protected boolean isAlive() {
    if (_messageDispatcher == null) {
      return false;
    }
    return !_messageDispatcher.isStopped();
  }
Returns whether the proxy is alive. It is alive if its message dispatcher is processing
messages.

@return whether the proxy is alive
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/CacheClientProxy.java