use strict;
use warnings;

use Time::HiRes qw( usleep time );
use threads;

{
   my $i = 0;

   my $s = time;

   my $t1 = async { usleep(250000);             };
   my $t2 = async { ++$i while $i < 50_000_000; };
   $_->join() for $t1, $t2;

   my $e = time;
   printf("%.0f\n", ($e-$s)*100000);
}

{
   my $i = 0;

   my $s = time;

   my $t1 = async {                             };
   my $t2 = async { ++$i while $i < 50_000_000; };
   $_->join() for $t1, $t2;

   my $e = time;
   printf("%.0f\n", ($e-$s)*100000);
}