docs: private RemotingCommand doBizWithReqLimit(Channel channel, RemotingCommand request) throws RemotingCommandException {
  
          if (rateLimiter.tryAcquire(reqLimitAcquireTimeout, TimeUnit.MILLISECONDS)) {
              return doBiz(channel, request);
          }
          return RemotingCommand.createResponseCommand(RemotingProtos.ResponseCode.SYSTEM_BUSY.code(), "remoting server is busy!");
      }