$ perl test.pl 2 perl -e'system("sleep 4; echo My work is done")'
timed out
sent kill to 0
My work is done
$?=0

$ perl test.pl 2 perl -MPOSIX -e'setpgrp(0,0); system("sleep 4; echo My work is done")'
timed out
sent kill to 1
$?=15

##</code><code>##

eval{
     local $SIG{ALRM} = sub {die "alarm\n"};
     alarm $timeout;
     $cpid = open3("<&STDIN", ">&STDOUT", ">&STDERR", '-');

     if (!$cpid) { # Child
         setpgrp(0,0);
         exec(@ARGV)
             or die "exec: $!";
     }

     waitpid($cpid, 0);
     alarm 0;
};

##</code><code>##

$ perl fixed.pl 2 perl -e'system("sleep 4; echo My work is done")'
timed out
sent kill to 1
$?=15