Unclosed file handle (possible leak) in
Source.fromFile().mkString27 def pickInAnOrder(arr: Array[Int], criteria: Int => Boolean): Array[Int] =
28 arr.sortWith(_ < _).filter(criteria)
29
30 def readFile(path: String): String = Source.fromFile(path).mkString31
32 @Deprecated()
33 def cmpArray1(arr1: Array[Int], arr2: Array[Int]): Boolean = arr1 == arr2
Description
Calling methods such as mkString directly over scala.io.Source methods such as fromFile leaks the underneath file handle. To mitigate this, one way is to manually call the close method to free/close these resources yourself. However, the ideal and right approach is to use Scala's automatic resource management. scala.util.Using helps automatically manage either a single resource or multiple resources, thus preventing any underneath file handles from leaking.
Bad practice
val fileContents = Source.fromFile("file.txt").mkString
Recommended
// Manually closing the file yourself
val fileSource = Source.fromFile("file.txt")
val fileContents = fileSource.mkString
fileSource.close()
// Using the automatic resource management
Using(Source.fromFile("file.txt")) { reader =>
val fileContents = reader.mkString
// process the `fileContents`
}
// Handling multiple resources
Using.Manager { manage =>
val fooReader = manage(new BufferedReader(new FileReader("foo.txt")))
val barReader = manage(new BufferedReader(new FileReader("bar.txt")))
// ...
}