Do you need to do these things asynchronously, or do you have a main loop somewhere dispatching things ?

Time::HiRes provides a higher resolution time() and sleep(). I also discovered that Time::HiRes::alarm() doesn't work, but Time::HiRes::ualarm() does -- at least on by Linux machine. Neither alarm nor ualarm work on Winders :-(

I would be nervous about doing a lot of work in a signal handler -- the documentation does not inspire confidence. However, the code below appears to work. I've included a mechanism for temporarily disabling the signal handler, which can be wrapped round any code found to be critical.

If your program can be converted into a select loop, then something like:

  while (1) {
    my $timeout = 5 ;
    while (@events) {
      $timeout = $events[-1]->[0] - Time::HiRes::time() ;
      last if ($timeout > 0.001) ;

      my ($time, $rsub, @args) = @{pop @events} ;
      $rsub->(@args) ;
      $timeout = 5 ;
    } ;

    # use IO::Select recommended, but this is just for illustration...
      
    select(my $rout = $rin, my $wout = $win, my $eout = $ein, $timeout
+) ;

    # .....
  } ;

  # add_event($delay, $rsub, @args)
  #
  #   schedule call of $rsub->(@args) in $delay (float) seconds in the
+ future

  sub add_event {
    my ($delay, $rsub, @args) = @_ ;

    my $when = $delay + Time::HiRes::time() ;

    push @events, [$when, $rsub, @args] ;

    if ((@events > 1) && ($events[-2]->[0] < $when)) {
      @events = sort { $b->[0] <=> $a->[0] } @events ;
    } ;
  } ;
[download]

Alternatively, you could poll an event loop on a regular basis. So scattering calls to something like:

  sub events {
    while (@events) {
      my $timeout = $events[-1]->[0] - Time::HiRes::time() ;
      return $timeout if ($timeout > 0.001) ;

      my ($time, $rsub, @args) = @{pop @events} ;
      $rsub->(@args) ;
    } ;
    return 5 ;
  } ;
[download]