Created attachment 21652 [details] Patch that fixes the bug and adds XSSF style related stuff cleanColumns() of xssf.helpers.ColumnHelper seems to have a slight bug in it. If you pass in a column definition for a long range, it'll take several minutes to run! Try running the test org.apache.poi.xssf.extractor.TestXSSFExcelExtractor One of the files that uses has a column definition for something like columns 14 to 16384 in it. cleanColumns() will still be trying to process it after about 5 minutes!
Thanks for this Paolo, committed to svn