limit frequent http GET

If you are only concerned about limiting the number of requests on the current connection, you can do something like this:

  
 when HTTP_REQUEST { 
    set cur_time [clock seconds] 
    if { [HTTP::request_num] > 1 } { 
       if { $cur_time == $start_time } { 
          if { $reqs_sec > 3 } { 
             HTTP::respond 503 Retry-After 2 
          } 
          incr reqs_sec 
          return 
       } 
    } 
    set start_time $cur_time 
    set reqs_sec 0 
 } 
 

After 3 requests per sec, this will respond with a 503 Server unavailable and Retry-After of 2 seconds.