Import CSV in batches of lines in Rails?

I'm using FasterCSV to import an uploaded file to a model, and it's working great for small files. However when I try to import a large dataset (21,000 lines) it takes ages and I get browser timeouts on the live server.

This is my current working code:

  logcount=0
  Attendee.transaction do
    FCSV.new(file, :headers => true).each do |row|
      row[1] = Date.strptime(row[1], '%m/%d/%Y')
      record = @event.attendees.new(:union_id => row[0], :dob => row[1], :gender => row[2])
      if record.save
        logcount += 1
      end
    end
  end

I'd love to use a background process, but the user needs to see how many lines were imported before they can move to the next step of the system.

So, I was thinking that I should use action chunking and only read a smaller number of lines, set a counter, then update the view with some kind of progress, then run the method again using the previous counter as start point.

I can't seem to see how to get FasterCSV to read only a set number of lines, and also set an offset for the start point.

Does anyone know how to do this? Or is there a better way to handle this?

Try AR Import

Old answer

Have you tried to use AR Extensions for bulk import? You get impressive performance improvements when you are inserting 1000's of rows to DB. Visit their website for more details.