private AsyncRequestWorker getWorker() {
    long startTime = System.currentTimeMillis();
    int index = ThreadLocalRandom.current().nextInt(requestWorkersCount);
    logger.trace("Request worker thread at randomly generated index {} is used", index);
    AsyncRequestWorker worker = asyncRequestWorkers.get(index);
    metrics.requestWorkerSelectionTimeInMs.update(System.currentTimeMillis() - startTime);
    return worker;
  }
Returns a {@link AsyncRequestWorker} that can be used to handle requests.
@return a {@link AsyncRequestResponseHandler} that can be used to handle requests.
ambry-rest/src/main/java/com/github/ambry/rest/AsyncRequestResponseHandler.java