运行火花时没有输出NetworkWordCount示例

我是spark的初学者,我正在尝试使用docker运行Spark示例NetworkWordCount 。 但是当我运行这个例子时没有输出:

通过docker exec -it container_id bash启动一个新的terminal,

 root@sandbox:/usr/local/spark# nc -lk 9999 a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg a ba cdefg 

然后启动另一个terminal:

 root@sandbox:/usr/local/spark# bin/run-example streaming.NetworkWordCount localhost 9999 Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties 16/05/12 02:55:57 INFO StreamingExamples: Setting log level to [WARN] for streaming example. To override add a custom log4j.properties to the classpath. 16/05/12 02:55:58 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable ... 

任何人都可以帮助我?