use threads::shared;
my $die : shared; #declare as shared before setting value
$die = 0;
 
while (<$out>) {
   return if $die;
   chomp;
   $err = 1 if (/^thread failed/);
   $Q->enqueue("$tid:$uut:$test:$_");
   last if ($err);
  }

while (1) {
  .......
  ........
 # put $die at an appropriate spot
$die =1;

......
}