public static <K, V, R extends MutableMultimap<K, V>> MutableMultimap<K, V> groupBy(
            Iterable<V> iterable,
            Function<? super V, ? extends K> function,
            R concurrentMultimap,
            int batchSize)
    {
        return ParallelIterate.groupBy(iterable, function, concurrentMultimap, batchSize, ParallelIterate.EXECUTOR_SERVICE);
    }
public static < K , V , R extends MutableMultimap < K , V > > MutableMultimap < K , V > groupBy ( Iterable < V > iterable , Function < ? super V , ? extends K > function , R concurrentMultimap , int batchSize ) { return ParallelIterate . groupBy ( iterable , function , concurrentMultimap , batchSize , ParallelIterate . EXECUTOR_SERVICE ) ; }
Same effect as {@link Iterate#groupBy(Iterable, Function)},
but executed in parallel batches, and writing output into a SynchronizedPutFastListMultimap.