Reload or Renew periodically?

[Emit]

Hi, I am creating a resource that has URLs loaded from a file. I would like to use the URL one time until using all URLs and after that restart to use from the beginning. Also would like to get random each time. http://prntscr.com/rdq81q Should I use reload or renew periodically and what is the difference. And how to make it grab randomly? and what is greedy algorithm? thanks a lot

[genericname1]

I still wonder this
whats the difference between reload periodically and renew