Try this one

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11111868
use warnings;
use Time::HiRes qw( time sleep );

my $fudgefactor = 0.001;
while(1)
  {
  my $time = time;
  my $nextsecond = int $time + 1;
  my $interval =  $nextsecond - $time - $fudgefactor;
  $interval > 0 and sleep $interval;
  1 while time < $nextsecond;
  printf "%.6f\n", time;
  }
[download]