@Override
        public int nextCapacity(int currentCapacity) {
            assert (currentCapacity > 0);
            // Guard against overflow
            return (currentCapacity * 2 > 0) ? (currentCapacity * 2) : Integer.MAX_VALUE;
        }
DOUBLE the size of the hash map every time.
indexr-query-opt/src/main/java/org/apache/spark/unsafe/map/HashMapGrowthStrategy.java