have access to the request thread's scope, leading to exceptions like "Scope 'request' is not active for the current thread."

To address this issue, a custom ContextAwarePoolExecutor can be created. This executor stores request context information with tasks and leverages a ContextAwareCallable to set and clear the necessary context for the background thread.

Custom Executor Implementation:

<code class="java">public class ContextAwarePoolExecutor extends ThreadPoolTaskExecutor {
    @Override
    public <T> Future<T> submit(Callable<T> task) {
        return super.submit(new ContextAwareCallable(task, RequestContextHolder.currentRequestAttributes()));
    }
}</code>

Context-Aware Callable:

<code class="java">public class ContextAwareCallable<T> implements Callable<T> {
    private Callable<T> task;
    private RequestAttributes context;

    public ContextAwareCallable(Callable<T> task, RequestAttributes context) {
        this.task = task;
        this.context = context;
    }

    @Override
    public T call() throws Exception {
        if (context != null) {
            RequestContextHolder.setRequestAttributes(context);
        }
        try {
            return task.call();
        } finally {
            RequestContextHolder.resetRequestAttributes();
        }
    }
}</code>

Configuration Override:

<code class="java">@Configuration
public class ExecutorConfig extends AsyncConfigurerSupport {
    @Override
    @Bean
    public Executor getAsyncExecutor() {
        return new ContextAwarePoolExecutor();
    }
}</code>

By utilizing this custom executor, asynchronous tasks can seamlessly access request-scoped objects, overcoming the limitations of the default SimpleAsyncTaskExecutor.

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