my ($quit, $next_print, $next_foo) = (0, 0, 0);
while (!$quit) {
   <<<do stuff>>>
   my $cur_time = time;
   if (time > $next_print) {
      print "...\n";
      $next_print = time+5;  # wait 5s for next print
   }
   if (time > $next_foo) {
      foo(...);
      $next_foo = time+7;    # wait 7s for next foo()
   }
   <<<do more stuff>>>
}

##</code><code>##

my ($quit, $next_req, $cur_time, $cnt) = (0,0,0,0);
while (!$quit) {
   <<<do stuff>>>
   if ($cur_time<time) {
      # A new second has arrived, permit 3 more requests
      $cnt=3;
      $cur_time=time;
   }
   if ($cnt) {
      --$cnt;
      request(...);
   }
   <<<do more stuff>>>
}