星火与Twitter流 - 没有输出流中注册,所以没有执行 [英] Spark Streaming with Twitter - No output streams registered, so nothing to execute
问题描述
我试图执行使用Twitter火花流的例子。这是我的code
公共静态无效的主要(字符串..参数){
SparkConf的conf =新SparkConf()setAppName(Spark_Streaming_Twitter)setMaster(本地)。
JavaSparkContext SC =新JavaSparkContext(CONF);
JavaStreamingContext JSSC =新JavaStreamingContext(SC,新的持续时间(2));
JavaSQLContext sqlCtx =新JavaSQLContext(SC);
的String [] =过滤器新的String [] {足球}; JavaReceiverInputDStream<状态> receiverStream = TwitterUtils.createStream(JSSC,过滤器); jssc.start();
jssc.awaitTermination();}
但我发现了以下异常
异常线程mainjava.lang.AssertionError:断言失败:注册无输出流,因此没有执行
。在斯卡拉preDEF $ .assert(predef.scala:179)
在org.apache.spark.streaming.DStreamGraph.validate(DStreamGraph.scala:158)
在org.apache.spark.streaming.StreamingContext.validate(StreamingContext.scala:416)
在org.apache.spark.streaming.StreamingContext.start(StreamingContext.scala:437)
在org.apache.spark.streaming.api.java.JavaStreamingContext.start(JavaStreamingContext.scala:501)
在org.learning.spark.TwitterStreamSpark.main(TwitterStreamSpark.java:53)
任何建议如何解决这个问题?
当输出操作者被调用时,它触发的计算
流。
块引用>而对DSTREAM输出操作符不计算被调用。基本上你需要调用任何下面的方法对数据流上
打印()
foreachRDD(FUNC)
saveAsObjectFiles(preFIX,[后缀])
saveAsTextFiles(preFIX,[后缀])
saveAsHadoopFiles(preFIX,[后缀])<一个href=\"http://spark.apache.org/docs/latest/streaming-programming-guide.html#output-operations\">http://spark.apache.org/docs/latest/streaming-programming-guide.html#output-operations
如果需要,您也可以先申请任何变换,然后输出功能了。
I'm trying to execute a spark streaming example using Twitter. This is my code
public static void main (String.. args) { SparkConf conf = new SparkConf().setAppName("Spark_Streaming_Twitter").setMaster("local"); JavaSparkContext sc = new JavaSparkContext(conf); JavaStreamingContext jssc = new JavaStreamingContext(sc, new Duration(2)); JavaSQLContext sqlCtx = new JavaSQLContext(sc); String[] filters = new String[] {"soccer"}; JavaReceiverInputDStream<Status> receiverStream = TwitterUtils.createStream(jssc,filters); jssc.start(); jssc.awaitTermination(); }
But I'm getting the following exception
Exception in thread "main" java.lang.AssertionError: assertion failed: No output streams registered, so nothing to execute at scala.Predef$.assert(Predef.scala:179) at org.apache.spark.streaming.DStreamGraph.validate(DStreamGraph.scala:158) at org.apache.spark.streaming.StreamingContext.validate(StreamingContext.scala:416) at org.apache.spark.streaming.StreamingContext.start(StreamingContext.scala:437) at org.apache.spark.streaming.api.java.JavaStreamingContext.start(JavaStreamingContext.scala:501) at org.learning.spark.TwitterStreamSpark.main(TwitterStreamSpark.java:53)
Any suggestion how to fix this issue?
解决方案When an output operator is called, it triggers the computation of a stream.
Without output operator on DStream no computation is invoked. basically you will need to invoke any of below method on stream
print() foreachRDD(func) saveAsObjectFiles(prefix, [suffix]) saveAsTextFiles(prefix, [suffix]) saveAsHadoopFiles(prefix, [suffix])
http://spark.apache.org/docs/latest/streaming-programming-guide.html#output-operations
you can also first apply any transformations and then output functions too if required.
这篇关于星火与Twitter流 - 没有输出流中注册,所以没有执行的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!