code: @Override public void setupLocal( ) {
      // Init all the internal tree fields after shipping over the wire
      _tree.init_tree();
      // Allocate local shared memory histograms
      for( int l=_leaf; l<_tree._len; l++ ) {
        DTree.UndecidedNode udn = _tree.undecided(l);
        DHistogram hs[] = _hcs[l-_leaf];
        int sCols[] = udn._scoreCols;
        if( sCols != null ) { // Sub-selecting just some columns?
          for( int col : sCols ) // For tracked cols
            hs[col].init();
        } else {                 // Else all columns
          for( int j=0; j<_ncols; j++) // For all columns
            if( hs[j] != null )        // Tracking this column?
              hs[j].init();
        }
      }
    }
docs: Once-per-node shared init