Update RecoverableNetworkWordCount.scala

Trying this example, I missed the moment when the checkpoint was iniciated

Author: comcmipi <pitonak@fns.uniba.sk>

Closes #2735 from comcmipi/patch-1 and squashes the following commits:

b6d8001 [comcmipi] Update RecoverableNetworkWordCount.scala
96fe274 [comcmipi] Update RecoverableNetworkWordCount.scala

examples/src/main/scala/org/apache/spark/examples/streaming/RecoverableNetworkWordCount.scala

@@ -56,7 +56,7 @@ import org.apache.spark.util.IntParam
  */
 object RecoverableNetworkWordCount {
 
-  def createContext(ip: String, port: Int, outputPath: String) = {
+  def createContext(ip: String, port: Int, outputPath: String, checkpointDirectory: String) = {
 
     // If you do not see this printed, that means the StreamingContext has been loaded
     // from the new checkpoint
@@ -66,6 +66,7 @@ object RecoverableNetworkWordCount {
     val sparkConf = new SparkConf().setAppName("RecoverableNetworkWordCount")
     // Create the context with a 1 second batch size
     val ssc = new StreamingContext(sparkConf, Seconds(1))
+    ssc.checkpoint(checkpointDirectory)
 
     // Create a socket stream on target ip:port and count the
     // words in input stream of \n delimited text (eg. generated by 'nc')
@@ -101,7 +102,7 @@ object RecoverableNetworkWordCount {
     val Array(ip, IntParam(port), checkpointDirectory, outputPath) = args
     val ssc = StreamingContext.getOrCreate(checkpointDirectory,
       () => {
-        createContext(ip, port, outputPath)
+        createContext(ip, port, outputPath, checkpointDirectory)
       })
     ssc.start()
     ssc.awaitTermination()