use strict;
use warnings;
use threads;
use Thread::Semaphore;

my $gag = new Thread::Semaphore(0);
async   {
            $gag->down;
            while (<>) {
                print;
            }
        }->detach;
#close STDIN; # Comment this line for race-condition behavior
$gag->up;
my $value = async   {   return 1;   }->join;