protected int getQueueSize() {
    return _messageQueue == null ? 0 : _messageQueue.size();
  }
Returns the size of the queue for heuristic purposes. This size may be changing concurrently
if puts / gets are occurring at the same time.

@return the size of the queue
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/MessageDispatcher.java