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From "Russell Abedin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SPARK-19776) Is the JavaKafkaWordCount example correct for Spark version 2.1?
Date Wed, 01 Mar 2017 23:30:45 GMT

    [ https://issues.apache.org/jira/browse/SPARK-19776?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15891280#comment-15891280
] 

Russell Abedin commented on SPARK-19776:
----------------------------------------

Great - thanks for the answer [~srowen] - much appreciated - I've seen the examples JAR reference
at https://github.com/apache/spark/blob/master/examples/pom.xml now.  I'll direct future questions
to the mailing list for sure.

> Is the JavaKafkaWordCount example correct for Spark version 2.1?
> ----------------------------------------------------------------
>
>                 Key: SPARK-19776
>                 URL: https://issues.apache.org/jira/browse/SPARK-19776
>             Project: Spark
>          Issue Type: Question
>          Components: Examples, ML
>    Affects Versions: 2.1.0
>            Reporter: Russell Abedin
>
> My question is https://github.com/apache/spark/blob/master/examples/src/main/java/org/apache/spark/examples/streaming/JavaKafkaWordCount.java
correct?
> I'm pretty new to both Spark and Java.  I wanted to find an example of Spark Streaming
using Java, streaming from Kafka. The JavaKafkaWordCount at https://github.com/apache/spark/blob/master/examples/src/main/java/org/apache/spark/examples/streaming/JavaKafkaWordCount.java
looked to be perfect.
> However, when I tried running it, I found a couple of issues that I needed to overcome.
> 1. This line was unnecessary:
> {code}
> StreamingExamples.setStreamingLogLevels();
> {code}
> Having this line in there (and the associated import) caused me to go looking for a dependency
spark-examples_2.10 which of no real use to me.
> 2. After running it, this line: 
> {code}
> JavaPairReceiverInputDStream<String, String> messages = KafkaUtils.createStream(jssc,
args[0], args[1], topicMap);
> {code}
> Appeared to throw an error around logging:
> {code}
> Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/spark/Logging
>         at java.lang.ClassLoader.defineClass1(Native Method)
>         at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
>         at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
>         at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
>         at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
>         at org.apache.spark.streaming.kafka.KafkaUtils$.createStream(KafkaUtils.scala:91
>         at org.apache.spark.streaming.kafka.KafkaUtils$.createStream(KafkaUtils.scala:66
>         at org.apache.spark.streaming.kafka.KafkaUtils$.createStream(KafkaUtils.scala:11
>         at org.apache.spark.streaming.kafka.KafkaUtils.createStream(KafkaUtils.scala)
>         at main.java.com.cm.JavaKafkaWordCount.main(JavaKafkaWordCount.java:72)
> {code}
> To get around this, I found that the code sample in https://spark.apache.org/docs/latest/streaming-kafka-0-10-integration.html
helped me to come up with the right lines to see streaming from Kafka in action. Specifically
this called createDirectStream instead of createStream.
> So is the example in https://github.com/apache/spark/blob/master/examples/src/main/java/org/apache/spark/examples/streaming/JavaKafkaWordCount.java
or is there something I could have done differently to get that example working?



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