title: how to process big text file in asp.net
body: <p>My application allows user to upload CSV file that is processed and records are written in the  database. But this file can contain a very big number of records for example 300 000. And in this case it may need to up to half an hour to process all this records, I would like my application not to freeze the page for this period, but show progress and maybe some errors, or it would be better to allow user to move to another pages and from time to time come back to check process. 
  By what means can I achieve that?</p>