revisted...

memreftest2.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("before testit")

def testit = {
  printmem("testit start")

  {
    printmem("2-1-1")
    //val innerAllocated = allocate()
    allocate() match {
      case x => // do the processing...
    }
    // NOT FREEABLE !
    printmem("2-1-2")
    sleep(10)
    printmem("2-1-3")
    "done"
  }
  // NOT FREEABLE !
  printmem("testit outside inner block")
  println("ready for a heap dump, waiting 100s")
  sleep(100)
  printmem("testit end")
}

testit
// FREEABLE  NOW

printmem("aftertestit")
printmem("4")