only 100 users can access my website at a time after processing 100 request i need to access another 100 requests (users) and so on how can we do it?

Hai,
  
    Q::- only 100 users can access my website at a time after processing 100 request i need to access another 100 requests (users) and so on how can we do it?

Plz send appropriate apporach for this

Thanks