{ ## Parent
  our ( %hash, @array, $scalar, $LOCK );     ## Global data
  my $lockfile = "./GobalLock";
  open ( $LOCK, ">>", $lockfile ) or die "Can't open $lockfile; $!\n";

  ...   # code to fork and maintain number of children
}

##</code><code>##

{
  my $need;
  ...
  if ( flock( $LOCK, LOCK_SH ) )         ## Get a copy of Global data
  {   $need = $hash{"stuff"};
      flock( $LOCK, LOCK_UN );
  }
  else { die "$!\n"; }
  ...
  if ( flock( $LOCK, LOCK_EX ) )         ## Update the Global data
  {   $hash{"stuff"} = $need;
      flock( $LOCK, LOCK_UN );
  }
  else { die "$!\n"; }
  ...
}