Scala vs F# on List range from 1 to 100000000

Question

I have written a list manipulation function both on F# and Scala to compare the performance. To test that function I need to initialize a List from 1 to 100000000.

F#:

let l = [1..100000000];;

Real: 00:00:32.954, CPU: 00:00:34.593, GC gen0: 1030, gen1: 520, gen2: 9

This works.

Scala: Scala -J-Xmx2G option

val l = (1 to 10000000).toList // works

val l = (1 to 100000000).toList // no response long while and finally got java.lang.OutOfMemoryError: Java heap space

With 100000000 (100,000,000), no response for a long while (an hour) with 75% to 90% CPU utilization and 2GB memory utilization and finally got java.lang.OutOfMemoryError: Java heap space.

Am I doing anything wrong in Scala?

Answer 1

Note that val l = (1 to 100000000).toList creates a new List with contents from the original Range (1 to 100000000), hence a chance for a shortage in the heap space, as well as heavy triggering of the garbage collector. Increase -J-Xmx as @krynio suggested.

Yet without modifying the heap size, consider the use of iterators, especially if the performance test relies on a sequential iteration over the list; like this

(1 to 100000000).iterator
res0: Iterator[Int] = non-empty iterator