title: Saving an excel using openpyxl
body: <p>I am trying to parse a file and then save the processed data into excel using openpyxl. When the file to be parsed is small i am able to save successfully. But when the file to be parsed is big i get following error:</p>
  
  <pre><code>Traceback (most recent call last):
        File "C:\Users\522094\Desktop\vdbench\vdbench_new - Copy.py", line 195, in &lt;module&gt;
          a.generate_report()
        File "C:\Users\522094\Desktop\vdbench\vdbench_new - Copy.py", line 185, in generate_report
          self.wb.save(filename=report_path)
        File "C:\Python27\lib\site-packages\openpyxl\workbook\workbook.py", line 339, in save
          save_workbook(self, filename)
        File "C:\Python27\lib\site-packages\openpyxl\writer\excel.py", line 268, in save_workbook
          writer.save(filename)
        File "C:\Python27\lib\site-packages\openpyxl\writer\excel.py", line 250, in save
          self.write_data()
        File "C:\Python27\lib\site-packages\openpyxl\writer\excel.py", line 81, in write_data
          self._write_worksheets()
        File "C:\Python27\lib\site-packages\openpyxl\writer\excel.py", line 199, in _write_worksheets
          xml = ws._write()
        File "C:\Python27\lib\site-packages\openpyxl\worksheet\worksheet.py", line 866, in _write
          return write_worksheet(self)
        File "C:\Python27\lib\site-packages\openpyxl\writer\worksheet.py", line 177, in write_worksheet
          xf.write(tables.to_tree())
        File "C:\Python27\lib\contextlib.py", line 24, in __exit__
          self.gen.next()
        File "C:\Python27\lib\site-packages\et_xmlfile\xmlfile.py", line 50, in element
          self._write_element(el)
        File "C:\Python27\lib\site-packages\et_xmlfile\xmlfile.py", line 77, in _write_element
          xml = tostring(element)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 1126, in tostring
          ElementTree(element).write(file, encoding, method=method)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 820, in write
          serialize(write, self._root, encoding, qnames, namespaces)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 939, in _serialize_xml
          _serialize_xml(write, e, encoding, qnames, None)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 939, in _serialize_xml
          _serialize_xml(write, e, encoding, qnames, None)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 939, in _serialize_xml
          _serialize_xml(write, e, encoding, qnames, None)
        File "C:\Python27\lib\xml\etree\ElementTree.py", line 940, in _serialize_xml
          write("&lt;/" + tag + "&gt;")
      MemoryError
  </code></pre>
  
  <p>Please suggest how to resolve.</p>