scala - spark jupyter notebook 不显示 scala 控制台输出

Question

1）我正在学习流式传输并遇到控制台（scala）上没有显示（通过sendEVent的println）的问题。我进一步尝试植入 println("xyz") 行，发现只有当它们没有嵌入到“while”块的块中时才会被打印出来……否则即使放在 while 循环之前也不会被打印。我又放了几行这些 println("xyz") ，发现有些可能会被挡住……只有最后一行被打印出来。

以前我在 Storm 流媒体上也遇到过两次不同的代码：Jupyter Notebook 没有打印出任何东西，但在 Scala Shell 上完全没问题。

2）我也想知道那些awaitTermination()，比如：messages.writeStream.outputMode("append").format("console").option("truncate", false).start().awaitTermination() (我也没有从控制台获得输出）

或那些“不定式循环”，如下所示： var finished = false while (!finished) {................. ..}

他们是否在等待像停止或 [CTR]C 之类的硬中断......或者如何正确地打破它们？所以下一行被执行。我很困惑，因为编写示例/教程的作者对此一无所知。

enter code here

import java.util._
import scala.collection.JavaConverters._
import java.util.concurrent._

import org.apache.spark._
import org.apache.spark.streaming._
import org.apache.spark.eventhubs.ConnectionStringBuilder

// Event hub configurations
// Replace values below with yours        
val eventHubName = "<Event hub name>"
val eventHubNSConnStr = "<Event hub namespace connection string>"
val connStr = ConnectionStringBuilder (eventHubNSConnStr)
.setEventHubName(eventHubName).build 

import com.microsoft.azure.eventhubs._
val pool = Executors.newFixedThreadPool(1)
val eventHubClient = EventHubClient.create(connStr.toString(), pool)

def sendEvent(message: String) = {
  val messageData = EventData.create(message.getBytes("UTF-8"))
  eventHubClient.get().send(messageData)
  println("Sent event: " + message + "\n")
}


import twitter4j._
import twitter4j.TwitterFactory
import twitter4j.Twitter
import twitter4j.conf.ConfigurationBuilder

// Twitter application configurations
// Replace values below with yours   
val twitterConsumerKey = "<CONSUMER KEY>"
val twitterConsumerSecret = "<CONSUMER SECRET>"
val twitterOauthAccessToken = "<ACCESS TOKEN>"
val twitterOauthTokenSecret = "<TOKEN SECRET>"

val cb = new ConfigurationBuilder()
cb.setDebugEnabled
(true).setOAuthConsumerKeywitterConsumerKey).setOAuthConsumerSecret
(twitterConsumerSecret).setOAuthAccessToken
(twitterOauthAccessToken).setOAuthAccessTokenSecret(twitterOauthTokenSecret)

val twitterFactory = new TwitterFactory(cb.build())
val twitter = twitterFactory.getInstance()

//Getting tweets with keyword "Azure" and sending them to Event Hub realtime 

val query = new Query(" #Azure ")
query.setCount(100)
query.lang("en")
var finished = false
while (!finished) {
  val result = twitter.search(query)
  val statuses = result.getTweets()
  var lowestStatusId = Long.MaxValue
  for (status <- statuses.asScala) {
  if(!status.isRetweet()){
  sendEvent(status.getText())
}
  lowestStatusId = Math.min(status.getId(), lowestStatusId)
  Thread.sleep(2000)
}
query.setMaxId(lowestStatusId - 1)
}

// Closing connection to the Event Hub
eventHubClient.get().close()

标签： scalaapache-sparkspark-streaming