private void initialize( final int initial_sz ) {
    RangeUtil.checkPositiveOrZero(initial_sz, "initial_sz");
    int i;                      // Convert to next largest power-of-2
    for( i=MIN_SIZE_LOG; (1<<i) < initial_sz; i++ ) {/*empty*/}
    _chm = new CHM(this,new ConcurrentAutoTable(),i);
    _val_1 = TOMBSTONE;         // Always as-if deleted
    _last_resize_milli = System.currentTimeMillis();
  }
Create a new NonBlockingHashMapLong, setting both the initial size and
 the space-for-speed tradeoff.  {@code true} optimizes for space and is
 the default.  {@code false} optimizes for speed and doubles space costs
 for roughly a 10% speed improvement.
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMapLong.java