void function ( ) { }
this method is called after the mapping phase on the local node is over . no further combining runs will take place after this call . you override this method to clean up the internal state and free possibly acquired external resources . concode_field_sep PlaceHolder placeHolder concode_field_sep void beginCombine concode_elem_sep ValueOut finalizeChunk concode_elem_sep void reset concode_elem_sep void combine