foreach - Scala Parallel Print Hanging the console -

i new scala world , trying exercises book. so, have example print vector in sequential , parallel fashion. former works , later hangs console.

code

val v = vector.range(0, 10) v.foreach(println)

code output

0123456789

but if use same code, instead of using foearch, use par, freezes console

val v = vector.range(0,10) v.par.foreach(println)

the book using says output should like:

5678901234

but hangs , program never finishes.

can explain me why?

WIKI