Throwable failure = responseProducer.getFailure();
                    requestFailed(outcome, failure);
                    String stacktrace = ExceptionUtils.getStackTrace(failure);
                    dumpThreadsUponTimeout(stacktrace);
                    System.out.printf("[%d] handling failed with exception %s%n", id, stacktrace);
                    sendFailure(httpExchange, 400, outcome);
                }