code: public void startRehash(int newsize)
                      throws IOException,
                      EOFException,
                      FileManagerException,
                      ClassNotFoundException,
                      HashtableOnDiskException {
          if (header.rehashInProgress == 0) {
              doRehash(newsize); // time to grow the table
          }
      }
docs: ************************************************************************
  startRehash - API to force rehash. See rehash() method for details.
  Note: this could take quite a while for a large hashtable. It is
  synchronized with get, put, and remove operations, so the hashtable
  is not locked out during resize.
  
  @param newsize - the new size of the hashtable.
  ***********************************************************************