HTTP 408 Request Timeout in JHipster Spring MVC: Intercepting Container‑Generated Timeouts

Intercepting Container-Level 408 Timeouts

In a standard JHipster Spring MVC architecture, it is not possible to intercept an HTTP 408 Request Timeout using @ControllerAdvice or a Servlet Filter if the timeout is triggered by the servlet container (e.g., Tomcat) via server.connection-timeout.

This is because the container generates the 408 response at the connector level. The connection is terminated before the request is ever dispatched to the DispatcherServlet, meaning the Spring context—and by extension, your global exception handlers—is never invoked for that request cycle.

Implementing Per-Endpoint Timeouts

To achieve graceful handling and logging of timeouts, you must shift the timeout responsibility from the container to the application layer. The recommended pattern in Spring MVC is using Asynchronous Request Processing.

Implementation Steps

1. Use DeferredResult: Change the controller return type from a POJO/ResponseEntity to DeferredResult<T>.
2. Configure Timeout Value: Set the timeout on the DeferredResult instance.
3. Handle the Timeout: Use the onTimeout callback to throw a specific exception or return a custom error object.

@GetMapping("/long-process")
public DeferredResult<ResponseEntity<String>> handleLongProcess() {
    DeferredResult<ResponseEntity<String>> output = new DeferredResult<>(5000L);
    
    output.onTimeout(() -> {
        // This allows @ControllerAdvice to catch the resulting exception
        throw new ResponseStatusException(HttpStatus.REQUEST_TIMEOUT, "Endpoint timeout exceeded");
    });

    // Process logic asynchronously
    return output;
}

Analysis of Alternative Approaches

Approach	Effectiveness	Trade-off
Custom Annotation + Aspect	Moderate	Requires an underlying async mechanism (like CompletableFuture) to actually enforce the clock; otherwise, it is just metadata.
Spring WebFlux	High	Requires a full migration from Spring MVC to a reactive stack to use .timeout() operators.
Servlet Filter	Low	Cannot catch 408s generated by the container's connector.

Verification

To verify this behavior, set server.connection-timeout=100ms in your properties. Attempt a slow request; you will observe the 408 response in the browser without any corresponding logs in your @ControllerAdvice. Transitioning the endpoint to DeferredResult will allow the application to regain control.

Diagnostic Requirement: Please specify if these timeouts are occurring during the initial request upload (connection phase) or during long-running server processing, as the latter can be solved with the async patterns described above.