Tim's long adder test with streams but groovier :-)

LongAdderTest.groovy

import java.util.Random
import java.util.concurrent.ConcurrentHashMap
import java.util.concurrent.atomic.LongAdder
import java.util.stream.IntStream

def frequencyMap = new ConcurrentHashMap<>()
def rnd = new Random()

IntStream.range( 0, 10000 )
         .parallel()
         .forEach { n ->
             def key = Double.valueOf( rnd.nextGaussian() + 5 ).intValue()
             frequencyMap.computeIfAbsent( key, { k -> new LongAdder() } ).increment()
         }
          
println frequencyMap

More options in @timyates original gist: https://gist.github.com/timyates/348066a6a749ad0676f7