Spark Job Stuck and Never Finish Executing - scala

Question

I am trying to do some analysis on a dataset using spark. I am using sbt scala 2.12.8 on my local machine which is (16 GB).
The issue is that Spark Job never finished executing after using transformation and then an action, if I use transformation only or action only it would be executed within seconds.
Code:
package wikipedia
import org.apache.spark.SparkConf
import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import scala.io.Source
import org.apache.spark.rdd.RDD
case class WikipediaArticle2(title: String, text: String) {
/**
* #return Whether the text of this article mentions `lang` or not
* #param lang Language to look for (e.g. "Scala")
*/
def mentionsLanguage(lang: String): Boolean = text.split(' ').contains(lang)
}
object WikipediaData2 {
def lines: List[String] = {
Option(getClass.getResourceAsStream("/wikipedia/wikipedia.dat")) match {
case None => sys.error("Please download the dataset as explained in the assignment instructions")
case Some(resource) => Source.fromInputStream(resource).getLines().toList
}
}
def parse(line: String): WikipediaArticle2 = {
val subs = "</title><text>"
val i = line.indexOf(subs)
val title = line.substring(14, i)
val text = line.substring(i + subs.length, line.length-16)
WikipediaArticle2(title, text)
}
}
object WikipediaTest {
val langs = List(
"JavaScript", "Java", "PHP", "Python", "C#", "C++", "Ruby", "CSS",
"Objective-C", "Perl", "Scala", "Haskell", "MATLAB", "Clojure", "Groovy")
val conf: SparkConf = new SparkConf()
.setMaster("local[*]") // tried local[4] 4 cores
.setAppName("Wikis Most Popular Languages")
val sc: SparkContext = new SparkContext(conf)
sc.setLogLevel("ERROR")
// Hint: use a combination of `sc.parallelize`, `WikipediaData.lines` and `WikipediaData.parse`
// val wikiRdd: RDD[WikipediaArticle] = sc.parallelize(WikipediaData.lines.map(WikipediaData.parse)).cache()
val wikiRdd: RDD[WikipediaArticle2] = sc.parallelize(WikipediaData2.lines).map(WikipediaData2.parse)
def main(args: Array[String]): Unit = {
// wikiRdd.count() // returned 4086
// wikiRdd.take(2) // result within less than second
// wikiRdd.filter(a => a.mentionsLanguage("Java")).take(2) // execution stuck here
// wikiRdd.filter(a => a.mentionsLanguage("Perl")).collect() // exceution stuck here
sc.stop()
}
}
on terminal I execute the code like this:
$ sbt
$ console
scala> import wikipedia.WikipediaTest._
scala> wikiRdd.count() // returned 4086
scala> wikiRdd.take(2) // result within less than second
scala> wikiRdd.filter(a => a.mentionsLanguage("Java")).take(2)
This code snippet also get the Job to freeze:
wikiRdd.filter(a => a.mentionsLanguage("Perl")).collect()
Spark Job UI
I have been stumbled for hours and I have no idea what's wrong.
Any suggestion folks?