// the defined parallism, while making sure the pool will not
            // be exhausted
            //
            return new ThreadPoolExecutor(
                    parallelism, Integer.MAX_VALUE, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>()) {
                final AtomicInteger parked = new AtomicInteger();

                @Override

                if (fieldName.endsWith("]")) {
                    key = fieldName.substring(fieldName.lastIndexOf('[') + 1, fieldName.length() - 1);
                    try {
                        key = Integer.valueOf(key.toString());
                    } catch (NumberFormatException e) {
                        // use key as is
                    }
                }