Inner block local variables without returning any reference are not freed !

memreftest.scala

#!/bin/sh
exec scala -deprecation -nocompdaemon "$0" "$@"
!#

def sleep(inSeconds:Int) = Thread.sleep(inSeconds*1000L)

def usedMemoryInMo_sillyimpl() = {
  System.gc
  sleep(2)
  val rt= java.lang.Runtime.getRuntime
  (rt.totalMemory - rt.freeMemory)/1024/1024
}

def printmem(msg:String) { println(s"$msg : ${usedMemoryInMo_sillyimpl()}Mb") }

def allocate(szInMb:Int=24) = Array.fill[Byte](1024*1024*szInMb)(util.Random.nextInt(256).toByte)

sleep(5)
printmem("1")
printmem("2")

println("Allocation done within an internal block :")

{
  printmem("2-1")

  {
    printmem("2-1-1")
    val innerAllocated = allocate()
    printmem("2-1-2")
    sleep(10)
    printmem("2-1-3")
  }
  printmem("2-2")
}
printmem("3")
printmem("4")

println("Now with an allocation done within a function :")

def processing() {
  val xx = allocate()
}

{
  printmem("4-1")

  {
    printmem("4-1-1")
    processing()
    printmem("4-1-2")
    sleep(10)
    printmem("4-1-3")
  }
  printmem("4-2")
}
printmem("5")
printmem("6")