* @param nThreads the number of threads in the pool
     * @return a new ThreadPoolExecutor configured for this callback
     */
    protected ExecutorService newFixedThreadPool(final int nThreads) {
        if (logger.isDebugEnabled()) {
            logger.debug("Initialized executor thread pool: size={}", nThreads);
        }
        return new ThreadPoolExecutor(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(nThreads),