use IO::Handle;

# do stuff

my $input_thread = threads->new( \&getInput );      # start the thread, wait for input

# do stuff if you feel like it

my $input = $input_thread->join || 'default input'; # wait for thread to return

sub getInput {
    my $h = IO::Handle->new_from_fd( *STDIN, r );
    $h->blocking( 0 );    # don't wait for input to return from read()s

    my $time  = time(); 
    my $input = '';

    while( 1 ){
        $h->read( $input, 20, 0 );  # read 20 chars of info if it's available
        chomp $input;  
        last if $input;             # return if we got input
        last if time() - $time > 5; # return if 5 seconds have passed
    }
}