protected int getResponseSetSize() {
    int responseSetSize = 0;
    if (asyncResponseHandler != null) {
      responseSetSize = asyncResponseHandler.getResponseSetSize();
    }
    return responseSetSize;
  }
Gets total number of responses being (or waiting to be) sent.
@return total size of response map/set.
ambry-rest/src/main/java/com/github/ambry/rest/AsyncRequestResponseHandler.java