#!/home/philou/install/perl-5.8.2-threads/bin/perl -w

use strict;
use threads;
use threads::shared;
use Thread::Semaphore;

my $s : shared = 'Thread::Semaphore'->new( 1 );

sub t {
  while( $s->down() ) {
    print "DOWN!\n";  
    sleep( 1 );
  }
}

'threads'->new( \&t );

while( <> ) {
  $s->up();
  print "UP!\n";
}